Spironolactone, sold under the brand name Aldactone among others, is a medication that is primarily used to treat fluid build-up due to

heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, a ...

, liver scarring, or

kidney disease Kidney disease, or renal disease, technically referred to as nephropathy, is damage to or disease of a kidney. Nephritis is an inflammatory kidney disease and has several types according to the location of the inflammation. Inflammation can ...

. It is also used in the treatment of

high blood pressure Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

, low blood potassium that does not improve with supplementation, early puberty in boys, acne and excessive hair growth in women, and as a part of transgender hormone therapy in transfeminine people. Spironolactone is taken by mouth. Common side effects include electrolyte abnormalities, particularly high blood potassium, nausea, vomiting, headache, rashes, and a decreased desire for sex. In those with liver or kidney problems, extra care should be taken. Spironolactone has not been well studied in pregnancy and should not be used to treat high blood pressure of pregnancy. It is a

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

that blocks the effects of the hormones

aldosterone Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays a c ...

and testosterone and has some estrogen-like effects. Spironolactone belongs to a class of medications known as potassium-sparing diuretics. Spironolactone was discovered in 1957, and was introduced in 1959. It is on the World Health Organization's List of Essential Medicines. It is available as a

generic medication A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active ch ...

. In 2020, it was the 51st most commonly prescribed medication in the United States, with more than 13million prescriptions.

Medical uses

Spironolactone is used primarily to treat

edema Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's Tissue (biology), tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels t ...

tous conditions such as

nephrotic syndrome Nephrotic syndrome is a collection of symptoms due to kidney damage. This includes protein in the urine, low blood albumin levels, high blood lipids, and significant swelling. Other symptoms may include weight gain, feeling tired, and foamy ...

or ascites in people with liver disease, essential

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

, low blood levels of potassium,

secondary hyperaldosteronism Hyperaldosteronism is a medical condition wherein too much aldosterone is produced by the adrenal glands, which can lead to lowered levels of potassium in the blood ( hypokalemia) and increased hydrogen ion excretion (alkalosis). This cause of m ...

(such as occurs with liver cirrhosis), and Conn's syndrome (primary hyperaldosteronism). The most common use of spironolactone is in the treatment of heart failure. On its own, spironolactone is only a weak diuretic because it primarily targets the

distal nephron The nephron is the minute or microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structure ...

(

collecting tubule The collecting duct system of the kidney consists of a series of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis. The collecting duct system is the last part of nephron and participates in elect ...

), where only small amounts of sodium are reabsorbed, but it can be combined with other diuretics to increase efficacy. The classification of spironolactone as a "potassium-sparing diuretic" has been described as obsolete. Spironolactone is also used to treat

Bartter's syndrome Bartter syndrome (BS) is a rare inherited disease characterised by a defect in the thick ascending limb of the loop of Henle, which results in low potassium levels ( hypokalemia), increased blood pH (alkalosis), and normal to low blood pressure. ...

due to its ability to raise potassium levels. Spironolactone has antiandrogenic activity. For this reason, it is frequently used to treat a variety of dermatological conditions in which androgens play a role. Some of these uses include acne, seborrhea, hirsutism, and pattern hair loss in women. Spironolactone is the most commonly used medication in the treatment of hirsutism in the United States. High doses of spironolactone, which are needed for considerable antiandrogenic effects, are not recommended for men due to the high risk of feminization and other side effects. Spironolactone can be used to treat

symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...

s of hyperandrogenism, such as due to polycystic ovary syndrome, in women, dose of 50-100mg in 1 or 2 doses.

Heart failure

While loop diuretics remain first-line for most people with

, spironolactone has shown to reduce both morbidity and mortality in numerous studies and remains an important agent for treating fluid retention, edema, and symptoms of heart failure. Current recommendations from the

American Heart Association The American Heart Association (AHA) is a nonprofit organization in the United States that funds cardiovascular medical research, educates consumers on healthy living and fosters appropriate cardiac care in an effort to reduce disability and death ...

are to use spironolactone in patients with NYHA Class II-IV heart failure who have a left ventricular ejection fraction of less than 35%. In a

randomized evaluation A randomized controlled trial (or randomized control trial; RCT) is a form of scientific experiment used to control factors not under direct experimental control. Examples of RCTs are clinical trials that compare the effects of drugs, surgical ...

which studied people with severe congestive heart failure, people treated with spironolactone were found to have a

relative risk The relative risk (RR) or risk ratio is the ratio of the probability of an outcome in an exposed group to the probability of an outcome in an unexposed group. Together with risk difference and odds ratio, relative risk measures the association bet ...

of death of 0.70 or an overall 30% relative risk reduction compared to the placebo group, indicating a significant death and morbidity benefit of the medication. People in the study's intervention arm also had fewer symptoms of

and were hospitalized less frequently. Likewise, it has shown benefit for and is recommended in patients who recently had a heart attack and have an ejection fraction less than 40%, who develop symptoms consistent with heart failure, or have a history of diabetes mellitus. Spironolactone should be considered a good add-on agent, particularly in those patients "not" yet optimized on ACE inhibitors and

beta-blockers Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms, and to protect the heart from a second heart attack after a first heart attack (secondary prevention). They are al ...

. Of note, a recent randomized, double-blinded study of spironolactone in patients with symptomatic heart failure with "preserved" ejection fraction (i.e. >45%) found no reduction in death from cardiovascular events, aborted cardiac arrest, or hospitalizations when spironolactone was compared to placebo. It is recommended that alternatives to spironolactone be considered if serum creatinine is greater than 2.5 mg/dL (221 μmol/L) in males or greater than 2 mg/dL (176.8 μmol/L) in females, if glomerular filtration rate is below 30 mL/min or with a serum potassium of greater than 5.0 mEq/L given the potential for adverse events detailed elsewhere in this article. Doses should be adjusted according to the degree of kidney function as well. According to a

systematic review A systematic review is a Literature review, scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic. A systematic review extracts and interprets data from publ ...

, in

with preserved ejection fraction, treatment with spironolactone did not improve patient outcomes. This is based on the TOPCAT Trial examining this issue, which found that of those treated with placebo had a 20.4% incidence of negative outcome vs 18.6% incidence of negative outcome with spironolactone. However, because the

p-value In null-hypothesis significance testing, the ''p''-value is the probability of obtaining test results at least as extreme as the result actually observed, under the assumption that the null hypothesis is correct. A very small ''p''-value means ...

of the study was 0.14, and the unadjusted hazard ratio was 0.89 with a 95%

confidence interval In frequentist statistics, a confidence interval (CI) is a range of estimates for an unknown parameter. A confidence interval is computed at a designated ''confidence level''; the 95% confidence level is most common, but other levels, such as 9 ...

of 0.77 to 1.04, it is determined the finding had no

statistical significance In statistical hypothesis testing, a result has statistical significance when it is very unlikely to have occurred given the null hypothesis (simply by chance alone). More precisely, a study's defined significance level, denoted by \alpha, is the p ...

. Hence the finding that patient outcomes are not improved with use of spironolactone. When blood samples from 366 participants in the TOPCAT study were analyzed for presence of

canrenone Canrenone, sold under the brand names Contaren, Luvion, Phanurane, and Spiroletan, is a steroidal antimineralocorticoid of the spirolactone group related to spironolactone which is used as a diuretic in Europe, including in Italy and Belgium. It ...

(an active metabolite of spironolactone), 30% of blood samples from Russia lacked detectable residues of canrenone. This led to the conclusion that the TOPCAT trial results in Russia do not reflect actual clinical experience with spironolactone in patients with preserved ejection fraction. The TOPCAT study results are now considered to have been invalidated. The study's prime investigator and other prominent research cardiologists are now advising physicians treating heart failure with preserved ejection fraction to consider prescribing spironolactone pending outcome of two multicenter trials of newer medications. Due to its antiandrogenic properties, spironolactone can cause effects associated with low androgen levels and hypogonadism in males. For this reason, men are typically not prescribed spironolactone for any longer than a short period of time, e.g., for an acute exacerbation of heart failure. A newer medication, eplerenone, has been approved by the U.S. Food and Drug Administration for the treatment of heart failure, and lacks the antiandrogenic effects of spironolactone. As such, it is far more suitable for men for whom long-term medication is being chosen. However, eplerenone may not be as effective as spironolactone or the related medication

in reducing mortality from heart failure. The clinical benefits of spironolactone as a diuretic are typically not seen until 2–3 days after dosing begins. Likewise, the maximal antihypertensive effect may not be seen for 2–3 weeks. Unlike with some other diuretics, potassium supplementation should ''not'' be administered while taking spironolactone, as this may cause dangerous elevations in serum potassium levels resulting in hyperkalemia and potentially deadly abnormal heart rhythms.

High blood pressure

About 1 in 100 people with hypertension have elevated levels of aldosterone; in these people, the antihypertensive effect of spironolactone may exceed that of complex combined regimens of other antihypertensives since it targets the primary cause of the elevated blood pressure. However, a Cochrane review found adverse effects at high doses and little effect on blood pressure at low doses in the majority of people with high blood pressure. There is no evidence of person-oriented outcome at any dose in this group.

High aldosterone levels

Spironolactone is used in the treatment of

hyperaldosteronism Hyperaldosteronism is a medical condition wherein too much aldosterone is produced by the adrenal glands, which can lead to lowered levels of potassium in the blood (hypokalemia) and increased hydrogen ion excretion (alkalosis). This cause of min ...

(high aldosterone levels or mineralocorticoid excess), for instance primary aldosteronism (Conn's syndrome). Antimineralocorticoids like spironolactone and eplerenone are first-line treatments for hyperaldosteronism. They improve blood pressure and potassium levels, as well as left ventricular hypertrophy, albuminuria, and

carotid intima-media thickness In anatomy, the left and right common carotid arteries (carotids) (Entry "carotid"
in
In people with hyperaldosteronism due to unilateral aldosterone-producing

adrenocortical adenoma Adrenocortical adenoma is commonly described as a benign neoplasm emerging from the cells that comprise the adrenal cortex. Like most adenomas, the adrenocortical adenoma is considered a benign tumor since the majority of them are non-functioning ...

, adrenalectomy should be preferred instead of antimineralocorticoids. Spironolactone should not be used to treat primary aldosteronism in pregnancy due to its antiandrogen-related risk of teratogenicity in male fetuses.

Skin and hair conditions

Androgens like testosterone and DHT play a critical role in the pathogenesis of a number of dermatological conditions including oily skin, acne, seborrhea, hirsutism (excessive facial/body hair growth in women), and

male pattern hair loss Pattern hair loss (also known as androgenetic alopecia (AGA)) is a hair loss condition that primarily affects the top and front of the scalp. In male-pattern hair loss (MPHL), the hair loss typically presents itself as either a receding front ha ...

(androgenic alopecia). In demonstration of this, women with complete androgen insensitivity syndrome (CAIS) do not produce sebum or develop acne and have little to no body, pubic, or axillary hair. Moreover, men with

congenital A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...

5α-reductase type II deficiency,

5α-reductase 5α-Reductases, also known as 3-oxo-5α-steroid 4-dehydrogenases, are enzymes involved in steroid metabolism. They participate in three metabolic pathways: bile acid biosynthesis, androgen and estrogen metabolism. There are three isozymes of ...

being an enzyme that greatly potentiates the androgenic effects of testosterone in the skin, have little to no acne, scanty

facial hair Facial hair is hair grown on the face, usually on the chin, cheeks, and upper lip region. It is typically a secondary sex characteristic of human males. Men typically start developing facial hair in the later stages of puberty or adolescence, ...

, reduced body hair, and reportedly no incidence of male-pattern hair loss. Conversely, hyperandrogenism in women, for instance due to polycystic ovary syndrome (PCOS) or congenital adrenal hyperplasia (CAH), is commonly associated with acne and hirsutism as well as virilization (masculinization) in general. In accordance with the preceding, antiandrogens are highly effective in the treatment of the aforementioned androgen-dependent skin and hair conditions. Because of the antiandrogenic activity of spironolactone, it can be quite effective in treating acne in women. In addition, spironolactone reduces oil that is naturally produced in the skin and can be used to treat oily skin. Though not the primary intended purpose of the medication, the ability of spironolactone to be helpful with problematic skin and acne conditions was discovered to be one of the beneficial side effects and has been quite successful. Oftentimes, for women treating acne, spironolactone is prescribed and paired with a birth control pill. Positive results in the pairing of these two medications have been observed, although these results may not be seen for up to three months. Spironolactone has been reported to produce a 50 to 100% improvement in acne at sufficiently high doses. Response to treatment generally requires 1 to 3 months in the case of acne and up to 6 months in the case of hirsutism. Ongoing therapy is generally required to avoid relapse of symptoms. Spironolactone is commonly used in the treatment of hirsutism in women, and is considered to be a first-line antiandrogen for this indication. Spironolactone can be used in the treatment of female-pattern hair loss (pattern scalp hair loss in women). There is tentative low quality evidence supporting its use for this indication. Although apparently effective, not all cases of female-pattern hair loss are dependent on androgens. Antiandrogens like spironolactone are male-specific teratogens which can feminize male fetuses due to their antiandrogenic effects. For this reason, it is recommended that antiandrogens only be used to treat women who are of reproductive age in conjunction with adequate contraception. Oral contraceptives, which contain an estrogen and a

progestin A progestogen, also referred to as a progestagen, gestagen, or gestogen, is a type of medication which produces effects similar to those of the natural product, natural female sex hormone progesterone in the body. A progestin is a ''synthetic co ...

, are typically used for this purpose. Moreover, oral contraceptives themselves are functional antiandrogens and are independently effective in the treatment of androgen-dependent skin and hair conditions, and hence can significantly augment the effectiveness of antiandrogens in the treatment of such conditions. Spironolactone is not generally used in men for the treatment of androgen-dependent dermatological conditions because of its feminizing side effects, but it is effective for such indications in men similarly. As an example, spironolactone has been reported to reduce symptoms of acne in males. An additional example is the usefulness of spironolactone as an antiandrogen in transgender women. Topical spironolactone has been found to be effective in the treatment of acne as well. As a result, topical pharmaceutical formulations containing 2% or 5% spironolactone cream became available in Italy for the treatment of acne and hirsutism in the early 1990s. The products were discontinued in 2006 when the creams were added to the list of doping substances with a decree of the

Ministry of Health Ministry of Health may refer to: Note: Italics indicate now-defunct ministries. * Ministry of Health (Argentina) * Ministry of Health (Armenia) * Australia: ** Ministry of Health (New South Wales) * Ministry of Health (The Bahamas) * Ministry of ...

that year.

Comparison

Spironolactone, the

5α-reductase inhibitor 5α-Reductases, also known as 3-oxo-5α-steroid 4-dehydrogenases, are enzymes involved in steroid metabolism. They participate in three metabolic pathways: bile acid biosynthesis, androgen and estrogen metabolism. There are three isozymes of ...

finasteride Finasteride, sold under the brand names Proscar and Propecia among others, is a medication used to treat hair loss and benign prostatic hyperplasia (BPH) in men. It can also be used to treat excessive hair growth in women and as a part of horm ...

, and the nonsteroidal antiandrogen flutamide all appear to have similar effectiveness in the treatment of hirsutism. However, some clinical research has found that the effectiveness of spironolactone for hirsutism is greater than that of finasteride but is less than that of flutamide. The combination of spironolactone with finasteride is more effective than either alone for hirsutism and the combination of spironolactone with a birth control pill is more effective than a birth control pill alone. One study showed that spironolactone or the

steroidal antiandrogen A steroidal antiandrogen (SAA) is an antiandrogen with a steroidal chemical structure. They are typically antagonists of the androgen receptor (AR) and act both by blocking the effects of androgens like testosterone and dihydrotestosterone (DHT) ...

cyproterone acetate both in combination with a birth control pill had equivalent effectiveness for hirsutism. Spironolactone is considered to be a first-line treatment for hirsutism, finasteride and the steroidal antiandrogen cyproterone acetate are considered to be second-line treatments, and flutamide is no longer recommended for hirsutism due to

liver toxicity Hepatotoxicity (from ''hepatic toxicity'') implies chemical-driven liver damage. Drug-induced liver injury is a cause of acute and chronic liver disease caused specifically by medications and the most common reason for a drug to be withdrawn fro ...

concerns. The nonsteroidal antiandrogen bicalutamide is an alternative option to flutamide with improved safety. The combination of spironolactone with a birth control pill in the treatment of acne appears to have similar effectiveness to a birth control pill alone and the combination of a birth control pill with cyproterone acetate, flutamide, or finasteride. However, this was based on low- to very-low-quality evidence. Spironolactone may be more effective than birth control pills in the treatment of acne, and the combination of spironolactone with a birth control pill may have greater effectiveness for acne than either alone. In addition, some clinical research has found that flutamide is more effective than spironolactone in the treatment of acne. In one study, flutamide decreased acne scores by 80% within 3 months, whereas spironolactone decreased symptoms by only 40% in the same time period. However, the use of flutamide for acne is limited by its liver toxicity. Bicalutamide is a potential alternative to flutamide for acne as well. Spironolactone can be considered as a first-line treatment for acne in those who have failed other standard treatments such as topical therapies and under certain other circumstances, although this is controversial due to the side effects of spironolactone and its teratogenicity. There is insufficient clinical evidence to compare the effectiveness of spironolactone with other antiandrogens for female-pattern hair loss. The effectiveness of spironolactone in the treatment of both acne and hirsutism appears to be dose-dependent, with higher doses being more effective than lower doses. However, higher doses also have greater side effects, such as menstrual irregularities.

Alternative Spironolactone Use

Spironolactone medication is not approved for use as an antiandrogen by the Food and Drug Administration; instead, it is used off-label for such purposes.

Doses and forms

Spironolactone is typically used at a low dosage of 25 to 50 mg/day in the treatment of heart failure, while it is used at low to high dosages of 25 to 200 mg/day in the treatment of essential hypertension, and at high dosages of 100 to 400 mg/day for

and ascites due to cirrhosis. The medication is typically used at high dosages of 100 to 200 mg/day in the treatment of skin and hair conditions in women, and at high dosages of 100 to 400 mg/day in feminizing hormone therapy for transgender women. Spironolactone can be used to treat

s of hyperandrogenism, such as polycystic ovary syndrome, in women, dose of 50-100mg in 1 or 2 doses. Spironolactone is available in the form of

tablet Tablet may refer to: Medicine * Tablet (pharmacy), a mixture of pharmacological substances pressed into a small cake or bar, colloquially called a "pill" Computing * Tablet computer, a mobile computer that is primarily operated by touching the s ...

s (25 mg, 50 mg, 100 mg; brand name Aldactone, others) and suspensions (25 mg/5 mL; brand name CaroSpir) for use by mouth. It has also been marketed in the form of 2% and 5% topical cream in Italy for the treatment of acne and hirsutism under the brand name Spiroderm, but this product is no longer available. The medication is also available in combination with other medications, such as hydrochlorothiazide (brand name Aldactazide, others). Spironolactone has poor water solubility, and for this reason, only oral and topical formulations have been developed; other routes of administration such as

intravenous injection Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutri ...

are not used. The only antimineralocorticoid that is available as a solution for parenteral use is the related medication

potassium canrenoate Potassium canrenoate (INN, JAN) or canrenoate potassium (USAN) (brand names Venactone, Soldactone), also known as aldadiene kalium, the potassium salt of canrenoic acid, is an aldosterone antagonist of the spirolactone group. Like spironolactone, ...

Contraindications

Contraindications of spironolactone include hyperkalemia (high potassium levels), severe and end-stage kidney disease (due to high hyperkalemia risk, except possibly in those on

dialysis Dialysis may refer to: *Dialysis (chemistry), a process of separating molecules in solution **Electrodialysis, used to transport salt ions from one solution to another through an ion-exchange membrane under the influence of an applied electric pote ...

), Addison's disease (adrenal insufficiency and low aldosterone levels), and concomitant use of eplerenone. It should also be used with caution in people with some neurological disorders, no urine production, acute kidney injury, or significant impairment of kidney excretory function with risk of hyperkalemia.

Side effects

One of the most common side effects of spironolactone is frequent urination. Other general side effects include dehydration, hyponatremia (low sodium levels), mild hypotension (low

blood pressure Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" r ...

), ataxia (muscle incoordination), drowsiness, dizziness, dry skin, and rashes. Because of its antiandrogenic activity, spironolactone can, in men, cause breast tenderness, gynecomastia (breast development), feminization in general, and demasculinization, as well as sexual dysfunction including loss of libido and

erectile dysfunction Erectile dysfunction (ED), also called impotence, is the type of sexual dysfunction in which the penis fails to become or stay erect during sexual activity. It is the most common sexual problem in men.Cunningham GR, Rosen RC. Overview of male ...

, although these side effects are usually confined to high doses of spironolactone. At very high doses (400 mg/day), spironolactone has also been associated with testicular atrophy and reversibly reduced fertility, including

semen abnormalities A semen analysis (plural: semen analyses), also called seminogram or spermiogram, evaluates certain characteristics of a male's semen and the sperm contained therein. It is done to help evaluate male fertility, whether for those seeking pregnancy ...

such as decreased sperm count and motility in men. However, such doses of spironolactone are rarely used clinically. In women, spironolactone can cause menstrual irregularities, breast tenderness, and breast enlargement. Aside from these adverse effects, the side effects of spironolactone in women taking high doses are minimal, and it is well tolerated. The most important potential side effect of spironolactone is hyperkalemia (high potassium levels), which, in severe cases, can be life-threatening. Hyperkalemia in these people can present as a normal anion-gap metabolic acidosis. It has been reported that the addition of spironolactone to loop diuretics in patients with heart failure was associated with a higher risk of hyperkalemia and acute kidney injury (AKI). Spironolactone may put people at a heightened risk for gastrointestinal issues like nausea, vomiting, diarrhea, cramping, and gastritis. In addition, there has been some evidence suggesting an association between use of the medication and bleeding from the stomach and

duodenum The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear, and the terms anterior intestine or proximal intestine m ...

, though a causal relationship between the two has not been established. Also, spironolactone is immunosuppressive in the treatment of sarcoidosis. Most of the side effects of spironolactone are dose-dependent. Low-dose spironolactone is generally very well tolerated. Even higher doses of spironolactone, such as 100 mg/day, are well tolerated in most individuals. Dose-dependent side effects of spironolactone include menstrual irregularities, breast tenderness and enlargement, orthostatic hypotension, and hyperkalemia. The side effects of spironolactone are usually mild and rarely result in discontinuation.

High potassium levels

Spironolactone can cause hyperkalemia, or high blood potassium levels. Rarely, this can be fatal. Of people with heart disease prescribed typical dosages of spironolactone, 10 to 15% develop some degree of hyperkalemia, and 6% develop severe hyperkalemia. At a higher dosage, a rate of hyperkalemia of 24% has been observed. An abrupt and major increase in the rate of hospitalization due to hyperkalemia from 0.2% to 11% and in the rate of death due to hyperkalemia from 0.3 per 1,000 to 2.0 per 1,000 between early 1994 and late 2001 has been attributed to a parallel rise in the number of prescriptions written for spironolactone upon the publication of the Randomized Aldactone Evaluation Study (RALES) in July 1999. However, another population-based study in Scotland failed to replicate these findings. The risk of hyperkalemia with spironolactone is greatest in the elderly, in people with renal impairment (e.g., due to

chronic kidney disease Chronic kidney disease (CKD) is a type of kidney disease in which a gradual loss of kidney function occurs over a period of months to years. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, vo ...

or diabetic nephropathy), in people taking certain other medications (including inhibitors, angiotensin II receptor blockers,

nonsteroidal anti-inflammatory drug Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...

s, the

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...

trimethoprim, and potassium

supplement Supplement or Supplemental may refer to: Health and medicine * Bodybuilding supplement * Dietary supplement * Herbal supplement Media * Supplement (publishing), a publication that has a role secondary to that of another preceding or concurre ...

s), and at higher dosages of spironolactone. Although spironolactone poses an important risk of hyperkalemia in the elderly, in those with kidney or cardiovascular disease, and/or in those taking medications or supplements which increase circulating potassium levels, a large retrospective study found that the rate of hyperkalemia in young women without such characteristics who had been treated with high doses of spironolactone for dermatological conditions did not differ from that of controls. This was the conclusion of a 2017 hybrid systematic review of studies of spironolactone for acne in women as well, which found that hyperkalemia was rare and was invariably mild and clinically insignificant. These findings suggest that hyperkalemia may not be a significant risk in such individuals, and that routine monitoring of circulating potassium levels may be unnecessary in this population. However, other sources have claimed that hyperkalemia can nonetheless also occur in people with more normal renal function and presumably without such risk factors. Occasional testing on a case-by-case basis in those with known risk factors may be justified. Side effects of spironolactone which may be indicative of hyperkalemia and if persistent could justify serum potassium testing include nausea, fatigue, and particularly muscle weakness. Notably, non-use of routine potassium monitoring with spironolactone in young women would reduce costs associated with its use.

Breast changes

Spironolactone frequently causes

breast pain Breast pain is the symptom of discomfort in either one or both breasts. Pain in both breasts is often described as ''breast tenderness'', is usually associated with the menstrual period and is not serious. Pain that involves only one part of a br ...

and breast enlargement in women. This is "probably because of estrogenic effects on target tissue." At low doses, breast tenderness has been reported in only 5% of women, but at high doses, it has been reported in up to 40% of women. Breast enlargement and tenderness may occur in 26% of women at high doses. Some women regard spironolactone-induced breast enlargement as a positive effect. Spironolactone also commonly and dose-dependently produces gynecomastia (breast development) as a side effect in men. At low doses, the rate is only 5 to 10%, but at high doses, up to or exceeding 50% of men may develop gynecomastia. In the RALES, 9.1% of men taking 25 mg/day spironolactone developed gynecomastia, compared to 1.3% of controls. Conversely, in studies of healthy men given high-dose spironolactone, gynecomastia occurred in 3 of 10 (30%) at 100 mg/day, in 5 of 8 (62.5%) at 200 mg/day, and in 6 of 9 (66.7%) at 400 mg/day, relative to none of 12 controls. The severity of gynecomastia with spironolactone varies considerably, but is usually mild. As with breast enlargement caused by spironolactone in women, gynecomastia due to spironolactone in men is often although inconsistently accompanied by breast tenderness. In the RALES, only 1.7% of men developed breast pain, relative to 0.1% of controls. The time to onset of spironolactone-induced gynecomastia has been found to be 27 ± 20 months at low doses and 9 ± 12 months at high doses. Gynecomastia induced by spironolactone usually regresses after a few weeks following discontinuation of the medication. However, after a sufficient duration of gynecomastia being present (e.g., one year),

hyalinization A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

and fibrosis of the tissue occurs and drug-induced gynecomastia may become irreversible.

Menstrual disturbances

Spironolactone at higher doses can cause menstrual irregularities as a side effect in women. These irregularities include metrorrhagia (intermenstrual bleeding), amenorrhea (absence of menstruation), and

breakthrough bleeding Intermenstrual bleeding, previously known as metrorrhagia, is uterine bleeding at irregular intervals, particularly between the expected menstrual periods. It is a cause of vaginal bleeding. In some women, menstrual spotting between periods occur ...

. They are common during spironolactone therapy, with 10 to 50% of women experiencing them at moderate doses and almost all experiencing them at a high doses. For example, about 20% of women experienced menstrual irregularities with 50 to 100 mg/day spironolactone, whereas about 70% experienced menstrual irregularities at 200 mg/day. Most women taking moderate doses of spironolactone develop amenorrhea, and normal

menstruation Menstruation (also known as a period, among other colloquial terms) is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. The menstrual cycle is characterized by the rise and fall of hor ...

usually returns within two months of discontinuation. Spironolactone produces an irregular and anovulatory pattern of

menstrual cycle The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that make pregnancy possible. The ovarian cycle controls the production and release of eggs a ...

s. It is also associated with metrorrhagia and

menorrhagia Heavy menstrual bleeding (HMB), previously known as menorrhagia or hypermenorrhea, is a menstrual period with excessively heavy flow. It is a type of abnormal uterine bleeding Abnormal uterine bleeding (AUB), also known as (AVB) or as atypical ...

(heavy menstrual bleeding) in large percentages of women, as well as with

polymenorrhea Polymenorrhea, also known as frequent periods, frequent menstruation, or frequent menstrual bleeding, is a menstrual disorder in which menstrual cycles are shorter than 21days in length and hence where menstruation occurs more frequently than usu ...

(short menstrual cycles). The medication reportedly has no

birth control Birth control, also known as contraception, anticonception, and fertility control, is the use of methods or devices to prevent unwanted pregnancy. Birth control has been used since ancient times, but effective and safe methods of birth contr ...

effect. It has been suggested that the weak progestogenic activity of spironolactone is responsible for these effects, although this has not been established and spironolactone has been shown to possess insignificant progestogenic and antiprogestogenic activity even at high dosages in women. An alternative proposed cause is inhibition of 17α-hydroxylase and hence

sex steroid Sex hormones, also known as sex steroids, gonadocorticoids and gonadal steroids, are steroid hormones that interact with vertebrate steroid hormone receptors. The sex hormones include the androgens, estrogens, and progestogens. Their effects are ...

metabolism by spironolactone and consequent changes in sex hormone levels. Indeed, CYP17A1

genotype The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the alleles or variants an individual carries in a particular gene or genetic location. The number of alleles an individual can have in a ...

is associated with polymenorrhea. Regardless of their mechanism, the menstrual disturbances associated with spironolactone can usually be controlled well by concomitant treatment with a birth control pill, due to the

component.

Mood changes

Research is mixed on whether antimineralocorticoids like spironolactone have positive or negative effects on mood. In any case, it is possible that spironolactone might have the capacity to increase the risk of depressive symptoms. However, a 2017 hybrid systematic review found that the incidence of depression in women treated with spironolactone for acne was less than 1%. Likewise, a 10-year observational study found that the incidence of depression in 196 transgender women taking high-dose spironolactone in combination with an estrogen was less than 1%.

Rare reactions

Aside from hyperkalemia, spironolactone may rarely cause adverse reactions such as anaphylaxis, kidney failure, hepatitis (two reported cases, neither serious),

agranulocytosis Agranulocytosis, also known as agranulosis or granulopenia, is an acute condition involving a severe and dangerous lowered white blood cell count (leukopenia, most commonly of neutrophils) and thus causing a neutropenia in the circulating blood. ...

, DRESS syndrome, Stevens–Johnson syndrome or toxic epidermal necrolysis. Five cases of breast cancer in patients who took spironolactone for prolonged periods of time have been reported.

Spironolactone bodies

Long-term administration of spironolactone gives the

histologic Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...

characteristic of "spironolactone bodies" in the

adrenal cortex The adrenal cortex is the outer region and also the largest part of an adrenal gland. It is divided into three separate zones: zona glomerulosa, zona fasciculata and zona reticularis. Each zone is responsible for producing specific hormones. It is ...

. Spironolactone bodies are eosinophilic, round, concentrically laminated cytoplasmic inclusions surrounded by clear halos in preparations stained with hematoxylin and eosin.

Pregnancy and breastfeeding

In the United States, spironolactone is considered pregnancy category C meaning that it is unclear if it is safe for use during pregnancy. It is able to cross the placenta. Likewise, it has been found to be present in the breast milk of lactating mothers and, while the effects of spironolactone or its metabolites have not been extensively studied in breastfeeding infants, it is generally recommended that women also not take the medication while nursing. However, only very small amounts of spironolactone and its metabolite canrenone enter

breast milk Breast milk (sometimes spelled as breastmilk) or mother's milk is milk produced by mammary glands located in the breast of a human female. Breast milk is the primary source of nutrition for newborns, containing fat, protein, carbohydrates ( lacto ...

, and the amount received by an infant during breastfeeding (<0.5% of the mother's dose) is considered to be insignificant. A study found that spironolactone was not associated with teratogenicity in the offspring of rats. Because it is an antiandrogen, however, spironolactone could theoretically have the potential to cause feminization of male fetuses at sufficient doses. In accordance, a subsequent study found that partial feminization of the genitalia occurred in the male offspring of rats that received doses of spironolactone that were five times higher than those normally used in humans (200 mg/kg per day). Another study found permanent, dose-related reproductive tract abnormalities rat offspring of both sexes at lower doses (50 to 100 mg/kg per day). In practice however, although experience is limited, spironolactone has never been reported to cause observable feminization or any other congenital defects in humans. Among 31 human newborns exposed to spironolactone in the first trimester, there were no signs of any specific birth defects. A case report described a woman who was prescribed spironolactone during pregnancy with triplets and delivered all three (one boy and two girls) healthy; there was no feminization in the boy. In addition, spironolactone has been used at high doses to treat pregnant women with

, and none of the infants (three boys, two girls) showed toxicity, including feminization in the male infants. There are similar findings, albeit also limited, for another antiandrogen, cyproterone acetate (prominent genital defects in male rats, but no human abnormalities (including feminization of male fetuses) at both a low dose of 2 mg/day or high doses of 50 to 100 mg/day). In any case, spironolactone is nonetheless not recommended during pregnancy due to theoretical concerns relating to feminization of males and also to potential alteration of fetal potassium levels. A 2019 systematic review found insufficient evidence that spironolactone causes birth defects in humans. However, there was also insufficient evidence to be certain that it does not.

Overdose

Spironolactone is relatively safe in acute overdose.

Symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...

s following an acute overdose of spironolactone may include drowsiness, confusion, maculopapular or erythematous rash, nausea, vomiting, dizziness, and diarrhea. In rare cases, hyponatremia, hyperkalemia, or

hepatic coma Hepatic encephalopathy (HE) is an altered level of consciousness as a result of liver failure. Its onset may be gradual or sudden. Other symptoms may include movement problems, changes in mood, or changes in personality. In the advanced stages ...

may occur in individuals with

severe liver disease Liver disease, or hepatic disease, is any of many diseases of the liver. If long-lasting it is termed chronic liver disease. Although the diseases differ in detail, liver diseases often have features in common. Signs and symptoms Some of the sig ...

. However, these

adverse reaction An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. The term complica ...

s are unlikely in the event of an acute overdose. Hyperkalemia can occur following an overdose of spironolactone, and this is especially so in people with decreased kidney function. Spironolactone has been studied at extremely high oral doses of up to 2,400 mg per day in clinical trials. Its oral

median lethal dose In toxicology, the median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a toxin, radiation, or pathogen. The value of LD50 for a substance is the ...

(LD₅₀) is more than 1,000 mg/kg in mice, rats, and rabbits. There is no specific antidote for overdose of spironolactone. Treatment may consist of induction of vomiting or stomach evacuation by gastric lavage. The treatment of spironolactone overdose is supportive, with the purpose of maintaining hydration,

electrolyte balance An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...

, and vital functions. Spironolactone should be discontinued in people with impaired kidney function or hyperkalemia.

Interactions

Spironolactone often increases serum potassium levels and can cause hyperkalemia, a very serious condition. Therefore, it is recommended that people using this medication avoid potassium supplements and salt substitutes containing potassium. Physicians must be careful to monitor potassium levels in both males and females who are taking spironolactone as a diuretic, especially during the first twelve months of use and whenever the dosage is increased. Doctors may also recommend that some patients may be advised to limit dietary consumption of potassium-rich foods. However, recent data suggests that both potassium monitoring and dietary restriction of potassium intake is unnecessary in healthy young women taking spironolactone for acne. Spironolactone together with trimethoprim/sulfamethoxazole increases the likelihood of hyperkalemia, especially in the elderly. The trimethoprim portion acts to prevent potassium excretion in the distal tubule of the nephron. Spironolactone has been reported to induce the enzymes

CYP3A4 Cytochrome P450 3A4 (abbreviated CYP3A4) () is an important enzyme in the body, mainly found in the liver and in the intestine. It oxidizes small foreign organic molecules (xenobiotics), such as toxins or drugs, so that they can be removed from t ...

and certain UDP-glucuronosyltransferases (UGTs), which can result in interactions with various medications. However, it has also been reported that metabolites of spironolactone irreversibly inhibit CYP3A4. In any case, spironolactone has been found to reduce the bioavailability of oral estradiol, which could be due to induction of estradiol metabolism via CYP3A4. Spironolactone has also been found to inhibit UGT2B7. Spironolactone can also have numerous other interactions, most commonly with other cardiac and blood pressure medications, for instance

digoxin Digoxin (better known as Digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. Digoxin is on ...

. Licorice, which has indirect mineralocorticoid activity by inhibiting mineralocorticoid metabolism, has been found to inhibit the antimineralocorticoid effects of spironolactone. Moreover, the addition of licorice to spironolactone has been found to reduce the antimineralocorticoid side effects of spironolactone in women treated with it for hyperandrogenism, and licorice hence may be used to reduce these side effects in women treated with spironolactone as an antiandrogen who are bothered by them. On the opposite end of the spectrum, spironolactone is useful in reversing licorice-induced hypokalemia. Aspirin and other

s (NSAIDs) have been found to attenuate the diuresis and natriuresis induced by spironolactone, but, not to affect its antihypertensive effect. Some research has suggested that spironolactone might be able to interfere with the effectiveness of

antidepressant Antidepressants are a class of medication used to treat major depressive disorder, anxiety disorders, chronic pain conditions, and to help manage addictions. Common side-effects of antidepressants include dry mouth, weight gain, dizziness, hea ...

treatment. As the medication acts as an antimineralocorticoid, it is thought that it might be able to reduce the effectiveness of certain antidepressants by interfering with normalization of the hypothalamic–pituitary–adrenal axis and by increasing levels of glucocorticoids such as

cortisol Cortisol is a steroid hormone, in the glucocorticoid class of hormones. When used as a medication, it is known as hydrocortisone. It is produced in many animals, mainly by the ''zona fasciculata'' of the adrenal cortex in the adrenal gland ...

.Holsboer, F. The Rationale for Corticotropin-Releasing Hormone Receptor (CRH-R) Antagonists to Treat Depression and Anxiety. J. Psychiatr. Res. 33, 181–214 (1999). However, other research contradicts this hypothesis and has suggested that spironolactone might actually produce antidepressant effects, for instance studies showing antidepressant-like effects of spironolactone in animals.

Pharmacology

Pharmacodynamics

The pharmacodynamics of spironolactone are characterized by high antimineralocorticoid activity, moderate antiandrogenic activity, and weak steroidogenesis inhibition, among other more minor activities. Spironolactone is a

prodrug A prodrug is a medication or compound that, after intake, is metabolized (i.e., converted within the body) into a pharmacologically active drug. Instead of administering a drug directly, a corresponding prodrug can be used to improve how the drug ...

, so most of its actions are actually mediated by its various active metabolites. The major active forms of spironolactone are

7α-thiomethylspironolactone 7α-Thiomethylspironolactone (7α-TMS; developmental code name SC-26519) is a steroidal antimineralocorticoid and antiandrogen of the spirolactone group and the major active metabolite of spironolactone. Other important metabolites of spiron ...

(7α-TMS) and

(7α-desthioacetyl-δ⁶-spironolactone). Spironolactone is a potent antimineralocorticoid. That is, it is an

antagonist An antagonist is a character in a story who is presented as the chief foe of the protagonist. Etymology The English word antagonist comes from the Greek ἀνταγωνιστής – ''antagonistēs'', "opponent, competitor, villain, enemy, riv ...

of the mineralocorticoid receptor (MR), the biological target of mineralocorticoids like

and

11-deoxycorticosterone 11-Deoxycorticosterone (DOC), or simply deoxycorticosterone, also known as 21-hydroxyprogesterone, as well as desoxycortone ( INN), deoxycortone, and cortexone, is a steroid hormone produced by the adrenal gland that possesses mineralocorticoi ...

. By blocking the MR, spironolactone inhibits the effects of mineralocorticoids in the body. The antimineralocorticoid activity of spironolactone is responsible for its therapeutic efficacy in the treatment of

, and ascites due to cirrhosis. It is also responsible for many of the side effects of spironolactone, such as urinary frequency, dehydration, hyponatremia, low blood pressure,

fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...

, dizziness,

metabolic acidosis Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-base balance. Metabolic acidosis has three main root causes: increased acid production, loss of bicarbonate, and a reduced ability of the kidneys ...

, decreased kidney function, and its risk of hyperkalemia. Due to the antimineralocorticoid activity of spironolactone, levels of

are significantly increased by the medication, probably reflecting an attempt of the body to maintain homeostasis. Spironolactone is a moderate antiandrogen. That is, it is an

of the

androgen receptor The androgen receptor (AR), also known as NR3C4 (nuclear receptor subfamily 3, group C, member 4), is a type of nuclear receptor that is activated by binding any of the androgenic hormones, including testosterone and dihydrotestosterone in th ...

(AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT). By blocking the AR, spironolactone inhibits the effects of androgens in the body. The antiandrogenic activity of spironolactone is mainly responsible for its therapeutic efficacy in the treatment of androgen-dependent skin and hair conditions like acne, seborrhea, hirsutism, and pattern hair loss and hyperandrogenism in women, precocious puberty in boys with

testotoxicosis Familial male-limited precocious puberty, often abbreviated as FMPP, also known as familial sexual precocity or gonadotropin-independent testotoxicosis, is a form of gonadotropin-independent precocious puberty in which boys experience early onset ...

, and as a component of feminizing hormone therapy for transgender women. It is also primarily responsible for some of its side effects, like breast tenderness, gynecomastia, feminization, and demasculinization in men. Blockade of androgen signaling in the breast disinhibits the actions of estrogens in this tissue. Although useful as an antiandrogen in women, who have low testosterone levels compared to men, spironolactone is described as having relatively weak antiandrogenic activity. Spironolactone is a weak steroidogenesis inhibitor. That is, it inhibits steroidogenic enzymes, or enzymes involved in the production of steroid hormones. Spironolactone and/or its metabolites have been found '' in vitro'' to weakly inhibit a broad array of steroidogenic enzymes including cholesterol side-chain cleavage enzyme,

17α-hydroxylase Cytochrome P450 17A1 (steroid 17α-monooxygenase, 17α-hydroxylase, 17-alpha-hydroxylase, 17,20-lyase, 17,20-desmolase) is an enzyme of the hydroxylase type that in humans is encoded by the ''CYP17A1'' gene on chromosome 10. It is ubiquitously expr ...

17,20-lyase Cytochrome P450 17A1 (steroid 17α-monooxygenase, 17α-hydroxylase, 17-alpha-hydroxylase, 17,20-lyase, 17,20-desmolase) is an enzyme of the hydroxylase type that in humans is encoded by the ''CYP17A1'' gene on chromosome 10. It is ubiquitously exp ...

, 3β-hydroxysteroid dehydrogenase, 11β-hydroxylase,

21-hydroxylase Steroid 21-hydroxylase (also known as steroid 21-monooxygenase, cytochrome P450C21, 21α-hydroxylase and less commonly 21β-hydroxylase) is an enzyme that hydroxylates steroids at the C21 position and is involved in biosynthesis of aldosterone a ...

, and aldosterone synthase (18-hydroxylase). However, although very high doses of spironolactone can considerably decrease steroid hormone levels in animals, spironolactone has shown mixed and inconsistent effects on steroid hormone levels in clinical studies, even at high clinical doses. In any case, the levels of most steroid hormones, including testosterone and

, are usually unchanged by spironolactone in humans, which may in part be related to compensatory upregulation of their synthesis. The weak steroidogenesis inhibition of spironolactone might contribute to its antiandrogenic efficacy to some degree and may explain its side effect of menstrual irregularities in women. However, its androgen synthesis inhibition is probably clinically insignificant. Spironolactone has been found in some studies to increase levels of estradiol, an estrogen, although many other studies have found no changes in estradiol levels. The mechanism of how spironolactone increases estradiol levels is unclear, but it may involve inhibition of the inactivation of estradiol into estrone and enhancement of the peripheral conversion of testosterone into estradiol. It is notable that spironolactone has been found ''in vitro'' to act as a weak inhibitor of

17β-hydroxysteroid dehydrogenase 2 17β-Hydroxysteroid dehydrogenase 2 (17β-HSD2) is an enzyme of the 17β-hydroxysteroid dehydrogenase (17β-HSD) family that in humans is encoded by the ''HSD17B2'' gene. Function 17β-HSD2 is involved in inactivation of androgens and estrogens ...

, an enzyme that is involved in the conversion of estradiol into estrone. Increased levels of estradiol with spironolactone may be involved in its preservation of bone density and in its side effects such as breast tenderness, breast enlargement, and gynecomastia in women and men. In response to the antimineralocorticoid activity spironolactone, and in an attempt to maintain homeostasis, the body increases aldosterone production in the

. Some studies have found that levels of

, a glucocorticoid hormone that is also produced in the adrenal cortex, are increased as well. However, other clinical studies have found no change in cortisol levels with spironolactone, and those that have found increases often have observed only small changes. In accordance, spironolactone has not been associated with conventional glucocorticoid medication effects or side effects. Other activities of spironolactone may include very weak interactions with the estrogen and

progesterone receptor The progesterone receptor (PR), also known as NR3C3 or nuclear receptor subfamily 3, group C, member 3, is a protein found inside cells. It is activated by the steroid hormone progesterone. In humans, PR is encoded by a single ''PGR'' gene resid ...

s and

agonism Agonism (from Greek ἀγών '' agon'', "struggle") is a political and social theory that emphasizes the potentially positive aspects of certain forms of conflict. It accepts a permanent place for such conflict in the political sphere, but seeks ...

of the pregnane X receptor. These activities could contribute to the menstrual irregularities and breast side effects of spironolactone and to its drug interactions, respectively.

Pharmacokinetics

The

pharmacokinetics Pharmacokinetics (from Ancient Greek ''pharmakon'' "drug" and ''kinetikos'' "moving, putting in motion"; see chemical kinetics), sometimes abbreviated as PK, is a branch of pharmacology dedicated to determining the fate of substances administered ...

of spironolactone have not been studied well, which is in part because it is an old medication that was developed in the 1950s. Nonetheless, much has been elucidated about the pharmacokinetics of spironolactone over the decades.

Absorption

Spironolactone and metabolite levels after a single oral dose of 100 mg spironolactone

The bioavailability of spironolactone when taken by mouth is 60 to 90%. The bioavailability of spironolactone and its metabolites increases significantly (+22–95% increases in levels) when spironolactone is taken with food, although it is uncertain whether this further increases the therapeutic effects of the medication. The increase in bioavailability is thought to be due to promotion of the gastric dissolution and

absorption Absorption may refer to: Chemistry and biology * Absorption (biology), digestion **Absorption (small intestine) *Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials *Absorption (skin), a route by which ...

of spironolactone, as well as due to a decrease of the first-pass metabolism. The relationship between a single dose of spironolactone and plasma levels of

, a major active metabolite of spironolactone, has been found to be linear across a dose range of 25 to 200 mg spironolactone.

Steady-state concentration Pharmacokinetics (from Ancient Greek ''pharmakon'' "drug" and ''kinetikos'' "moving, putting in motion"; see chemical kinetics), sometimes abbreviated as PK, is a branch of pharmacology dedicated to determining the fate of substances administere ...

s of spironolactone are achieved within 8 to 10 days of treatment initiation. Little or no systemic

has been observed with topical spironolactone.

Distribution

Spironolactone and its metabolite canrenone are highly

plasma protein bound Plasma protein binding refers to the degree to which medications attach to proteins within the blood. A drug's efficiency may be affected by the degree to which it binds. The less bound a drug is, the more efficiently it can traverse or diffuse th ...

, with percentages of 88.0% and 99.2%, respectively. Spironolactone is bound equivalently to albumin and α₁-acid glycoprotein, while canrenone is bound only to albumin. Spironolactone and its metabolite 7α-thiospironolactone show very low or negligible affinity for sex hormone-binding globulin (SHBG). In accordance, a study of high-dosage spironolactone treatment found no change in steroid binding capacity related to SHBG or to corticosteroid-binding globulin (CBG), suggesting that spironolactone does not displace steroid hormones from their carrier proteins. This is in contradiction with widespread statements that spironolactone increases free estradiol levels by displacing estradiol from SHBG. Spironolactone appears to cross the

blood–brain barrier The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that prevents solutes in the circulating blood from ''non-selectively'' crossing into the extracellular fluid of ...

Metabolism

Spironolactone is rapidly and extensively metabolized in the liver upon oral administration and has a very short terminal half-life of 1.4 hours. The major

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

s of spironolactone are

(7α-TMS), 6β-hydroxy-7α-thiomethylspironolactone (6β-OH-7α-TMS), and

(7α-desthioacetyl-δ⁶-spironolactone). These metabolites have much longer elimination half-lives than spironolactone of 13.8 hours, 15.0 hours, and 16.5 hours, respectively, and are responsible for the therapeutic effects of the medication. As such, spironolactone is a

. The 7α-thiomethylated metabolites of spironolactone were not known for many years and it was originally thought that canrenone was the major active metabolite of the medication, but subsequent research identified 7α-TMS as the major metabolite. Other known but more minor metabolites of spironolactone include 7α-thiospironolactone (7α-TS), which is an important intermediate to the major metabolites of spironolactone, as well as the 7α-methyl ethyl ester of spironolactone and the 6β-hydroxy-7α-methyl ethyl ester of spironolactone. Spironolactone is

hydrolyzed Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...

or deacetylated at the thioester of the C7α position into 7α-TS by carboxylesterases. Following formation of 7α-TS, it is ''S''- oxygenated by flavin-containing monooxygenases to form an

electrophilic In chemistry, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. Because electrophiles accept electrons, they are Lewis acids. Most electrophiles are positively charged, have an atom that carri ...

sulfenic acid In chemistry, a sulfenic acid is an organosulfur compound and oxoacid with the general formula . It is the first member of the family of organosulfur oxoacids, which also include sulfinic acids () and sulfonic acids (), respectively. The base ...

. This metabolite is involved in the CYP450 inhibition of spironolactone, and also binds covalently to other proteins. 7α-TS is also ''S''- methylated into 7α-TMS, a transformation catalyzed by thiol ''S''-methyltransferase. Unlike the related medication eplerenone, spironolactone is said to not be metabolized by

. However, hepatic CYP3A4 is likely responsible for the 6β-

hydroxylation In chemistry, hydroxylation can refer to: *(i) most commonly, hydroxylation describes a chemical process that introduces a hydroxyl group () into an organic compound. *(ii) the ''degree of hydroxylation'' refers to the number of OH groups in a ...

of 7α-TMS into 6β-OH-7α-TMS. 7α-TMS may also be hydroxylated at the C3α and C3β positions. Spironolactone is

dethioacetylated In organic chemistry, thioesters are organosulfur compounds with the functional group . They are analogous to carboxylate esters () with the sulfur in the thioester playing the role of the linking oxygen in the carboxylate ester, as implied by ...

into canrenone. Finally, the C17 γ- lactone ring of spironolactone is hydrolyzed by the paraoxonase PON3. It was originally thought to be hydrolyzed by PON1, but this was due to contamination with PON3.

Elimination

The majority of spironolactone is eliminated by the kidneys, while minimal amounts are handled by biliary excretion.

Chemistry

Spironolactone, also known as ''7α-acetylthiospirolactone'', is a

17α-spirolactone Spirolactones are a class of functional group in organic chemistry featuring a cyclic ester attached spiro to another ring system. The name is also used to refer to a class of synthetic steroids, called steroid-17α-spirolactones, 17α-spirol ...

, or more simply a spirolactone. It can most appropriately be conceptualized as a derivative of

progesterone Progesterone (P4) is an endogenous steroid and progestogen sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species. It belongs to a group of steroid hormones called the progestogens and is the m ...

, itself also a potent antimineralocorticoid, in which a

hydroxyl group In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy g ...

has been

substituted A substitution reaction (also known as single displacement reaction or single substitution reaction) is a chemical reaction during which one functional group in a chemical compound is replaced by another functional group. Substitution reactions ar ...

at the C17α position (as in

17α-hydroxyprogesterone 17α-Hydroxyprogesterone (17α-OHP), also known as 17-OH progesterone (17-OHP), or hydroxyprogesterone (OHP), is an endogenous progestogen steroid hormone related to progesterone. It is also a chemical intermediate in the biosynthesis of many ot ...

), the

acetyl group In organic chemistry, acetyl is a functional group with the chemical formula and the structure . It is sometimes represented by the symbol Ac (not to be confused with the element actinium). In IUPAC nomenclature, acetyl is called ethanoyl, ...

at the C17β position has been cyclized with the C17α hydroxyl group to form a spiro 21-

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...

γ- lactone ring, and an acetyl thio group has been substituted in at the C7α position. These structural modifications of progesterone confer increased oral bioavailability and potency, potent antiandrogenic activity, and strongly reduced progestogenic activity. The C7α substitution is likely responsible for or involved in the antiandrogenic activity of spironolactone, as

7α-thioprogesterone 7α-Thioprogesterone (7α-TP4; developmental code name SC-8365; also known as 7α-mercaptopregn-4-ene-3,20-dione) is a synthetic, steroidal, and potent antimineralocorticoid (putative) and antiandrogen which was developed by G. D. Searle & Co a ...

(SC-8365), unlike progesterone, is an antiandrogen with similar affinity to the AR as that of spironolactone. In addition, the C7α substitution appears to be responsible for the loss of progestogenic activity and good oral bioavailability of spironolactone, as SC-5233, the analogue of spironolactone without a C7α substitution, has potent progestogenic activity but very poor oral bioavailability similarly to progesterone.

Names

Spironolactone is also known by the following equivalent chemical names: * 7α-Acetylthio-17α-hydroxy-3-oxopregn-4-ene-21-carboxylic acid γ-lactone * 7α-Acetylthio-3-oxo-17α-pregn-4-ene-21,17β-carbolactone * 3-(3-Oxo-7α-acetylthio-17β-hydroxyandrost-4-en-17α-yl)propionic acid lactone * 7α-Acetylthio-17α-(2-carboxyethyl)androst-4-en-17β-ol-3-one γ-lactone * 7α-Acetylthio-17α-(2-carboxyethyl)testosterone γ-lactone

Analogues

Spironolactone is closely related structurally to other clinically used spirolactones such as

, drospirenone, and eplerenone, as well as to the never-marketed spirolactones SC-5233 (6,7-dihydrocanrenone; 7α-desthioacetylspironolactone), SC-8109 (19-nor-6,7-dihydrocanrenone), spiroxasone, prorenone (SC-23133), mexrenone (SC-25152, ZK-32055), dicirenone (SC-26304), spirorenone (ZK-35973), and

mespirenone Mespirenone (INN) (developmental code name ZK-94679), also known as Δ1-15β,16β-methylenespironolactone, is a steroidal antimineralocorticoid of the spirolactone group related to spironolactone that was never marketed. Animal research found th ...

(ZK-94679).

Synthesis

Chemical syntheses As a topic of chemistry, chemical synthesis (or combination) is the artificial execution of chemical reactions to obtain one or several products. This occurs by physical and chemical manipulations usually involving one or more reactions. In moder ...

of spironolactone and its analogues and derivatives have been described and reviewed.

History

The

natriuretic Natriuresis is the process of sodium excretion in the urine through the action of the kidneys. It is promoted by ventricular and atrial natriuretic peptides as well as calcitonin, and inhibited by chemicals such as aldosterone. Natriuresis low ...

effects of

were demonstrated in 1955, and the development of spironolactone as a

synthetic Synthetic things are composed of multiple parts, often with the implication that they are artificial. In particular, 'synthetic' may refer to: Science * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic o ...

antimineralocorticoid analogue of progesterone shortly followed this. Spironolactone was first synthesized in 1957, was patented between 1958 and 1961, and was first marketed, as an antimineralocorticoid, in 1959. Gynecomastia was first reported with spironolactone in 1962, and the antiandrogenic activity of the medication was first described in 1969. This shortly followed the discovery in 1967 that gynecomastia is an important and major side effect of AR antagonists. Spironolactone was first studied in the treatment of hirsutism in women in 1978. It has since become the most widely used antiandrogen for dermatological indications in women in the United States. Spironolactone was first studied as an antiandrogen in transgender women in 1986, and has since become widely adopted for this purpose as well, particularly in the United States where cyproterone acetate is not available. Early oral spironolactone tablets showed poor absorption. The formulation was eventually changed to a micronized formulation with particle sizes of less than 50 μg, which resulted in approximately 4-fold increased potency.

Society and culture

Generic names

The English,

French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

, and generic name of the medication is ''spironolactone'' and this is its , , , , , and . Its name is ''spironolactonum'' in Latin, ''spironolacton'' in German, ''espironolactona'' in Spanish and Portuguese, and ''spironolattone'' in Italian (which is also its ). Spironolactone is also known by its developmental code names ''SC-9420'' and ''NSC-150339''.

Brand names

Spironolactone is marketed under a large number of brand names throughout the world. The major brand name of spironolactone is Aldactone. Other important brand names include Aldactone-A, Berlactone, CaroSpir, Espironolactona, Espironolactona Genfar, Novo-Spiroton, Prilactone ( veterinary), Spiractin, Spiridon, Spirix, Spiroctan, Spiroderm (discontinued), Spirogamma, Spirohexal, Spirolon, Spirolone, Spiron, Spironolactone Actavis, Spironolactone Orion, Spironolactone Teva, Spirotone, Tempora (veterinary), Uractone, Uractonum, Verospiron, and Vivitar. Spironolactone is also formulated in combination with a variety of other medications, including with hydrochlorothiazide as Aldactazide, with hydroflumethiazide as Aldactide, Lasilacton, Lasilactone, and Spiromide, with

altizide Altizide is a thiazide diuretic. In combination with spironolactone it is sold under the brand name of ''Aldactacine'' and ''Aldactazine'' by Pfizer Pfizer Inc. ( ) is an American multinational pharmaceutical and biotechnology corporation ...

as Aldactacine and Aldactazine, with furosemide as Fruselac, with benazepril as Cardalis (veterinary), with metolazone as Metolactone, with bendroflumethiazide as Sali-Aldopur, and with torasemide as Dytor Plus, Torlactone, and Zator Plus.

Availability

Spironolactone is marketed widely throughout the world and is available in almost every country, including in the United States, Canada, the United Kingdom, other European countries,

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, New Zealand, South Africa,

Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...

and South America, and East and Southeast Asia.

Usage

There was a total of 17.2 million prescriptions for spironolactone in the United States between the beginning of 2003 and the end of 2005. There was a total of 12.0 million prescriptions for spironolactone in the United States in 2016 alone. It was the 66th top prescribed medication in the United States in 2016.

Research

Prostate conditions

Spironolactone has been studied at a high dosage in the treatment of benign prostatic hyperplasia (BPH; enlarged prostate). It was found to be better than placebo in terms of symptom relief following three months of treatment. However, this was not maintained after six months of treatment, by which point the improvements had largely disappeared. Moreover, no difference was observed between spironolactone and placebo with regard to volume of residual urine or prostate size. Gynecomastia was observed in about 5% of people. On the basis of these results, it has been said that spironolactone has no place in the treatment of BPH. Spironolactone has been studied and used limitedly in the treatment of

prostate cancer Prostate cancer is cancer of the prostate. Prostate cancer is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that sur ...

Epstein–Barr virus

Spironolactone has been found to block Epstein–Barr virus (EBV) production and that of other human herpesviruses by inhibiting the function of an EBV protein SM, which is essential for infectious virus production. This effect of spironolactone was determined to be independent of its antimineralocorticoid actions. Thus, spironolactone or compounds based on it have the potential to yield novel antiviral medications with a distinct mechanism of action and limited toxicity.

Other conditions

Spironolactone has been studied in the treatment of rosacea in both males and females. Spironolactone has been studied in

fibromyalgia Fibromyalgia (FM) is a medical condition defined by the presence of chronic widespread pain, fatigue, waking unrefreshed, cognitive symptoms, lower abdominal pain or cramps, and depression. Other symptoms include insomnia and a general hyp ...

in women. It has also been studied in bulimia nervosa in women, but was not found to be effective.

References

External links

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