Testosterone undecanoate, sold under the brand name Nebido among others, is an

androgen An androgen (from Greek ''andr-'', the stem of the word meaning ) is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes ...

and

anabolic steroid Anabolic steroids, also known as anabolic-androgenic steroids (AAS), are a class of drugs that are structurally related to testosterone, the main male sex hormone, and produce effects by binding to the androgen receptor (AR). Anabolism, Anaboli ...

(AAS)

medication Medication (also called medicament, medicine, pharmaceutical drug, medicinal product, medicinal drug or simply drug) is a drug used to medical diagnosis, diagnose, cure, treat, or preventive medicine, prevent disease. Drug therapy (pharmaco ...

that is used mainly in the treatment of low testosterone levels in men, It is taken

by mouth Oral administration is a route of administration whereby a substance is taken through the Human mouth, mouth, swallowed, and then processed via the digestive system. This is a common route of administration for many medications. Oral administ ...

or given by injection into muscle.

Side effect In medicine, a side effect is an effect of the use of a medicinal drug or other treatment, usually adverse but sometimes beneficial, that is unintended. Herbal and traditional medicines also have side effects. A drug or procedure usually use ...

s of testosterone undecanoate include

symptom Signs and symptoms are diagnostic indications of an illness, injury, or condition. Signs are objective and externally observable; symptoms are a person's reported subjective experiences. A sign for example may be a higher or lower temperature ...

s of

masculinization Virilization or masculinization is the biological development of adult male characteristics in young males or females. Most of the changes of virilization are produced by androgens. Virilization is a medical term commonly used in three medical a ...

acne Acne ( ), also known as ''acne vulgaris'', is a long-term Cutaneous condition, skin condition that occurs when Keratinocyte, dead skin cells and Sebum, oil from the skin clog hair follicles. Typical features of the condition include comedo, ...

, increased hair growth,

voice changes The human voice consists of sound made by a human being using the vocal tract, including talking, singing, laughing, crying, screaming, shouting, humming or yelling. The human voice frequency is specifically a part of human sound production in ...

hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...

, elevated liver enzymes, hypertriglyceridemia, and increased

sexual desire Sexual desire is an emotion and motivational state characterized by an interest in sexual objects or activities, or by a drive to seek out sexual objects or to engage in sexual activities. It is an aspect of sexuality, which varies significantly ...

. The drug is a

prodrug A prodrug is a pharmacologically inactive 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 ...

of testosterone, the

biological ligand In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. The etymology stems from Latin ''ligare'', which means 'to bind'. In protein-ligand binding, the ligand is usually a ...

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) and hence is an androgen and anabolic steroid. It has strong

ic effects and moderate

anabolic Anabolism () is the set of metabolic pathways that construct macromolecules like DNA or RNA from smaller units. These reactions require energy, known also as an endergonic process. Anabolism is the building-up aspect of metabolism, whereas catab ...

effects, which make it useful for producing masculinization and suitable for

androgen replacement therapy Androgen replacement therapy (ART), often referred to as testosterone replacement therapy (TRT), is a form of hormone therapy in which androgens, often testosterone, are supplemented or replaced. It typically involves the administration of tes ...

. Testosterone undecanoate is a

testosterone ester This is a list of androgen esters, including esters (as well as ethers) of natural androgens like testosterone and dihydrotestosterone (DHT) and synthetic anabolic–androgenic steroids (AAS) like nandrolone (19-nortestosterone). Esters ...

and a

testosterone Testosterone is the primary male sex hormone and androgen in Male, males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testicles and prostate, as well as promoting se ...

in the body. Because of this, it is considered to be a natural and bioidentical form of testosterone. Testosterone undecanoate was introduced in China for use by injection and in the European Union for use by mouth in the 1970s. It became available for use by injection in the European Union in the early to mid 2000s and in the United States in 2014. Formulations for use by mouth are approved in the United States. Along with

testosterone enanthate Testosterone enanthate is used in the treatment of low testosterone levels in men. It is also used in hormone therapy for women and transgender men. It is given by injection into muscle or subcutaneously usually once every one to four weeks. ...

testosterone cypionate Testosterone cypionate, sold under the brand name Depo-Testosterone among others, is an androgen and anabolic steroid (AAS) medication which is used mainly in the treatment of low testosterone levels in men, including hormone therapy for transg ...

, and

testosterone propionate Testosterone propionate, sold under the brand name Testoviron among others, is an androgen and anabolic steroid (AAS) medication which is used mainly in the treatment of low testosterone levels in men. It has also been used to treat breast cance ...

, testosterone undecanoate is one of the most widely used testosterone esters. However, it has advantages over other testosterone esters in that it can be taken by mouth and in that it has a far longer duration when given by injection. In addition to its medical use, testosterone undecanoate is used to improve physique and performance. The drug is a

controlled substance A controlled substance is generally a drug or chemical whose manufacture, possession and use is regulated by a government, such as illicitly used drugs or prescription medications that are designated by law. Some treaties, notably the Sing ...

in many countries. Oral administration of testosterone undecanoate is an effective method to achieve therapeutic physiological levels of serum testosterone in patients with hypogonadism. In addition, oral therapy has been found to have a positive impact in these patients on quality of life factors such as sexual function, mood, and mental status, as documented in various studies.

Medical uses

Testosterone undecanoate is

indicated In medicine, an indication is a valid reason to use a certain test, medication, procedure, or surgery. There can be multiple indications to use a procedure or medication. An indication can commonly be confused with the term diagnosis. A diagnosis ...

for testosterone replacement therapy in adult males for conditions associated with a deficiency or absence of endogenous testosterone.

Side effects

s of testosterone undecanoate include

virilization Virilization or masculinization is the biological development of adult male characteristics in young males or females. Most of the changes of virilization are produced by androgens. Virilization is a medical term commonly used in three medical a ...

among others.

Anaphylaxis

The Reandron 1000 formulation (Aveed in the United States) contains 1,000 mg of testosterone undecanoate suspended in 4 ml

castor oil Castor oil is a vegetable oil pressed from castor beans, the seeds of the plant ''Ricinus communis''. The seeds are 40 to 60 percent oil. It is a colourless or pale yellow liquid with a distinct taste and odor. Its boiling point is and its den ...

with

benzyl benzoate Benzyl benzoate is an organic compound which is used as a medication and insect repellent. As a medication it is used to treat scabies and lice. For scabies either permethrin or malathion is typically preferred. It is applied to the skin as a l ...

for

solubilization Micellar solubilization (solubilization) is the process of incorporating the solubilizate (the component that undergoes solubilization) into or onto micelles. Solubilization may occur in a system consisting of a solvent, an association colloid (a ...

and as a

preservative A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or ...

, and is administered by

intramuscular injection Intramuscular injection, often abbreviated IM, is the medical injection, injection of a substance into a muscle. In medicine, it is one of several methods for parenteral, parenteral administration of medications. Intramuscular injection may be ...

. As an

excipient An excipient is a substance formulated alongside the active ingredient of a medication. They may be used to enhance the active ingredient’s therapeutic properties; to facilitate drug absorption; to reduce viscosity; to enhance solubility; to i ...

in Reandron 1000, benzyl benzoate has been reported as a cause of

anaphylaxis Anaphylaxis (Greek: 'up' + 'guarding') is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of the use of emergency medication on site. It typicall ...

(a serious life-threatening

allergic reaction Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include Allergic rhinitis, hay fever, Food allergy, food al ...

) in a case in

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

Bayer Bayer AG (English: , commonly pronounced ; ) is a German multinational pharmaceutical and biotechnology company and is one of the largest pharmaceutical companies and biomedical companies in the world. Headquartered in Leverkusen, Bayer' ...

includes this report in information for health professionals and recommends that physicians "should be aware of the potential for serious allergic reactions" to preparations of this type. In Australia, reports to the Adverse Drug Reactions Advisory Committee (ADRAC), which evaluates reports of

adverse drug reactions An adverse drug reaction (ADR) is a harmful, unintended result caused by taking medication. ADRs may occur following a single dose or prolonged administration of a drug or may result from the combination of two or more drugs. The meaning of this ...

for the

Therapeutic Goods Administration The Therapeutic Goods Administration (TGA) is the medicine and therapeutic regulatory agency of the Australian Government. As part of the Department of Health, Disability and Ageing, the TGA regulates the safety, quality, efficacy and advertisi ...

(TGA), show several reports of allergic reactions since the anaphylaxis case from 2011.

Pharmacology

Pharmacodynamics

Testosterone undecanoate is a

of testosterone and is an androgen and

anabolic–androgenic steroid Anabolic steroids, also known as anabolic-androgenic steroids (AAS), are a class of drugs that are structurally related to testosterone, the main male sex hormone, and produce effects by binding to the androgen receptor (AR). Anabolism, Anaboli ...

(AAS). That is, it is an

agonist An agonist is a chemical that activates a Receptor (biochemistry), receptor to produce a biological response. Receptors are Cell (biology), cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an R ...

of the

(AR).

Pharmacokinetics

Testosterone undecanoate has a very long

elimination half-life Biological half-life (elimination half-life, pharmacological half-life) is the time taken for concentration of a biological substance (such as a medication) to decrease from its maximum concentration ( Cmax) to half of Cmax in the blood plasma. ...

and

mean residence time The residence time of a fluid parcel is the total time that the parcel has spent inside a control volume (e.g.: a chemical reactor, a lake, a human body). The residence time of a set of parcels is quantified in terms of the frequency distribution ...

when given as a

depot Depot may refer to: Places * Depot, Poland, a village * Depot Glacier (disambiguation) * Depot Island (disambiguation) * Depot Nunatak * Depot Peak Brands and enterprises * Maxwell Street Depot, a restaurant in Chicago, United States * Of ...

. Its elimination half-life is 20.9 days and its

is 34.9 days in

tea seed oil Tea seed oil (also known as ''camellia oil'', ''camellia seed oil'', ''teanut oil'') is an edible plant oil. It is obtained from the seeds of '' Camellia oleifera''. ''Camellia sasanqua'' is also given as a source of 'tea seed oil. Description ...

, while its elimination half-life is 33.9 days and its mean residence time is 36.0 days in

. These values are substantially longer than those of

(which, in castor oil, has values of 4.5 days and 8.5 days, respectively). Testosterone undecaondate has very low bioavailability when taken orally, only about 3-7% in men and 4-10% in women. This bioavailability is increased with food, especially foods containing fat, thus it is typically recommended to be taken with a meal. It is absorbed through the lymphatic system (90-100%) and peak serum levels are reached after about 3-5 hours. From there, plasma levels decline, typically reaching pre-dose levels after 6-12 hours. The elimination half-life via the oral route has been stated to be 1.6 hours, with a

of 3.7 hours. However, there is a large amount of individual variability in its duration of action. For this reason it is often dosed twice or even three times a day. Testosterone undecanoate is metabolized partially in the intestinal wall into 5-alpha-dihydrotestosterone undecanoate (DHTU). In the blood, non-specific esterases metabolize testosterone undecanoate into testosterone and DHTU into

dihydrotestosterone Dihydrotestosterone (DHT, 5α-dihydrotestosterone, 5α-DHT, androstanolone or stanolone) is an endogenous androgen sex steroid and hormone primarily involved in the growth and repair of the prostate and the penis, as well as the production o ...

(DHT). Thus, testosterone undecanoate increases plasma levels of both testerone and DHT. The fact the conversion happens in the blood complicates the accurate measurement of blood levels of testosterone induced by the drug, as the conversion continues to occur while blood samples are being prepared for assay. Ideally, enzyme inhibitors should be used to properly assay the blood testosterone levels induced by testosterone undecanoate.

Chemistry

Testosterone undecanoate, or testosterone 17β-undecanoate, is a

synthetic Synthetic may refer to: Science * Synthetic biology * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic elements, chemical elements that are not naturally found on Earth and therefore have to be created in ...

androstane Androstane is a C19 steroidal hydrocarbon with a gonane core. Androstane can exist as either of two isomers, known as 5α-androstane and 5β-androstane. File:androstane.png, 5α-Androstane File:androstane 5beta.png, 5β-Androstane Pharmacolog ...

steroid A steroid is an organic compound with four fused compound, fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes t ...

and a

derivative In mathematics, the derivative is a fundamental tool that quantifies the sensitivity to change of a function's output with respect to its input. The derivative of a function of a single variable at a chosen input value, when it exists, is t ...

. It is an

androgen ester An androgen or anabolic steroid ester is an ester of an androgen/anabolic steroid (AAS) such as the natural testosterone or dihydrotestosterone (DHT) or the synthetic nandrolone (19-nortestosterone). Esterification renders AAS into metabolism-res ...

; specifically, it is the C17β undecylate (undecanoate)

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

of testosterone. A related testosterone ester with a similarly very long duration is

testosterone buciclate Testosterone buciclate (developmental code names 20 Aet-1, CDB-1781) is a synthetic, injected anabolic–androgenic steroid (AAS) which was never marketed. It was developed in collaboration by the Contraceptive Development Branch (CDB) of the Na ...

. The first commercialized preparation of oral testosterone undecanoate had it dissolved in oleic acid. This formulation had to be refrigerated in the pharmacy for reasons of stability and would only last about three months at room temperature. A newer more stable pharmaceutical formulation with

and propylene glycol laurate has since been developed. This new formulation can be stored at room temperature for three years. A novel self-emulsifying formulation of oral testosterone undecanoate in 300-mg capsules for use once per day has been under development.<

History

In the late 1970s, testosterone undecanoate was introduced for oral use in

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

, although intramuscular testosterone undecanoate had already been in use in

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

for several years. Intramuscular testosterone undecanoate was not introduced in Europe and the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

until much later, in the early to mid 2000s and 2014, respectively. Testosterone undecanoate was approved in the United States only in 2014 after three previous rejections due to safety concerns.

Society and culture

Generic names

''Testosterone undecanoate'' is the generic name of the drug and its and . It is also referred to as ''testosterone undecylate''.

Brand names

Testosterone undecanoate is or has been marketed under a variety of brand names, including Andriol, Androxon, Aveed, Cernos Depot, Jatenzo, Kyzatrex, Nebido, Nebido-R, Panteston, Reandron 1000, Restandol, Sustanon 250, Undecanoate 250, and Undestor.

Availability

Oral testosterone undecanoate is available in Europe, Mexico, Asia, and the United States. Intramuscular testosterone undecanoate has been approved worldwide, including the European Union, Russia, and the United States. Intramuscular testosterone undecanoate is marketed as Nebido in Europe and as Aveed in the United States while oral testosterone undecanoate is marketed as Andriol.

Legal status

Testosterone undecanoate, along with other AAS, is a schedule III

in the

under the

Controlled Substances Act The Controlled Substances Act (CSA) is the statute establishing federal government of the United States, federal drug policy of the United States, U.S. drug policy under which the manufacture, importation, possession, use, and distribution of ...

and a schedule IV controlled substance in

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

under the

Controlled Drugs and Substances Act Control may refer to: Basic meanings Economics and business * Control (management), an element of management * Control, an element of management accounting * Comptroller (or controller), a senior financial officer in an organization * Controll ...

. In March 2019, the US

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...

approved testosterone undecanoate (Jatenzo), an oral testosterone capsule to treat men with certain forms of

hypogonadism Hypogonadism means diminished functional activity of the human gonad, gonads—the testicles or the ovary, ovaries—that may result in diminished biosynthesis, production of sex hormones. Low androgen (e.g., testosterone) levels are referred t ...

. These men have low testosterone levels due to specific medical conditions, such as genetic disorders like Klinefelter syndrome or tumors that have damaged the pituitary gland. The FDA granted the approval of Jatenzo to Clarus Therapeutics. In March 2022, testosterone undecanoate (Tlando) was approved for medical use in the United States. In July 2022, Kyzatrex, an oral testosterone undecanoate capsule, was approved for medical use in the United States. The FDA granted the approval of Kyzatrex to Marius Pharmaceuticals.

Research

Non-alcoholic steatohepatitis

In 2013, a phase II

clinical trial Clinical trials are prospective biomedical or behavioral research studies on human subject research, human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel v ...

testing intramuscular testosterone undecanoate for the treatment of

non-alcoholic steatohepatitis An alcohol-free or non-alcoholic drink, also known as a temperance drink, is a version of an alcoholic drink made without alcohol, or with the alcohol removed or reduced to almost zero. These may take the form of a non-alcoholic mixed drink or n ...

(NASH) was initiated in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

. In the United States in 2018, Lipocine Inc. began investigating the potential of using an oral testosterone undecanoate formulation, known as LPCN-1144, in patients with NASH.

Osteoporosis

In 2013, a study aimed to evaluate the efficacy of testosterone undecanoate therapy on bone mineral density (BMD) and biochemical markers of bone turnover in elderly males with

osteoporosis Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to more porous bone, and consequent increase in Bone fracture, fracture risk. It is the most common reason f ...

and low serum testosterone levels. They study found that administering low-dose testosterone undecanoate (TU) at a rate of 20 mg per day to elderly men with low serum testosterone and osteoporosis effectively increases bone mineral density in the lumbar spine and femoral neck, and improves bone turnover, similar to the standard-dose TU (40 mg, per day) treatment. The treatment did not exhibit any adverse side effects on the prostate gland, including prostate-specific antigen. Therefore, low-dose TU appears to be a safe and cost-effective protocol for treating elderly male osteoporosis. However, further clinical trials with larger sample sizes, multiple centers, and long-term follow-ups are required to determine the efficacy and safety of low-dose testosterone undecanoate treatment in elderly male osteoporosis with low serum testosterone.

Health implications

Risks associated with treatment of late-onset hypogonadism

There is a potential concern in the medical community that the administration of testosterone therapy for the treatment of

late-onset hypogonadism Late-onset hypogonadism (LOH) or testosterone deficiency syndrome (TDS) is a condition in older men characterized by measurably low testosterone levels and clinical symptoms mostly of a sexual nature, including decreased desire for mating, fewer s ...

may escalate the risks associated with

benign prostatic hyperplasia Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the prostate gland. Symptoms may include frequent urination, trouble starting to urinate, weak stream, urinary retention, inability t ...

prostate cancer Prostate cancer is the neoplasm, uncontrolled growth of cells in the prostate, a gland in the male reproductive system below the bladder. Abnormal growth of the prostate tissue is usually detected through Screening (medicine), screening tests, ...

and heart diseases.

Body composition

In 2020, a study that evaluated the effects of testosterone therapy in men with testosterone deficiency and varying degrees of weight (normal weight, overweight, and obesity) on anthropometric and metabolic parameters found that long-term testosterone undecanoate therapy in hypogonadal men, regardless of their weight at the start of the study, led to improvements in several body composition parameters, including body weight, waist circumference, and body mass index. Additionally, testosterone undecanoate therapy was found to lower fasting blood glucose and HbA1c levels and improve lipid profiles in this population.

Bone density

There have been several studies that evaluate the effect of testosterone therapy on bone density or bone mineral density (BMD). One study concluded that long-term testosterone replacement therapy (TRT) in middle-aged men with

(LOH) and metabolic syndrome (MS) led to a significant increase in both vertebral and femoral bone mineral density (BMD) after 36 months of treatment, as measured by dual-energy x-ray absorptiometry. The TRT treatment was shown to induce a 5% per year increase in BMD without changes in body mass index (BMI). The study suggests that long-term TRT could be beneficial for improving bone health in middle-aged men with LOH and MS, even in the absence of osteoporosis.

References

{{Authority control Anabolic–androgenic steroids Androstanes Drugs developed by Bayer Contraception for males Ketones Testosterone esters Undecanoate esters