Etonogestrel is a medication which is used as a means of

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 ...

for women. It is available as an implant placed under the skin of the upper arm under the brand names Nexplanon and Implanon, and in combination with ethinylestradiol, an

estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...

, as a vaginal ring under the brand names ''NuvaRing'' and ''Circlet''. Etonogestrel is effective as a means of birth control and lasts at least three or four years with some data showing effectiveness for five years. Following removal,

fertility Fertility is the capability to produce offspring through reproduction following the onset of sexual maturity. The fertility rate is the average number of children born by a female during her lifetime and is quantified demographically. Ferti ...

quickly returns. Side effects of etonogestrel include menstrual irregularities, breast tenderness, mood changes,

acne Acne, also known as ''acne vulgaris'', is a long-term skin condition that occurs when dead skin cells and oil from the skin clog hair follicles. Typical features of the condition include blackheads or whiteheads, pimples, oily skin, and ...

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

vaginitis Vaginitis, also known as vulvovaginitis, is inflammation of the vagina and vulva. Symptoms may include itching, burning, pain, discharge, and a bad smell. Certain types of vaginitis may result in complications during pregnancy. The three ma ...

, and others. Etonogestrel is 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 female sex hormone progesterone in the body. A progestin is a ''synthetic'' progestogen. Pro ...

, or 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 ...

progestogen, and hence is an

agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ag ...

of the progesterone receptor, the biological target of progestogens like

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 majo ...

. It works by stopping ovulation, thickening the

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...

around the opening of the

cervix The cervix or cervix uteri (Latin, 'neck of the uterus') is the lower part of the uterus (womb) in the human female reproductive system. The cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape, which changes during ...

, and altering the lining of the

uterus The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The ...

. It has very weak androgenic and glucocorticoid activity and no other important hormonal activity. Etonogestrel was patented in 1972 and introduced for medical use in 1998. It became available in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

in 2006. Etonogestrel implants are approved in more than 90 countries and used by about three million women globally as of 2010. A closely related and more widely known and used progestin, desogestrel, 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 dru ...

of etonogestrel in the body.

Medical uses

Etonogestrel is used in hormonal contraception in form of the etonogestrel contraceptive implant and the contraceptive vaginal ring (brand names NuvaRing, Circlet), the latter in combination with ethinylestradiol. Etonogestrel birth control implants are a type of long-acting reversible contraception, which has been shown to be one of the most effective form of birth control. The failure rate of the implants is 0.05% for both perfect use and typical use because the method requires no user action after placement. Studies of one type, which include over 2,467 women-years of exposure, found no pregnancies. Other studies have found some failures with this method, some attributed to failures of the method itself and others to improper placement, drug interactions, or conception prior to method insertion. In comparison, tubal sterilization has a failure rate of 0.5% and IUDs have a failure rate of 0.2–0.8%. A single implant is approved for three years with data showing effectiveness for five years.

Contraindications

Women should not use implants if they: * are, or think they are, pregnant * are allergic to etonogestrel * have vaginal bleeding that has not been explained * have some forms of severe liver disease. Women should not use combined hormone contraceptives (CHC) if they have migraines with auras. A full list of contraindications can be found in the WHO ''Medical Eligibility Criteria for Contraceptive Use 2015'' and the CDC ''United States Medical Eligibility Criteria for Contraceptive Use 2016''.

Side effects

Irregular bleeding and spotting: Many women will experience some type of irregular, unpredictable, prolonged, frequent, or infrequent bleeding. Some women also experience amenorrhea. For some women, prolonged bleeding will decline after the first three months of use. However, other women may experience this bleeding pattern through all five years of use. While these patterns are not dangerous, they are the most common reason that women give for discontinuing the use of the implant. After removal, bleeding patterns return to previous patterns in most women. Insertion complications: Some minor side effects such as bruising, skin irritation, or pain around the insertion site are common. However, there are some rare complications that can occur, such as infection or expulsion. In some cases, a serious complication occurs when the provider fails to insert, and the rod is left in the inserter. An Australian study reported 84 pregnancies as a result of such failure. Migration: Although very rare, the rod can sometimes move slightly within the arm. This can make removal more difficult. It is possible that insertion in the same site as a previous implant increases the likelihood of migration. Rods can be located only through high-frequency ultrasound or magnetic resonance imaging (MRI). It can be located using traditional X-ray or CT-scan because of the inclusion of barium sulphate. There have been rare reports of implants having reached the lung via the pulmonary artery. Correct subdermal insertion over the triceps muscle reduces the risk of these events. Possible weight gain: Some women may experience slight weight gain when using the implant. However, current studies are not conclusive because they do not compare the weight of women using implants with a control group of women not using the implant. The average increase in body weight in studies was less than 5 pounds (2,25 kg) over 2 years. Ovarian cysts: A small portion of women using implants and other contraceptive implants develop ovarian cysts. Usually these cysts will disappear without treatment. Pregnancy: it is recommended that implants be removed if a pregnancy does occur. However, there is no evidence to suggest that the implant has a negative effect on pregnancy or a developing fetus. Acne: Acne has been self-reported to be a side effect, and is listed as a side effect by the FDA. However, a study of users found that a majority of users with acne before their insertion reported that their acne had decreased, and only 16% of those who did not have acne before insertion developed acne. Other possible symptoms: Other symptoms that have been reported in trials of implants include headache, emotional lability, abdominal pain, loss of libido, and vaginal dryness. However, there have been no studies that conclusively determine that these symptoms are caused by the implant.

Overdose

No serious side effects are expected when overdosing contraceptives in general.

Interactions

Efavirenz Efavirenz (EFV), sold under the brand names Sustiva among others, is an antiretroviral medication used to treat and prevent HIV/AIDS. It is generally recommended for use with other antiretrovirals. It may be used for prevention after a needle ...

, an inducer of the liver enzyme

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 ...

, appears to decrease etonogestrel levels and increase rates of undesired pregnancy among implant users. Similar effects are expected for other CYP3A4 inducers, but it is not known whether these are clinically relevant. The opposite is true of CYP3A4 inhibitors such as

ketoconazole Ketoconazole, sold under the brand name Nizoral among others, is an antiandrogen and antifungal medication used to treat a number of fungal infections. Applied to the skin it is used for fungal skin infections such as tinea, cutaneous ca ...

, itraconazole and clarithromycin: they might increase etonogestrel concentrations in the body.

Device description

Nexplanon/Implanon consists of a single rod made of ethylene vinylacetate copolymer that is 4 cm long and 2mm in diameter. It is similar to a matchstick in size. The rod contains 68 mg of etonogestrel (sometimes called 3-keto-destrogestrel), a type of progestin. Peak serum etonogestrel concentrations have been found to reach 781–894 pg/mL in the first few weeks, gradually decreasing to 192–261 pg/mL after 1 year, 154–194 pg/mL after 2 years, and 156–177 pg/mL after 3 years, maintaining ovulation suppression and contraceptive efficacy. Serum levels maintain relatively stable through 36 months, which implies that the method may be effective for longer than 3 years. Although not formally approved by the manufacturer for more than 3 years, studies have shown it remains a highly effective contraceptive for 5 years. It is a type of progestogen-only contraception.

Insertion and removal

An experienced clinician must perform the insertion of implants to ensure proper insertion and minimize the risk of nerve damage or misplacement, which could result in pregnancy. Before insertion, the arm is washed with a cleaning solution and a local anesthetic is applied to the upper arm around the insertion area. A needle-like applicator is used to insert the rod under the skin into the subdermal tissue on the inner side of the arm posterior to the groove between the biceps and triceps muscles. The average time for insertion is 0.5 to 1 minute. A bandage should be kept on the insertion site for 24 hours afterwards. Bruising and mild discomfort are common after insertion. Serious insertion site complications such as infection can occur very rarely, in less than 1% of patients. If a woman receives an implant outside the first five days of her period, she should wait to have sex or use a backup method of contraception (such as a

condom A condom is a sheath-shaped Barrier contraception, barrier device used during sexual intercourse to reduce the probability of pregnancy or a Sexually transmitted disease, sexually transmitted infection (STI). There are both male and female con ...

female condom An internal condom (also known as a femidom or female condom) is a barrier device that is used during sexual intercourse as a barrier contraceptive to reduce the probability of pregnancy or a sexually transmitted infection (STI). Meant as an al ...

diaphragm Diaphragm may refer to: Anatomy * Thoracic diaphragm, a thin sheet of muscle between the thorax and the abdomen * Pelvic diaphragm or pelvic floor, a pelvic structure * Urogenital diaphragm or triangular ligament, a pelvic structure Other * Diap ...

, sponge, or emergency contraception) for the following week after insertion to prevent pregnancy. However, if the implant is inserted during the first five days of a woman's period, she is protected for that cycle and beyond.Bedsider (2010). "Implant." Retrieved from http://bedsider.org/methods/implant#how_to_tab on March 17, 2011. Implants can be removed at any time if pregnancy is desired. The rod must also be removed by an experienced clinician. At removal, a local anesthetic is again used around the implant area at the distal end. If the provider cannot feel the implant, imaging tests may be necessary to locate the rod before it can be removed. A small incision is made in the skin over the end of the implant site. In some cases, a fibrous sheath may have formed around the implant, in which case the sheath must be incised. The implant is removed using forceps. The removal procedure lasts, on average, 3 to 3.5 minutes.

Fertility after removal

Within a week of removal, the hormones from the device leave the body and etonogestrel is undetectable in most users. Most women will begin to ovulate within six weeks of removal. Fertility levels will return to what they were before implant insertion.

Differences

Nexplanon and Implanon NXT are essentially identical to Implanon except Nexplanon and Implanon NXT have 15 mg of

barium sulphate Barium sulfate (or sulphate) is the inorganic compound with the chemical formula Ba SO4. It is a white crystalline solid that is odorless and insoluble in water. It occurs as the mineral barite, which is the main commercial source of barium and ...

added to the core, so it is detectable by x-ray. Nexplanon and Implanon NXT also has a pre-loaded applicator for easier insertion.

Pharmacology

The mechanism of action of progestin only contraceptives depends on the progestin activity and dose. Intermediate dose progestin-only contraceptives like Nexplanon or Implanon allow some follicular development but inhibit ovulation in almost all cycles as the primary mechanism of action. Ovulation was not observed in studies of Implanon in the first two years of use and only rarely in the third year with no pregnancies. A secondary mechanism of action is the progestogenic increase in cervical mucus viscosity which inhibits sperm penetration. Hormonal contraceptives also have effects on the endometrium that theoretically could affect implantation, however no scientific evidence indicates that prevention of implantation actually results from their use.

Pharmacodynamics

Etonogestrel is a progestogen, or an

of the progesterone receptor. It is less androgenic than

levonorgestrel Levonorgestrel is a hormonal medication which is used in a number of birth control methods. It is combined with an estrogen to make combination birth control pills. As an emergency birth control, sold under the brand name Plan B One-Step amon ...

and norethisterone, and it does not cause a decrease in sex hormone-binding globulin levels. However, it is still associated with

in up to 13.5% of patients when used as an implant, though this side effect only accounts for 1.3% of premature removals of the implant. In addition to its progestogenic and weak androgenic activity, etonogestrel binds to the glucocorticoid receptor with about 14% of the affinity of

dexamethasone Dexamethasone is a glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive lung disease, croup, brain swelling, eye pain following eye surgery, superior vena ...

(relative to 1% for levonorgestrel) and has very weak glucocorticoid activity. Etonogestrel has no other hormonal activity (e.g.,

ic, antimineralocorticoid). Some inhibition of 5α-reductase and hepatic

cytochrome P450 Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various co ...

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

s has been observed with etonogestrel ''

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology a ...

'', similarly to other

19-nortestosterone Nandrolone, also known as 19-nortestosterone, is an androgen and anabolic steroid (AAS) which is used in the form of esters such as nandrolone decanoate (brand name Deca-Durabolin) and nandrolone phenylpropionate (brand name Durabolin). Nandrolon ...

progestins.

Pharmacokinetics

The bioavailability of etonogestrel when given as a subcutaneous implant or as a vaginal ring is 100%.

Steady-state In systems theory, a system or a process is in a steady state if the variables (called state variables) which define the behavior of the system or the process are unchanging in time. In continuous time, this means that for those properties '' ...

levels of etonogestrel are achieved within one week upon insertion as an implant or vaginal ring. The mean

volume of distribution In pharmacology, the volume of distribution (VD, also known as apparent volume of distribution, literally, ''volume of dilution'') is the theoretical volume that would be necessary to contain the total amount of an administered drug at the same c ...

of etonogestrel is 201 L. The plasma protein binding of the medication is at least 98%, with 66% bound to

albumin Albumin is a family of globular proteins, the most common of which are the serum albumins. All the proteins of the albumin family are water- soluble, moderately soluble in concentrated salt solutions, and experience heat denaturation. Album ...

and 32% bound to sex hormone-binding globulin. Etonogestrel is

metabolized Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

in the

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it i ...

. The

biological activity In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or ...

of its

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, ...

s is unknown. The

elimination half-life Biological half-life (also known as elimination half-life, pharmacologic 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 b ...

of etonogestrel is about 25 to 29 hours. Following removal of an etonogestrel-containing implant, levels of the medication were below the limits of assay detection by one week. The major portion of etonogestrel is eliminated in

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellul ...

and a minor portion is eliminated in

feces Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a rela ...

Chemistry

Etonogestrel, also known as 11-methylene-17α-ethynyl-18-methyl-19-nortestosterone or as 11-methylene-17α-ethynyl-18-methylestr-4-en-17β-ol-3-one, is a

estrane Estrane is a C18 steroid derivative, with a gonane core. ''Estrenes'' are estrane derivatives that contain a double bond, with an example being nandrolone. ''Estratrienes'' (estrins) are estrane derivatives that contain three double bonds, for i ...

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 ...

and a

derivative In mathematics, the derivative of a function of a real variable measures the sensitivity to change of the function value (output value) with respect to a change in its argument (input value). Derivatives are a fundamental tool of calculus. ...

testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...

. It is more specifically a derivative of norethisterone (17α-ethynyl-19-nortestosterone) and is a member of the

gonane Gonane is a chemical compound with formula , whose molecule can be described as three molecules or entities of cyclohexane and one of cyclopentane, fused in a particular way. More specifically, the molecule can be described as that of cycloh ...

(18-methylestrane) subgroup of the

family of progestins. Etonogestrel is the C3

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double b ...

derivative of desogestrel and the C11 methylene derivative of

and is also known as 3-ketodesogestrel and as 11-methylenelevonorgestrel.

History

The possibility of the subdermal contraceptive implant began when silicone was discovered in the 1940s and found to be bio-compatible with the human body. In 1964, Folkman and Long published the first study demonstrating that such a rod could be used to deliver drugs. In 1966 Dziuk and Cook published a study that looked at release rates and suggested that the rods could be well suited for contraception. After a study that used implants with progestogens for contraception, the Population Council developed and patented Norplant and

Jadelle Levonorgestrel-releasing implant, sold under the brand name Jadelle among others, are devices that release levonorgestrel for birth control. It is one of the most effective forms of birth control with a one-year failure rate around 0.05%. The dev ...

. Norplant has six rods and is considered a first-generation implant. Jadelle (Norplant II), a two-rod implant, and other single rod implants that followed, were developed because of complications resulting from Norplant's 6-rod system. The Jadelle system contains two silicone rods mixed with levonorgestrel. In 1990 De Nijs patented a co-axial extrusion technique of ethylene vinylacetate copolymers and 3-keto-desogestrel (etonogestrel) for the preparation of long-acting contraceptive devices, such as Implanon, Nexplanon and Nuvaring. The single rods were less visible under the skin and used etonogestrel as opposed to levonorgestrel in the hopes that it would reduce side effects. Desogestrel (3-deketoetonogestrel), a

of etonogestrel, was introduced for medical use in 1981. Norplant was used internationally beginning in 1983 and was marketed in the United States and the United Kingdom in 1993. There were many complications associated with Norplant removal in the United States and it was taken off the market in 2002. Although Jadelle was approved by the FDA, it has never been marketed in the United States, but it is widely used in Africa and Asia. Etonogestrel itself was first introduced as Implanon in Indonesia in 1998, was marketed 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 Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...

shortly thereafter, and approved for use in the United States in 2006. Nexplanon was developed to eliminate the problem of non-insertion and localization of Implanon by changing the inserter device and making the rod radiopaque. As of January 2012, Implanon is no longer being marketed and Nexplanon is the only available single-rod implant.

Society and culture

Generic names

''Etonogestrel'' is the generic name of the drug and its , , and . It is also known by its developmental code name ''ORG-3236''.

Brand names

Etonogestrel is marketed under the brand names Circlet, Implanon, Nexplanon, and NuvaRing.

Availability

Etonogestrel is available widely throughout the world, including in the

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...

, the

Ireland Ireland ( ; ga, Éire ; Ulster-Scots: ) is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the s ...

, elsewhere throughout

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...

Latin America Latin America or * french: Amérique Latine, link=no * ht, Amerik Latin, link=no * pt, América Latina, link=no, name=a, sometimes referred to as LatAm is a large cultural region in the Americas where Romance languages — languages derived ...

South South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...

, East, and

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainland ...

, and elsewhere in the world.

Research

An etonogestrel-releasing

intrauterine device An intrauterine device (IUD), also known as intrauterine contraceptive device (IUCD or ICD) or coil, is a small, often T-shaped birth control device that is inserted into the uterus to prevent pregnancy. IUDs are one form of long-acting revers ...

was under development for use as a form of birth control for women but development was discontinued in 2015. Etonogestrel has been studied for use as a potential male contraceptive.

References

External links

Etonogestrel implant - AdisInsight

Ethinylestradiol/etonogestrel vaginal ring - AdisInsight
{{portal bar, Medicine 5α-Reductase inhibitors Hormonal contraception Human drug metabolites Progestogens Articles containing video clips World Health Organization essential medicines Wikipedia medicine articles ready to translate Ethynyl compounds Dienes Enones Estranes Vinylidene compounds