Pregnenolone, sold under the brand name Enelone among others, is a

medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field and ...

and supplement as well as a

naturally occurring A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical sy ...

and endogenous steroid. It is described as a neurosteroid and anti-inflammatory drug and was used in the treatment of

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are invol ...

and

soft-tissue Soft tissue is all the tissue in the body that is not hardened by the processes of ossification or calcification such as bones and teeth. Soft tissue connects, surrounds or supports internal organs and bones, and includes muscle, tendons, ligam ...

rheumatism in the 1950s but is no longer used today. Pregnenolone can be taken

by mouth Oral administration is a route of administration where a substance is taken through the mouth. Per os abbreviated to P.O. is sometimes used as a direction for medication to be taken orally. Many medications are taken orally because they are i ...

, as a

topical medication A topical medication is a medication that is applied to a particular place on or in the body. Most often topical medication means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of classes ...

, or by injection into muscle. Pregnenolone is promoted online with false claims that it can treat a variety of health conditions including

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

, arthritis and multiple sclerosis.

Medical uses

Pregnenolone was approved for use as a pharmaceutical medication in the treatment of

and

rheumatism in the 1950s. It is no longer used today.

Available forms

Pregnenolone acetate Pregnenolone acetate (brand names Antofin, Previsone, Pregno-Pan), also known as pregn-5-en-3β-ol-20-one 3β-acetate, is a synthetic pregnane steroid and an ester of pregnenolone which is described as a glucocorticoid and as a skin-conditionin ...

was available as Enelone in the form of 100 mg

oral The word oral may refer to: Relating to the mouth * Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid **Oral administration of medicines ** Oral examination (also known as an oral exam or or ...

tablets and as a 100 mg/mL

crystalline A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

aqueous suspension In chemistry, a suspension is a Mixture#Homogeneous and heterogeneous mixtures, heterogeneous mixture of a fluid that contains solid particles sufficiently large for sedimentation. The particles may be macroscopic, visible to the naked eye, usual ...

in 10 mL

vial A vial (also known as a phial or flacon) is a small glass or plastic vessel or bottle, often used to store medication as liquids, powders or capsules. They can also be used as scientific sample vessels; for instance, in autosampler devices i ...

Pharmacology

Pregnenolone is a neurosteroid. It is a

negative allosteric modulator In pharmacology and biochemistry, allosteric modulators are a group of substances that bind to a receptor to change that receptor's response to stimulus. Some of them, like benzodiazepines, are drugs. The site that an allosteric modulator binds t ...

of the CB₁ receptor, a

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...

of the

microtubule-associated protein 2 Microtubule-associated protein 2 is a protein in humans that is encoded by the ''MAP2'' gene. Function This gene encodes a protein that belongs to the microtubule-associated protein family. The proteins of this family were originally isolated s ...

(MAP2), and an agonist of the

pregnane X receptor In the field of molecular biology, the pregnane X receptor (PXR), also known as the steroid and xenobiotic sensing nuclear receptor (SXR) or nuclear receptor subfamily 1, group I, member 2 (NR1I2) is a protein that in humans is encoded by the ' ...

. Pregnenolone has no progestogenic, corticosteroid,

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 ...

ic,

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

ic, or

antiandrogen Antiandrogens, also known as androgen antagonists or testosterone blockers, are a class of drugs that prevent androgens like testosterone and dihydrotestosterone (DHT) from mediating their biological effects in the body. They act by blocking the ...

ic activity. In addition to its own activities, pregnenolone is a

precursor Precursor or Precursors may refer to: * Precursor (religion), a forerunner, predecessor ** The Precursor, John the Baptist Science and technology * Precursor (bird), a hypothesized genus of fossil birds that was composed of fossilized parts of u ...

for other neurosteroids such as

pregnenolone sulfate Pregnenolone sulfate (PS, PREGS) is an endogenous excitatory neurosteroid that is synthesized from pregnenolone. It is known to have cognitive and memory-enhancing, antidepressant, anxiogenic, and proconvulsant effects. Biological activity Pr ...

, allopregnanolone, and pregnanolone and for

steroid hormone A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into two classes: corticosteroids (typically made in the adrenal cortex, hence ''cortico-'') and sex steroids (typically made in the gonads or placenta). Withi ...

s. Pregnenolone has low

bioavailability In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. Ho ...

and is subject to high

metabolism 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 c ...

Oral administration Oral administration is a route of administration where a substance is taken through the mouth. Per os abbreviated to P.O. is sometimes used as a direction for medication to be taken orally. Many medications are taken orally because they are ...

of 50 or 100 mg pregnenolone has been found to have minimal or negligible effect on

urinary The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, co ...

levels of

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 ...

and testosterone metabolites, including of

androsterone Androsterone, or 3α-hydroxy-5α-androstan-17-one, is an endogenous steroid hormone, neurosteroid, and putative pheromone. It is a weak androgen with a potency that is approximately 1/7 that of testosterone. Androsterone is a metabolite of test ...

etiocholanolone Etiocholanolone, also known as 5β-androsterone, as well as 3α-hydroxy-5β-androstan-17-one or etiocholan-3α-ol-17-one, is an etiocholane (5β-androstane) steroid as well as an endogenous 17-ketosteroid that is produced from the metabolism of ...

, 5β-androstanediol,

androstadienol Androstadienol, or androsta-5,16-dien-3β-ol, is a 16-androstene class endogenous steroid, pheromone, and chemical intermediate to several other pheromones that is found in the sweat of both men and women. Androstadienol and androstadienone ...

, and

androstenol Androstenol, also known as 5α-androst-16-en-3α-ol (shortened to 3α,5α-androstenol or 3α-androstenol), is a 16-androstene class steroidal pheromone and neurosteroid in humans and other mammals, notably pigs. It possesses a characteristic musk ...

(and/or their conjugates), and this suggests that only a small amount of pregnenolone is converted into testosterone. This is in accordance with findings on the conversion of

DHEA Dehydroepiandrosterone (DHEA), also known as androstenolone, is an endogenous steroid hormone precursor. It is one of the most abundant circulating steroids in humans. DHEA is produced in the adrenal glands, the gonads, and the brain. It functio ...

into testosterone, in which only 1.5% of an oral dose of DHEA was found to be converted into testosterone. In contrast to the

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 Pharmacology ...

s, 50 or 100 mg oral pregnenolone has been found to significantly and in fact "strongly" increase urinary levels of the progesterone metabolites pregnanediol and pregnanolone (and/or their conjugates), whereas pregnanetriol was unaffected. Unlike the case of oral administration,

transdermal administration Transdermal is a route of administration wherein active ingredients are delivered across the skin for systemic distribution. Examples include transdermal patches used for medicine delivery. The drug is administered in the form of a patch or ointme ...

of 30 mg/day pregnenolone cream has not been found to affect urinary levels of metabolites of any other steroids, including of progesterone.

Intranasal administration Nasal administration, popularly known as snorting, is a route of administration in which drugs are insufflated through the nose. It can be a form of either topical administration or systemic administration, as the drugs thus locally delivere ...

of pregnenolone was found to have low bioavailability of around 23%. Sripada et al. reported that oral pregnenolone is preferentially metabolized into the neurosteroid allopregnanolone rather than into other steroids such as DHEA or cortisol. In further research by their group, a single 400 mg dose of oral pregnenolone at 3 hours post-administration was found to result in a 3-fold elevation in serum levels of pregnenolone and a 7-fold increase in allopregnanolone levels. Pregnanolone levels increased by approximately 60% while DHEA levels decreased non-significantly by approximately 5% and cortisol levels were not affected. Another study found that allopregnanolone levels were increased by 3-fold at 2 hours post-administration following a single 400 mg oral dose of pregnenolone. In addition to allopregnanolone, pregnenolone acts as a prodrug of pregnenolone sulfate. However, pregnenolone sulfate does not cross the blood–brain barrier.

Chemistry

Pregnenolone, also known as 5-pregnenolone or as pregn-5-en-3β-ol-20-one, is a

pregnane Pregnane, also known as 17β-ethylandrostane or as 10β,13β-dimethyl-17β-ethylgonane, is a C21 steroid and, indirectly, a parent of progesterone. It is a parent hydrocarbon for two series of steroids stemming from 5α-pregnane (originally allop ...

steroid 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. ...

cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...

. Related steroids include

, 3β-dihydroprogesterone (4-pregnenolone), progesterone, allopregnanolone, and pregnanolone.

Derivatives

A few synthetic

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides a ...

s of pregnenolone exist. These include

pregnenolone acetate Pregnenolone acetate (brand names Antofin, Previsone, Pregno-Pan), also known as pregn-5-en-3β-ol-20-one 3β-acetate, is a synthetic pregnane steroid and an ester of pregnenolone which is described as a glucocorticoid and as a skin-conditionin ...

(Antofin, Previsone, Pregno-Pan) and

pregnenolone succinate Pregnenolone succinate (; brand names Panzalone, Formula 405; also known as pregnenolone hemisuccinate or pregn-5-en-3β-ol-20-one 3β-(hydrogen succinate)) is a synthetic pregnane steroid and an ester of pregnenolone which is described as a glu ...

(Panzalone, Formula 405).

Prebediolone acetate Prebediolone acetate (brand names Acetoxanon, Acetoxanone, Acetoxy-Prenolon, Artisone, Artivis, Pregnartrone, Sterosone), also known as 21-hydroxypregnenolone 21-acetate or 21-acetoxypregnenolone (A.O.P.), as well as 3β,21-dihydroxypregn-5-en-20 ...

(Acetoxanon, Acetoxy-Prenolon, Artisone, Artivis, Pregnartrone, Sterosone), the 21- acetate

of 21-hydroxypregnenolone, also exists. These esters are all described as

glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every verteb ...

s similarly to pregnenolone. The 3β- methyl

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be ...

of pregnenolone,

3β-methoxypregnenolone 3β-Methoxypregnenolone (developmental code name MAP-4343), or pregnenolone 3β-methyl ether, also known as 3β-methoxypregn-5-en-20-one, is a synthetic neuroactive steroid and derivative of pregnenolone. It interacts with microtubule-associate ...

(MAP-4343), retains similar activity to pregnenolone in regard to interaction with MAP2, and is under development for potential clinical use for indications such as the treatment of

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

and

spinal cord injury A spinal cord injury (SCI) is damage to the spinal cord that causes temporary or permanent changes in its function. Symptoms may include loss of muscle function, sensation, or autonomic function in the parts of the body served by the spinal cor ...

and

depressive disorder A mood disorder, also known as an affective disorder, is any of a group of conditions of mental and behavioral disorder where a disturbance in the person's mood is the main underlying feature. The classification is in the ''Diagnostic and Stat ...

History

Pregnenolone was first synthesized by

Adolf Butenandt Adolf Friedrich Johann Butenandt (; 24 March 1903 – 18 January 1995) was a German biochemist. He was awarded the Nobel Prize in Chemistry in 1939 for his "work on sex hormones." He initially rejected the award in accordance with government po ...

and colleagues in 1934. It was first used in medicine, as an

anti-inflammatory Anti-inflammatory is the property of a substance or treatment that reduces inflammation or swelling. Anti-inflammatory drugs, also called anti-inflammatories, make up about half of analgesics. These drugs remedy pain by reducing inflammation as o ...

medication, in the 1940s.

Society and culture

Generic names

''Pregnenolone'' is the generic name of the drug and its , , , and .

Brand names

Pregnenolone has been marketed in the past under a variety of brand names including Arthenolone, Bina-Skin, Enelone, Natolone, Pregnetan, Pregneton, Pregnolon, Prenolon, Prenolone, Regnosone, Sharmone, and Skinostelon.

Availability

Pregnenolone is no longer marketed as a medication, but remains available as a supplement.

Alternative medicine

Pregnenolone has been promoted online with claims it can treat a variety of diseases including multiple sclerosis, arthritis, and

, but such claims are not backed by evidence.

Research

pregnenolone is being researched for possible therapeutic applications, but its poor

makes its prospects for usefulness low. Pregnenolone is available as an

over-the-counter Over-the-counter (OTC) drugs are medicines sold directly to a consumer without a requirement for a prescription from a healthcare professional, as opposed to prescription drugs, which may be supplied only to consumers possessing a valid prescr ...

supplement, for instance 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 primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

References

{{Navboxes , title =

Pharmacodynamics Pharmacodynamics (PD) is the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs). The effects can include those manifested within animals (including humans), microorganisms, or combinations of organisms ...

, titlestyle = background:#ccccff , list1 = {{Cannabinoid receptor modulators {{Glycine receptor modulators {{Sigma receptor modulators {{Xenobiotic-sensing receptor modulators Abandoned drugs Anti-inflammatory agents CB1 receptor antagonists Glycine receptor agonists Ketones Neurosteroids Pregnane X receptor agonists Pregnanes Prodrugs Secondary alcohols Sigma agonists