Alfatradiol
Encyclopedia
Alfatradiol is a 5α-reductase inhibitor used topical
ly for the treatment of androgenic alopecia (hair loss) in men and women.
ic solution for topical application on the scalp
. Similarly to other drugs against alopecia, topical or oral
, it has to be applied continuously to prevent further hair loss. Regrowth of hair that was already lost is only possible to a limited extent. In general, advanced alopecia does not respond well to medical treatment, which is thought to be a consequence of the hair roots being lost.
A study in 103 women comparing alfatradiol to minoxidil
, another topical hair loss treatment, found the latter to be more effective. In contrast to minoxidil, alfatradiol did not result in an increase of hair density or thickness, but only in slowing down or stabilization of hair loss in this study.
or lactation
, or in patients under 18 years of age. It should not be used under these circumstances.
in the solvent. The solution can stimulate sebum production.
(17β-estradiol), the predominant sex hormone in females, only by the stereochemistry
of the carbon
atom 17. Contrary to estradiol, alfatradiol has no estrogen
activity, but intead acts as an inhibitor of the enzyme 5α-reductase which is responsible for the activation of testosterone
to dihydrotestosterone
, which plays a role in regulating hair growth.
Topical
In medicine, a topical medication is applied to body surfaces such as the skin or mucous membranes such as the vagina, anus, throat, eyes and ears.Many topical medications are epicutaneous, meaning that they are applied directly to the skin...
ly for the treatment of androgenic alopecia (hair loss) in men and women.
Uses
Alfatradiol is used in form of an ethanolEthanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
ic solution for topical application on the scalp
Scalp
The scalp is the anatomical area bordered by the face anteriorly and the neck to the sides and posteriorly.-Layers:It is usually described as having five layers, which can conveniently be remembered as a mnemonic:...
. Similarly to other drugs against alopecia, topical or oral
Oral administration
Oral administration is a route of administration where a substance is taken through the mouth.-Terminology:Per os is an adverbial phrase meaning literally from Latin "by mouth" or "by way of the mouth." The expression is used in medicine to describe a treatment that is taken orally. The...
, it has to be applied continuously to prevent further hair loss. Regrowth of hair that was already lost is only possible to a limited extent. In general, advanced alopecia does not respond well to medical treatment, which is thought to be a consequence of the hair roots being lost.
A study in 103 women comparing alfatradiol to minoxidil
Minoxidil
Minoxidil is an antihypertensive vasodilator medication which also slows or stops hair loss and promotes hair regrowth. Now off-patent, it is available over-the-counter for the treatment of androgenic alopecia. Minoxidil must be used indefinitely for continued support of existing hair follicles and...
, another topical hair loss treatment, found the latter to be more effective. In contrast to minoxidil, alfatradiol did not result in an increase of hair density or thickness, but only in slowing down or stabilization of hair loss in this study.
Contraindications
Nothing is known about the use of alfatradiol during pregnancyPregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
or lactation
Lactation
Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process occurs in all female mammals, however it predates mammals. In humans the process of feeding milk is called breastfeeding or nursing...
, or in patients under 18 years of age. It should not be used under these circumstances.
Adverse effects
Local burning or itching is not an effect of alfatradiol but of the ethanolEthanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
in the solvent. The solution can stimulate sebum production.
Chemistry and pharmacology
Alfatradiol (17α-estradiol) is distinguished from estradiolEstradiol
Estradiol is a sex hormone. Estradiol is abbreviated E2 as it has 2 hydroxyl groups in its molecular structure. Estrone has 1 and estriol has 3 . Estradiol is about 10 times as potent as estrone and about 80 times as potent as estriol in its estrogenic effect...
(17β-estradiol), the predominant sex hormone in females, only by the stereochemistry
Stereochemistry
Stereochemistry, a subdiscipline of chemistry, involves the study of the relative spatial arrangement of atoms within molecules. An important branch of stereochemistry is the study of chiral molecules....
of the carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
atom 17. Contrary to estradiol, alfatradiol has no estrogen
Estrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...
activity, but intead acts as an inhibitor of the enzyme 5α-reductase which is responsible for the activation of testosterone
Testosterone
Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands...
to dihydrotestosterone
Dihydrotestosterone
Dihydrotestosterone is an androgen or male sex hormone. The enzyme 5α-reductase synthesises DHT in the prostate, testes, hair follicles, and adrenal glands...
, which plays a role in regulating hair growth.
See also
- Alfatradiol/dexamethasoneAlfatradiol/dexamethasoneThe drug combination alfatradiol/dexamethasone is used topically for the treatment of mild to moderate androgenic alopecia in younger women....
(Ell-Cranell dexa) - Estradiol 17alpha-dehydrogenaseEstradiol 17alpha-dehydrogenaseIn enzymology, an estradiol 17alpha-dehydrogenase is an enzyme that catalyzes the chemical reactionThe three substrates of this enzyme are estradiol-17alpha, NAD+, and NADP+, whereas its four products are estrone, NADH, NADPH, and H+....