Fertilysin (WIN 18446) is an experimental drug that was studied as a

male contraceptive Male contraceptives, also known as male birth control, are methods of preventing pregnancy by interrupting the function of sperm. The main forms of male Birth control, contraception available today are condoms, vasectomy, and Coitus interruptus, w ...

, but was never marketed. It interferes with testicular production of

retinoic acid Retinoic acid (simplified nomenclature for all-''trans''-retinoic acid) is a metabolite of vitamin A1 (all-''trans''-retinol) that is required for embryonic development, male fertility, regulation of bone growth and immune function. All-''trans ...

, which is necessary for

spermatogenesis Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testicle. This process starts with the Mitosis, mitotic division of the stem cells located close to the basement membrane of ...

. In studies in male animals including rodents, wolves, cats, and shrews, fertilysin was found to be a safe, effective, and reversible oral contraceptive. However, the side effects observed in human clinical trials preclude its use in men. Fertilysin was originally studied in the 1950s for its potential amebicidal effects. When the anti-spermatogenesis effects were observed in animal studies, the focus of the research turned towards its potential use as a contraceptive. Fertilysin is an inhibitor of aldehyde dehydrogenase 1a2, a member of the

aldehyde dehydrogenase Aldehyde dehydrogenases () are a group of enzymes that catalyse the oxidation of aldehydes. They convert aldehydes (R–C(=O)) to carboxylic acids (R–C(=O)). The oxygen comes from a water molecule. To date, nineteen ALDH genes have ...

family of enzymes. Inhibition of this enzyme blocks the production of retinoic acid which prevents the production of sperm. Because aldehyde dehydrogenases are also involved in the metabolism of ethanol, fertilysin has side effects similar to the action of

disulfiram Disulfiram is a medication used to support the treatment of chronic alcoholism by producing an acute sensitivity to ethanol (drinking alcohol). Disulfiram works by Enzyme inhibition, inhibiting the enzyme aldehyde dehydrogenase (specifically ALD ...

(Antabuse). Fertilysin may also have teratogenic effects.

References

{{reflist Abandoned drugs Amides Dichloromethyl compounds Contraception for males