Allylestrenol

Allylestrenol (INN) (brand names Gestanon, Gestanin, Orageston, Turinal, Gestin, others), or allyloestrenol (BAN), also known as 17α-allylestr-4-en-17β-ol or as 3-deketo-17α-allyl-19-nortestosterone, is a steroidal progestin of the 19-nortestosterone and 17α-allyltestosterone groups that is used to prevent threatened miscarriage, recurrent pregnancy loss and premature labor. It has also been studied as a treatment for benign prostatic hyperplasia in men, with encouraging results. Allylestrenol is marketed widely throughout Europe, including in the United Kingdom (no longer available), Russia, and many other European countries, and is also available in Japan, Hong Kong, India, Bangladesh, Indonesia, and much of Southeast Asia, though notably not in the United States or Canada.

Although it is less potent as a progestogen relative to many other 19-nortestosterone derivatives, allylestrenol is said to be virtually devoid of androgenic, estrogenic, or glucocorticoid activity, and hence, unlike virtually all other 19-nortestosterone derivatives, appears to be a pure progestogen with similar effects to those of progesterone. As it is lacking in a keto group at the C3 position, allylestrenol is thought to be a prodrug into 17α-allyl-19-nortestosterone (or 17α-allylnandrolone). It was patented in 1958 and has been marketed since 1961.