Medrogestone, sold under the brand name Colprone among others, is a progestin medication which has been used in menopausal hormone therapy and in the treatment of gynecological disorders.

[17] Intrahepatic cholestasis of pregnancy (acute or in history), vaginal bleeding of unknown origin, and severe diseases of the liver such as tumors are absolute contraindications for medrogestone, as are thrombotic events such as thrombophlebitis or stroke.

[19] It is not known whether medrogestone passes into breast milk, but it is to be expected given its lipophilicity and studies with structurally related progestins.

Chronic toxicity has been examined in animals, but nothing but the typical adverse effects of progestogens, and reduction of prostatic weight in rhesus monkeys, have been found.

[18] Enzyme inducers such as barbiturates, phenylbutazone, phenytoin, ampicillin or tetracyclines are expected to reduce plasma concentrations of medrogestone, but no systematic research has been done.

[9] Accordingly, no evidence of androgenic or glucocorticoid activity, including effects on the estrogen-induced increase in triglycerides and HDL cholesterol and adrenal suppression, were observed in clinical studies.

[2][21] However, in a very high-dosage (100 mg/day for 6 months) study of medrogestone for benign prostatic hyperplasia, a hyperglycemic effect and changes in plasma cortisol levels were observed and considered likely to be secondary to glucocorticoid activity, and decreased sodium levels were also observed and attributed to antimineralocorticoid activity.

[22][23][24] In addition, similarly to progesterone, medrogestone can inhibit 5α-reductase in vitro in microsomal preparations of skin and prostate.

This compound, which may well owe this property to the inhibition of metabolism in a manner analogous to synthetic androgens and estrogens, is not sufficiently potent in its own right to constitute a useful drug.

Reduction of the conjugated 16,17 double bond of 6-methyl-16-dehydropregnenolone acetate by means of lithium in liquid ammonia leads initially to the 17 enolate ion; this is alkylated in situ with methyl iodide.

In an interesting modification on the usual scheme, (3) is treated with aluminum isopropoxide and a ketone (Oppenauer conditions) as well as chloranil in a single reaction; the 4,6-diene, (medrogesterone), is obtained directly from this step.

[11][13][7] Medrogestone has been marketed in the United States[9] and Canada and widely throughout Europe, as well as in Argentina, Hong Kong, and other countries.