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Not to be confused with Medroxyprogesterone acetate.
Systematic (IUPAC) name
Clinical data
Pregnancy cat.
  • X
Legal status
  • Prescription only
Routes Oral
Pharmacokinetic data
Bioavailability 100%
Metabolism Hydroxylation and glucuronidation
Half-life 4 to 5 hours
Excretion Renal and fecal, as metabolites
CAS number 977-79-7
ATC code G03DB03
G03FB07 (with estrogen)
PubChem CID 9949848
ChemSpider 8125459
UNII 077DN93G5B YesY
KEGG D04885
Chemical data
Formula C23H32O2 
Mol. mass 340.5 g/mol

Medrogestone (INN; trade names Colpro(ne) by Wyeth and Prothil by Solvay) is a progestin, a synthetic drug with similar effects as progesterone,[1] a hormone involved in the menstrual cycle and pregnancy. As of 2010, it is no longer available in Germany or Austria.[2]


In the past, medrogestone was used in the treatment of endometrial cancer and in some regimens for breast cancer, and, in men, for benign prostatic hyperplasia. It still finds use in the treatment of amenorrhea[3] and as the progestin component in certain forms of menopausal hormone replacement therapy.[4]


Intrahepatic cholestasis of pregnancy (acute or in history), vaginal bleeding of unknown origin, and severe diseases of the liver such as tumours are absolute contraindications for medrogestone. Relative contraindications include a history of jaundice or itching in pregnancy or gestational pemphigoid.[5]

Pregnancy and lactation[edit]

Medrogestone is contraindicated during pregnancy because progestogens are associated with risks for the foetus in animals and humans.[1] Studies in pregnant rabbits have shown skeletal deformations under 3 mg medrogestone per kilogram body weight but not under 1 mg/kg.[5] Typical therapeutic doses are between 0.1 and 0.25 mg/kg.

It is not known whether medrogestone passes into breast milk, but it is to be expected given its lipophilicity and studies with chemically related progestins.[1]

Adverse effects[edit]

Medrogestone seldom produces adverse effects, all of which are typical of progestogens. They include lack of appetite, nausea, headache, dizziness, and depression.[5]


The acute toxicity of the drug is low. Overdose causes only harmless side-effects such as nausea and vaginal bleeding.[1] The LD50 has been found to range between 500 mg/kg in dogs and over 3000 mg/kg in rats. 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. Accidental intake of the drug, including in children, is not dangerous.[5]

Chemical properties[edit]

Medrogestone is a steroid. More specifically, it is a derivative of pregna-4,6-diene structurally related to the progestin chlormadinone acetate and the antiandrogen cyproterone acetate. As is frequently found in other synthetic steroid hormones, medrogestone possesses a lipophilic group at position 6. However in contrast to chlormadinone acetate and cyproterone acetate or to fluocinolone that contain a chlorine or fluorine respectively at position 6, medrogestone contains a methyl substituent at this position. The methyl in position 17 is unusual for a steroid, as many such drugs carry an oxygen atom in that position.



The drug is absorbed quickly and completely from the gut and reaches peak plasma concentrations after about one to four hours. Unlike many other steroids it binds neither to transcortin (corticosteroid-binding globulin, CBG, which binds progesterone[6]) nor to sex hormone-binding globulin (SHBG), but to albumin.[5] Medrogestone itself cannot be excreted. The substance is hydroxylised and glucuronidised in the liver, and the resulting metabolites are eliminated via urine and faeces.[5]


The profile of medrogestone is similar to the natural hormone progesterone. It has pronounced progestogenic effects and opposes the proliferative effects of estrogen in the utereus, but lacks anabolic, androgenic, estrogenic and corticoid activity.[5] In extremely high doses it is an androgen antagonist (in 2500-fold therapeutic doses[5]) as well as an antigonadotropin.[1]


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.[1]


  1. ^ a b c d e f "Fachinformation zu Colpro" [Colpro summary of product characteristics] (in German). Open Drug Database. November 1997. Retrieved 15 August 2010. 
  2. ^ Jasek, W, ed. (2006). Austria-Codex (in German) 1 (2006/2007 ed.). Vienna: Österreichischer Apothekerverlag. p. 1696. ISBN 3-85200-176-5. 
  3. ^ Medrogestone at the US National Library of Medicine Medical Subject Headings (MeSH)
  4. ^ Sweetman, Sean C., ed. (2009). "Sex hormones and their modulators". Martindale: the complete drug reference (36th ed.). London: Pharmaceutical Press. p. 2113. ISBN 978-0-85369-840-1. 
  5. ^ a b c d e f g h Daunderer, Max (August 2001). "Medrogeston". Klinische Toxikologie (in German) (152 ed.). pp. 31–33. Retrieved 15 August 2010. 
  6. ^ Loose DS, Stancel GM (2006). "57. Estrogens and Progestins". In Laurence Brunton, John Lazo, Keith Parker (eds.). Goodman & Gilman's The Pharmacological Basis of Therapeutics (11th ed.). New York: McGraw-Hill. pp. 1541–73. ISBN 978-0-07-142280-2.