Applications for patents of 5-alpha reductase inhibitors began in the mid-1970s, after an influential 1974 study by Imperato-McGinley et al., as described in ‘How was finasteride invented? ‘
From 1980 through the mid-1990s, most patents were filed by Merck and SmithKline Beckham, a precursor of GlaxoSmithKline. Merck’s application for Proscar (finasteride 5 mg) was approved by FDA in 1992. Its application for Propecia (finasteride 1 mg) was approved in December 1997. GlaxoSmithKline’s application for Avodart (dutasteride 0.5 mg) was approved in 2001.
Merck’s key patent for Propecia appears to be Patent No. 5,571,817, granted Nov 5, 1996: “Methods of treating androgenic alopecia with finasteride… “
This is a selection of patents which appear to be most relevant to drug development. More may be found via USPTO Public Search .
Patent # Date Title Assignee 3,917,829 Nov 4, 1975 Novel methods of inhibiting the activity of testosterone 5.alpha.-reductase Research Corporation 4,088,760 May 9, 1978 Testosterone 5.alpha.-reductase inhibitors Richardson-Merrell 4,191,759 Mar 4, 1980 N-substituted-17.beta.-carbamoylandrost-4-en-3-one 5.alpha. reductase inhibitors Merck Sep 2, 1980 Preparation of 4-aza-17-substituted-5.alpha.-androstan-3-ones useful as 5.alpha.-reductase inhibitors Merck 4,317,817 Mar 2, 1982 Novel steroid 5.alpha.-reductase inhibitors Richardson-Merrell 4,361,578 Nov 30, 1982 D-Homosteroids Alig, Leo et al. (Switzerland & Germany) 4,377,584 Mar 22, 1983 4-Aza-17.beta.-substituted-5.alpha.-androstan-3-one-reductase inhibitors Merck 4,732,897 Mar 22, 1988 Steroidic 5.alpha.-reductase inhibitors Farmitalia; Consiglio Nazonale Delle Ricerche 4,760,071 Jul 26, 1988 17.beta.-N-monosubstituted carbamoyl-4-aza-5.alpha.-androst-1-en-3-ones which are active as testosterone 5.alpha.-reductase inhibitors Merck 4,845,104 Jul 4, 1989 Oxidized analogs of 17.beta.-N-monosubstituted-carbamoyl-4-aza-5-.alpha.-androstan-3-ones Merck 4,859,681 Aug 22, 1989 17.alpha.-Acyl-4-aza-5a-androst-1-en-3-ones as 5 alpha-reductase inhibitors Merck 4,882,319 Nov 21, 1989 Phosphonic acid substituted aromatic steroids as inhibitors of steroid 5-.alpha.-reductase SmithKline Beckman 4,888,336 Dec 19, 1989 Steroid 5-alpha-reductase inhibitors SmithKline Beckman 4,910,226 Mar 20, 1990 Steroid 5-alpha-reductase inhibitors SmithKline Beckman 4,937,237 Jun 26, 1990 Phosphinic acid substituted aromatic steroids as inhibitors of steroid 5-60 -reductase SmithKline Beckman 5,017,568 May 21, 1991 Steriod [sic] 5-alpha-reductase inhibitors SmithKline Beecham 5,061,802 Oct 29, 1991 17.beta.-aminobenzoyl-4-aza-5.alpha.-androst-1-en-3-ones as benign prostatic hypertrophy agents Glaxo 5,098,908 Mar 24, 1992 17.beta.-hydroxybenzoyl-4-aza-5.alpha.-androst-1-en-3-ones as testosterone reductase inhibitors Merck 5,302,589 Apr 12, 1994 Heterocyclic inhibitors of 5-.alpha.-testosterone reductase Glaxo 5,571,817 Nov 5, 1996 Methods of treating androgenic alopecia with finasteride [17.beta.-N-mono-substituted-carbamoyl-4-aza-5-.alpha.-androst-1-en-ones] Merck
