Title: Finasteride
CAS Registry Number: 98319-26-7
CAS Name: (5a,17b)-N-(1,1-Dimethylethyl)-3-oxo-4-azaandrost-1-ene-17-carboxamide
Additional Names: 17b-(N-tert-butylcarbamoyl)-4-aza-5a-androst-1-en-3-one
Manufacturers' Codes: MK-906
Trademarks: Chibro-Proscar (Chibret); Finastid (Neopharmed); Propecia (Merck & Co.); Proscar (Merck & Co.); Prostide (Sigma-Tau)
Molecular Formula: C23H36N2O2
Molecular Weight: 372.54
Percent Composition: C 74.15%, H 9.74%, N 7.52%, O 8.59%
Literature References: Inhibitor of 5a-reductase, the enzyme which converts testosterone to the more potent androgen, 5a-dihydrotestosterone. Prepn: G. H. Rasmusson, G. F. Reynolds, EP 155096; eidem, US 4760071 (1985, 1988 both to Merck & Co.); G. H. Rasmusson et al., J. Med. Chem. 29, 2298 (1986); A. Bhattacharya et al., J. Am. Chem. Soc. 110, 3318 (1988). HPLC determn in plasma and urine: J. R. Carlin et al., J. Chromatogr. 427, 79 (1988). Review of pharmacology and clinical uses: S. L. Sudduth, M. J. Koronkowski, Pharmacotherapy 13, 309-329 (1993). Clinical trials in benign prostatic hyperplasia: J. L. Tenover et al., Clin. Ther. 19, 243 (1997); J. D. McConnell et al., N. Engl. J. Med. 338, 557 (1998); in male pattern hair loss: K. D. Kaufman et al., J. Am. Acad. Dermatol. 39, 578 (1998).
Properties: White to off-white crystalline solid, mp ~257° (dried to anhydrous under N2). Also reported as mp 252-254° (Rasmusson, 1988). [a]405 -59° (c = 1 in methanol). Freely sol in chloroform, DMSO, ethanol, methanol, n-propanol; sparingly sol in propylene glycol, polyethylene glycol 400; very slightly sol in 0.1N HCl, 0.1N NaOH, water.
Melting point: mp ~257° (dried to anhydrous under N2); mp 252-254° (Rasmusson, 1988)
Optical Rotation: [a]405 -59° (c = 1 in methanol)
Therap-Cat: Treatment of benign prostatic hypertrophy. Antialopecia agent.
Keywords: Antialopecia Agent; Antiprostatic Hypertrophy; 5a-Reductase Inhibitor.
Fingolimod Fipexide Firefly Luciferin Firocoxib Fisetin

Systematic (IUPAC) name
Clinical data
Trade names Propecia, Proscar
AHFS/ monograph
MedlinePlus a698016
Pregnancy cat. X (will cause birth defects in a fetus)
Legal status POM (UK) -only (US)
Routes Oral
Pharmacokinetic data
Bioavailability 63%
Metabolism Hepatic
Half-life Elderly: 8 hours
Adults: 6 hours
Excretion Feces (57%) and urine (39%) as metabolites
CAS number 98319-26-7 YesY
ATC code G04CB01 D11AX10
PubChem CID 57363
DrugBank DB01216
ChemSpider 51714 YesY
KEGG D00321 YesY
Chemical data
Formula C23H36N2O2 
Mol. mass 372.549 g/mol
 YesY (what is this?)  (verify)

Finasteride (brand names Proscar and Propecia by Merck, among other generic names) is a synthetic drug for the treatment of benign prostatic hyperplasia (BPH) and male pattern baldness (MPB). It is a type II 5α-reductase inhibitor. 5α-reductase is an enzyme that converts testosterone to dihydrotestosterone (DHT).