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FinasterideFinasteride

StructureStructure

Finasteride belongs to the subclass of steroids called azasteroids. All steroids contain a core structure called gonane, a structure composed of 3 cyclohexane rings and 1 cyclopentane ring "fused" together. The function and naming of the gonane are determined the addition of functional groups, the spatial orientation of carbon 5, and by the substitution of carbon atoms in the ring structures with different atoms.

In the case of Finasteride, two methyl groups have

MechanismMechanism

Finasteride is a 5-alpha reductase inhibitor. There are two isoforms of the 5alpha-reductase enzyme, type I and II, and while the drug has a higher affinity for the type II enzyme, it also inhibits the function of the type I. (.....) Typically 5 alpha-redcutase turns testosterone into Dihydrotestosterone(DHT), but the enzyme will accept Finasteride as an alternate substrate; turning it into dihydrofinasteride through an enzyme bound, NADP-dihydrofinasteride adduct. Finasteride is similar in structure to testosterone and 5alpha-reductase has almost the same affinity for both molecules. However, Finasteride , having a high affinity for 5 alpha-reductase, covalently binds to the enzyme as a Michael acceptor, through a functionally irreversible reaction. However, the NADP-dihydrofinasteride complex breaks down with a half life of about 1 month at 37˚C., which is why patients must continue taking the drug.(.....)

=Medical Uses=Medical Uses

Finasteride is used to shrink an enlarged prostate, also known as benign prostatic hyperplasia (BPH), in adult men. This medication works by inhibiting 5a-reductase, which prevents conversion of testosterone to the natural body hormone, dihydrosestosterone (DHT) that causes growth of the prostate. Finasteride is specific for type II isoenzymes, resulting in a decline in serum DHT levels by 65-70% and in prostate DHT levels by up to 80-90% (source).