Mechanism of action of finasteride is -: (A) Androgen receptor antagonist, (B) 5 - a reductase inhibitor, (C) 17 - a hydroxylase inhibitor, (D) Aromatase inhibitor
Answer is B. Ans. is 'b' i.e., 5-a reductase inhibitor Finasteride* Competitive inhibitor of enzyme 5 a reductase, which converts testosterone to more active DHT (Di hydro testosterone) which is responsible for majority androgenic actions, including the actions on prostate and hair follicles.* It is relatively selective for 5 a reductase type 2 isoenzyme which predominates in male urogenital tract, and is used in BPH, i.e., Benign prostatic hyperplasia to shrink the prostatic size and increase peak urinary flow rate.* It has also been found effective in male pattern baldness.Adverse effects* Decreased libido, impotence, decreased volume of ejaculate.* Gynecomastia, skin rashes, lip swelling may occur.