A drug 'X' primarily reduces the static component of urinary obstruction in benign hyperophy of prostate and takes more than 3 months to exe its beneficial effect. Which of the following is 'X' ?

(Ref: KDT 6/e p294, 295) S-a-reductase inibitors are used to reduce the static component of urinary obstruction in BHP. It is delayed acting and takes more than 3 months to exe its beneficial effect. Selective a1 blockers are used to relieve the dynamic obstruction in BHP. These provide rapid symptomatic relief.