Finasteride is a 5 alpha reductase type II inhibitor. Blocking testosterone to DHT conversion in the hair follicle and prostate.
An alpha blocker is a drug that blocks the alpha adrenergic receptor. They're used to treat high blood pressure and even prostate conditions.
These two drugs do not use the same receptors, but call a doctor if you're concerned.
Also, using these drugs synergistically is quite effective at treating prostate problems such as BPH.