Do I have to Take Propecia Instead of Proscar?

Q:

I have a question about Finasteride for Dr. Mohebi, based on a consultation with another doctor. The other doctor recommended for me to take Propecia instead of the generic Proscar. When I asked him why, he said that in the 5mg generic tablets you need to cut them into quarters, and that the medicine might not be evenly distributed, therefore I might get above or below the recommended dosage on a daily basis. I just wanted to see if Dr. Mohebi has ever heard of this and if he would recommend the name brand Propecia over the generic Proscar, despite the difference in costs.

A:

You asked a good question, I will explain it to you in further detail. Finasteride has a serum half-life of about 6 hours, which means in about 6 hours, its serum level drops to half, but the important factor is the functional half-life of Finasteride (Proscar). Finasteride as you probably know helps hair loss by blocking an enzyme called alpha reductase inhibitor that blocks the conversion of testosterone to dihydrotestostrone (DHT).
The half-life of Finasteride/enzyme complex is about 30 days, which means even if you stop taking Finasteride it takes several weeks for the DHT level to get back to baseline. This is why some people take half tablet of Proscar every other day without noticing any significant difference in its effect. So it will not make a difference whether or not you take a little more than ¼ tablet today or a little less tomorrow as long as you take 5 milligrams of Finasteride within 4-5 days.