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How does Finasteride affect 5 AR Type 2 and Type 1 and DHT levels

DR. MILLER: This is, again, clarification on the Type I and the Type II 5-alpha-Reductase. Does finasteride have any effect on Type I at all? And in your study, you know, you really didn't measure Type II, but yet, you're saying, you know, reasonably dogmatically that it's working just on the Type II, and yet, we know that the Type I is in the skin and in the sebaceous glands, and is there a way to measure just hair itself for this enzyme?

DR. HARRIS: We know that there is--

DR. MCGUIRE: Could you identify yourself?

DR. HARRIS: Georgianna Harris.

We know that there is a hundredfold difference in the affinity of finasteride for the Type I and Type II enzyme, and we do know about the localization of Type I and Type II in scalp, if you would like to see. We can't measure separately, you know, inhibition in hair follicles versus the remainder of the scalp. Did I answer the question?

DR. MILLER: I just wondered, because we're saying, you know, that it's Type II that--and there's also some affinity for Type I, though, too.

DR. HARRIS: Well, we know from circulating DHT that there is residual DHT that we now know is due to the Type I 5-alpha-Reductase from the clinical studies.

DR. WALDSTRAICHER: Let me just share some experience that we've had with finasteride, which is the Type II inhibitor, obviously, that we're discussing today. Over the years, we have gone up to very high doses of finasteride for the development of Proscar, our 5-milligram dose. Even up to 80 milligrams of finasteride, you don't actually get more than about the same 70 percent suppression in DHT that you get with even lower doses of finasteride.

If it would have an effect on the Type I enzyme, it would suppress DHT even further, probably down to detectable levels. In fact, we have done an experiment with a Type I 5-alpha-Reductase inhibitor which we have, and if you take patients on finasteride who have this 70 percent suppression of DHT and add just a touch of the Type I 5-alpha-Reductase inhibitor, very easily, within a day or two, you can suppress DHT down to the lower limits of sensitivity. So, does that answer your question?


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