Missing Propecia and Minoxidil Dosages, in Theory
A group of experts in the hair restoration field, were polled on the issue of dosing minoxidil and finasteride. What I am quoting below are some unofficial opinions that are not the standard FDA line for these drugs. I present them for the interested readers on this blog. The authors of these thoughts would rather not identify themselves, as these opinions are not in-line with standard treatment recommendations, even for the doctors who believe what is written below…
Comments on minoxidil:
Once a day topical dosing with minoxidil is probably close to, or equivalent to, twice a day. When given orally, minoxidil has a relatively short half like of several hours, but when topically applied, it has a half life of 22 hours in the skin. This makes once a day dosing a very reasonable option which I often suggest to patients.
Comments on finasteride:
Unfortunately, there are no references in the literature, that I am familiar with, concerning the “functional” half like for finasteride.
The serum half life of finasteride is only 4-6 hours. If we assume the worst, 4 hours, then there is far less remaining from a 5 mg dose 48 hours after dosing than there is from a 1 mg dose 24 hours after dosing. Similarly, a 2.5 mg dose does even less well. So, from a simple serum level of finasteride standpoint, every other day 2.5 or 5 would not maintain consistently high enough serum levels.
It gets interesting though when you consider the half life of the finasteride / reductase complex. The half life of this blocked enzyme complex is around 30 days. This is the most likely reason that when you stop taking finasteride (after chronic dosing), it takes 3 months for your DHT levels to return to baseline. This part of the story implies that, once you get up to steady state levels, every other day dosing would surely be enough..
I just think that there might not be enough of the drug around to keep the enzymes saturated using chronic alternate day dosing. These are the reasons that I recommend daily dosing but point out to my patients that it doesn’t matter if you miss a dose now and then.
This is the type of information that I, for one, am most interested in. Do you have any other recommendations and advice from experienced clinicians?
And though this blog is already weighing heavy with it, I think like jello, there is always room for thanks, so thanks for keeping this blog so up to date Dr. Rassman.