Finasteride and Allopregnanolone
Is it true that Finasteride in Humans would reduce important Neuroactive Steroids like for example allopregnanolone? I know there was already a post about this in the past but that was about rats. In rats, Finasteride blocks both type I and II 5α-reductase whereas in humans inhibits only type II which it seems is not present in the brain unlike type I. I would appreciate your opinion about the following two studies:
Link 1: Finasteride Treatment and Neuroactive Steroid Formation (PDF file)
I do not think I can add much here, as I am not a biochemist. Mood changes have been associated with finasteride and depression has been reported, but I’m unclear on specifics beyond that.
The 1st link is a study of 20 men with an average age of 69.5 years that took 5mg finasteride. The 2nd link is a study of a dozen men that took the 1mg finasteride with no listed ages that I see. Both studies are small and offer nothing definitive, using words like “probably” and “might”.
This should go without saying, but finasteride is an elective medication with some rare side effect possibilities and is available by prescription only. Hundreds of other medications also come with side effect risks, and you must talk with your doctor about these risks and benefits so you can make an informed decision.
Another point to make is that depression and mood changes have not been found as a reported side effect from any clinical trial i’ve seen. It’s possible that in extremely rare cases this could happen, but it’s probably in the same realm of experiencing a serious life threatning reaction to Asprin.
That being said, it’s definitely possible that finasteride is reducing total allopregnanolone levels in the human brain. However, it’s pretty clear that its either reduced by an insignificant amount, or the amount these levels are reduced does not lead to any problems.
These results are about serum levels which means, if I’m not mistaken, about what is and is not present in the circulating blood. Allopregnanolone and the other neuroactive steroids are needed in the brain. So the biq question is, if these steroids are reduced in the circulating blood -and according to the clinical trials that’s the case-, does that mean that it is also lowered in the brain? Considering that there is such a thing as the brain blood barrier, the answer is not obvious.
Allopregnanolone needs the enzyme 5ar to be produced, but according to what I have read, in the human brain only 5ar type I is present and Finasteride inhibits only type II. Now, assuming that these neuroactive steroids are formed in the brain, then it must be 5ar type I that is responsible for this conversion. Therefore, the way I see it, there’s something that does not square up here.
Now, let us for a moment assume the worst. Let us assume that Allopregnanolone is very important for a healthy brain and let us also assume that finasteride does really reduce it drastically inside the human brain. Considering that finasteride does not target it directly but only target the enzyme that is responsible for its formation, then why not take supplements of Allopregnanolone? The problem is that I did not find anyone who sell such a thing. What I found was Pregnenolone supplements. Perhaps someone should consider the idea of producing and selling it. I think many of those who take Finasteride would but it.
As a follow up to Joe – You are right that allopregnanalone requires 5AR Type 1 for production. Finasteride is *supposed* to only inhibit 5AR Type 2. However, from the clinical measurements I presented it is virtually undeniable that finasteride lowers allopregananalone and I have spoken with specialists that believe finasteride inhibits both types of 5AR which is the case for dutasteride.
SeattleMD did raise a valid point that the most important factor is whether allopregnanalone is reduced by a clinically significant amount. As you have seen, the amount is 70%+ reduction (not insignificant by any relative measurement). Reducing any biological molecule or substance by 70% is extremely likely to produce clinical effects. However, given the difficulty of measuring allopregnanalone levels in the brain I imagine it would be very difficult to find any research that has delved into this issue. Absence of proof is definitely not proof of absence however, and a little common sense will alert you to the fact that finasteride is not nearly as innocuous as these hair transplant would like to have you think.
You’ve just got to give it a go and see how well you can tolerate the drug.
Personally I think whatever the side effects if it was 100% effective for the front middle and crown almost 100% of balding guys would take it and use other drugs to deal with any side effects that arose. Alas for most it’s not.
SeattleMD, where is this information about Jeremy being a shill? I honestly don’t believe that is true, even though I agree with everything else you said. He is strongly opposed to finasteride, but I don’t believe it’s for any financial gain.
I am on finasteride for almost one year. I experience better mood actually. Touchwood. My cousin who is using finasteride 1% for almost 10 years..has not experienced anything till now.
“and I have spoken with specialists that believe finasteride inhibits both types of 5AR which is the case for dutasteride.”
Yes, it is known that Finasteride lowers also type I 5AR but this reduction is very small and it certainly cannot explain a 70% reduction of Allo.
Tex – SeattleMD chooses not to respond to my statements about the science, probably because he has not done the research and instead he has decided to falsely accuse me of working for a law firm. What he does is despicable since he is trying to poison the well without giving any of my valid arguments consideration.