Propecia half life? Looking for an official answer

[mm]

I have read various comments on how long propecia stays in the system.............but it is never by a doctor. Once and for all, could we get a doctor's on-the-record answer to this oft asked question?

[mm]

I have read various comments on how long propecia stays in the system.............but it is never by a doctor. Once and for all, could we get a doctor's on-the-record answer to this oft asked question?

[calvinmd]

You could get a specific answer, but it won't tell you what you probably want to know. It's not about how long Fin stays in the system. That's why you're finding conflicting answers about how long Fin's effects linger.

 

Finasteride actually stays in the system for a pretty short amount of time (a few hours, maybe days at the most). But the DHT-type#2 that was drastically reduced takes a lot longer to get replenished by the body and return to normal levels. (This is normal. The DHT#2 always builds slowly. But unless finasteride is there to wipe out the standing supply, your body would usually have a large amount of it sitting in the system at any given time because it get eliminated so slowly.)

 

Replenishing it takes a while. You'll get SOME DHT back pretty fast, but the 100% amount is gonna be a while. Several days even from just a few small daily doses of fin. Depending on how long & heavily you were dosing with Fin, it could even take weeks or a month to replenish the standing supply to FULLY normal.

 

And then, depending on how severely/long the DHT was being reduced, the timespan for the body's tissues/organs to fully "bounce back" could be even longer than that.

 

 

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[mm]

OK, simply put, can I get a doctor's answer to the following question:

 

What is the maximum amount of time I should allow between propecia doasges?

[Bill - Seemiller]

calvinmd,

 

Where are you getting your information? I'm not stating you are wrong necessarily, but from my readings, I have read that finasteride actually stays in the body for approximately 72 hours, hence the recommendation by SOME doctors to take .5 mg per day instead of the recommended 1mg per day. Some have argued that even .25 mg per day would be acceptable.

 

Again, my readings could be wrong, but since mm is looking for an "official" answer, I think siting sources would be helpful.

 

Bill

[Guest]

I am in Medicine - Clinical Pharmacology actually

 

Finasteride is a mechanism-based, reversible inhibitor of steroid 5-reductase. By inhibiting 5-reductase, finasteride blocks the production of the DHT from its precursor testosterone.

 

Finasteride forms an inhibitory complex with the enzyme that is tight and has a low rate of dissociation. For practical purposes, the binding is so sustained that you could assume that Finesteride serves as a sort of irreversible inhibitor of steroid 5-reductase.

 

Orally finasteride will its peak plasma concentration between 1.8 and 2.8 hours post dose. The drug half-life in terms of concentration in blood is 4.7??“7.1 hours. However beacuse of above the drug has a prolonged effects on serum levels of DHT. Within 4 hours of a single oral dose then DHT levels in blood can be been to be suppressed and remain so for >72 hours. In patients receiving multiple doses of 1 mg of finasteride once daily for 7 days, the serum levels of DHT will be significantly suppressed, relative to for up to 7 days after administration of the final dose. The pharmacological effects of finasteride action therefore last a lot longer than blood levels. The recovery of circulating DHT levels after 72 hours has been suggested to reflect the half-life of new enzyme synthesis, not the half-life of the drug..

 

Reducing the dose of Fin simply will reduce the bllod levels achieved. Over time this will mean a reduced effect to inhibit DHT, i,.e. less effect. The 1 mg daily dose has been set as the dose that achieves long term effective inhibition of the DHT leading to improvements in hair cycle.

[Bill - Seemiller]

Sparky,

 

Any chance you work for Merck?

 

Just wondering...

 

Bill

[calvinmd]

Honestly, I'm not exactly sure where I read that info anymore.

 

When I first was investigating the idea of taking something for MPB, I was just reading everything I could find on the issue of hormonal drugs. (Testosterone, DHT, Estro, etc.) I read a bunch of MPB articles, websites, body-building info on similar subjects, various message boards, etc. I even talked a little bit with a couple of friends who work in the pharamceutical & medical fields.

 

That description about Fin's effects on the system came from that load of reading/digging, but I'm not sure exactly where I first heard it. I think it was talked about that way in more than just one place, though.

 

 

Either way, the idea that it wipes-down the "standing" levels of a drug that take a while to replenish themselves makes a lot of sense to my mind. It explains why the drug can have such a short life in the system, and yet it still seems to be capable of affecting people's bodies for much longer periods of time when they get side effects from it. The Finasteride itself might be outta the body within days, but the body's naturally slow regeneration of DHT will make Fin's effects linger for a longer time.

 

(So the Fin users aren't lying when they complain about the side-effects lingering for weeks & months after stopping. But the drug researchers aren't lying either when they insist that Fin is totally out of the body within days.)

 

It also means that taking Fin every other day (or even longer intervals, or at different times of the day, etc) is probably fine. What's really relevant is the net amount of fin that's "averaging" in your system week-by-week and month-by-month.

 

 

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