Finasteride: dosage, frequency & conception

[zenmunk]

I posted the following in another thread, but I thought it might be helpful as its own topic. This info is floating around in bits & pieces all over this forum, but collecting it all in one place may be useful.

 

In human clinical trials, the pharmacokinetic half-life of finasteride was found to be 6 - 8 hours. However, the pharmacodynamic lifetime of finasteride action, measured in terms of the drug's ability to reduce the systemic concentration of DHT, after a single oral dose of between 0.04 and 5mg, was greater than or equal to 7 days. See the first chart below (taken from the book entitled, Integration of Pharmaceutical Discovery and Development: Case Histories):

 

 

You can see how a single dose of the drug reduces the systemic concentration of DHT over a 7 day period. That leads one to believe that taking finasteride daily is probably not necessary to maintain one's hair count. However, it also leads one to believe that taking one dose every 5 - 7 days is probably unwise as well, because while the DHT remains reduced over the 7 day period it does slowly rise over that time.

 

Then the question is how often should one take finasteride? Based on the above chart, I'd say it would probably be pretty safe to take it every other day or even three times a week (MWF). You may even get away with twice a week (MTh).

 

The next question is how much (as in mg) should one take? Take a look at the charts below (the first three charts are from a Propecia study story (circa 1998) by Sherman Frankel, a University of Pennsylvania professor of physics):

 

 

You can see from the Serum DHT graph above that from doses of 0.2mg all the way through 5mg, the amount of inhibited DHT was about the same.

 

 

You can see from the Scalp Skin DHT graph above that from doses of 0.05mg all the way through 5mg, the amount of inhibited DHT was about the same.

 

 

You can see by the above graph that the dose dependence appears also in the accompanying rise in T, one-onehundredth the 5 mg dose being identical in its effect on the scalp skin testosterone.

 

 

The above graph (origin unknown) indicates how the following dosages of finasteride inhibit DHT:

 

- 0.2mg = 61.7%

- 0.5mg = ~65%

- 1mg = 68.7%

- 5mg = 69.2%

 

All pretty close in terms of percentages.

 

____________________________________________________________________________

 

 

I'm no scientist, but the first plasma DHT graph seems somewhat at odds with the rest of the graphs:

 

- 0.2mg reduces DHT to ~ 55 ng/dl

- 0.5mg reduces DHT to ~ 42 ng/dl

- 1.5mg reduces DHT to ~ 32 ng/dl

- 5.0mg reduces DHT to ~ 25 ng/dl

 

The first graph deals in blood serum levels. The rest in percentages of inhibited DHT. Unfortunately, I'm not sure how to compare the two. Perhaps plasma DHT levels of 55 ng/dl are not much different than levels of 25 ng/dl when it comes to preventing MPB? I welcome others more expert in these matters to chime in.

 

Regardless, I conclude:

 

It's probably pretty safe to take finasteride every other day or even three times a week (MWF). You may even get away with twice a week (MTh).

 

Dosage is a matter of personal experimentation. Merck recommends 1mg daily for optimal results. Maybe they are right, but when you consider the above information; the personal testimonials of many forum members who have successfully reduced dosages; and, the fact that Merck is a pharmaceutical company interested primarily in profits, then I think a healthy bit of skepticism is warranted.

 

If you want to save money and/or reduce side effects, I'd suggest tapering down slowly, and paying very close attention to any changes, until you reach a regimen which preserves your hair and eliminates sides. Keep a hair loss journal complete with weekly photos if it helps.

 

Perhaps something like this (if you're splitting 1mg Propecia tablets):

 

- 1mg every other day for one month. If still experiencing sides, but not losing hair, then -

- 1mg MWF for one month. If still experiencing sides, but not losing hair, then -

- 1mg TTh for one month. If still experiencing sides, but not losing hair, then -

 

- 0.5mg MWF for one month. If still experiencing sides, but not losing hair, then -

- 0.5mg TTh for one month. If still experiencing sides, but not losing hair, then -

 

- 0.25mg MWF for one month. If still experiencing sides, but not losing hair, then -

- 0.25mg TTh for one month. If still experiencing sides, stop the meds.

 

If one month at each dosage doesn't work for you, adjust to a time period which does. Obviously, if you start losing hair anytime during the tapering-off period, then you've gone too low and you have an important decision to make - do I up the meds again to preservation levels and deal with sides or just stop completely? Only you can answer that.

 

_________________________________________________________________

 

Regarding finasteride and conceiving children. I am aware of no evidence that men taking finasteride while trying to conceive will cause birth defects. Here is some information to consider according to Dr. Richard Lee:

 

- "In rabbit fetuses exposed to finasteride in utero from days 6-18 of gestation at doses equivalent to 5000 times the recommended human dosage, no evidence of malformations was observed. This result would be expected, since there was no exposure during the critical period of genital system development in rabbits."

 

- "When pregnant rhesus monkeys were given intravenous finasteride at a level equivalent to at least 750 times the highest estimated exposure of pregnant women to finasteride from semen of men taking 1mg/day, there were no genital abnormalities observed."

 

- "In the human embryo, the sensitive period of external genitalia development is during the 7th - 9th weeks of gestation. Although the chromosomal and genetic sex of an embryo is determined at fertilization by the kind of sperm, either Y-bearing or X-bearing, that fertilizes the ovum, male and female morphological characteristics do not begin to develop until the seventh week...Since the sensitive period of development of the external genitalia in the human embryo is the 7th to 9th weeks of gestation, there can be no danger to the child if the father is taking finasteride at the time of conception. Originally, Merck decided to err on the side of caution and warned against the possible problem of finasteride transfer in semen. This warning has since been removed from the package insert. Considering the medical/legal implications of a theoretically possible link of finasteride treatment to birth defects, it is reasonable to assume that Merck & Co. must be very confident in knowing that impregnating a woman while taking finasteride absolutely does not cause birth defects."

 

- "Nor is there any evidence of birth defects when the father taking finasteride has intercourse with the pregnant mother during the critical periods of sexual development. The in utero effects of finasteride exposure during the period of embryonic and fetal development (gestation days 20-100) were evaluated in the rhesus monkey, a species fairly predictive of human development. Intravenous administration of finasteride to pregnant monkeys at doses as high as 800ng/day (at least 60 to 120 times the highest estimated exposure of pregnant women to finasteride from semen of men taking 5mg/day) caused no abnormalities in male fetuses."

 

- "Still, Merck retains this admonition: "Women should not handle crushed or broken Propecia tablets when they are pregnant or may be potentially pregnant because of the possibility of absorption of finasteride and the subsequent potential risk to a male fetus. Propecia tablets are coated and will prevent contact with the active ingredient during normal handling, provided that the tablets have not been broken or crushed."

 

- "Considering that intravenous administration of finasteride to pregnant experimental animals during the critical periods of sexual development didn't cause birth defects, there is no reason to believe that transdermal absorption of finasteride from handling broken tablets could cause birth defects in the male child. But, since Propecia has not been approved by the FDA for use by women, Merck has nothing to lose by retaining this warning. In fact, it has good p.r. value."

 

- "So, can finasteride cause birth defects? Yes, there is a theoretical possibility that it can, but the probability is close to nil, when finasteride is taken in the recommended dosages. Since Propecia was approved by the FDA on 22 December 1997 and Proscar on 28 August 1996, millions of doses of finasteride have been taken and there has not been a single case report of a birth defect. Now that's reassuring information."

 

- "We do caution men who desire to father children to discontinue finasteride use two week prior to planned conception. Actually, there have been no reports of birth defects due to taking finasteride. But because birth defects can occur in women who have a DHT deficiency, the warning is mandated by the FDA for the 5mg. tablets."

 

Despite the above information, some guys (and their significant others) are still concerned about it. Something to keep in mind is the half-life for dissociation of the inhibitory complex between finasteride and its enzyme target is in excess of 30 days. Half-life is defined as "the time required for something to fall to half its initial value." So, it works out something like this:

 

Day 1 - 100%

Day 30 - 50%

Day 60 - 25%

Day 90 - 12.5%

Day 120 - 6.25%

Day 150 - 3.125%

Day 180 - 1.5625%

 

And, so on... So, at 6 months you still have around 1.56% remaining to be dissociated. That's also something to keep in mind regarding how long side effects can last for the average man (nevermind those who are genetically predisposed to severe side effects).

 

So, obviously, I don't know if or how finasteride could affect conception via semen. But if it can (which is what some are worried about), then discontinuing finasteride 2 weeks prior to planned conception, as Dr. Lee (and the FDA) prescribes, may not make much of a difference - it doesn't appear to be enough time. Unless the two week rule has something to do with the pharmacokinetic half-life or the pharmacodynamic lifetime of finasteride action, both being much shorter? If you have evidence that stopping for two weeks makes a difference, please present it. Based on the evidence thus far, it seems to me if you're going to stop for conception purposes, stop for the long-term, or don't bother at all. And, if you're going to stop for conception purposes, once your lady is pregnant, wear a condom for the duration of the pregnancy.

 

Lastly, there's little doubt that after the first month of discontinuation you will be losing hair that finasteride was preserving for you, so weigh the decision carefully.

 

z

Edited July 31, 2012 by zenmunk

[Boba909]

Awesome info, thanks so much for posting this!

[TakingThePlunge]

zenmunk,

 

Very thorough and thought provoking! I had experimented with a few dosing schedules until finally settling on MWF. It worked for me.

[Sean]

Zen, this is an outstanding post. Thank you so much for this info.

[zenmunk]

My pleasure, guys. I hope others find it helpful and convenient as well.

[21YearsAndScared]

I've got some questions,

Do you suppose reducing the frequency from everyday, to every other day would also postpone the "start time" of the drug? By that, I mean how people have said the drug does not work immediately, it takes a couple months, up to a year to start.

 

And following this, I would like to ask, what exactly takes time to start?

Do you continue losing hair for months until finasteride kicks in, or is it regrowth that's supposed to start?

 

I've been taking finasteride for a couple weeks now, of course I see no results - but what should I be expecting? Should I look for increase of density/thickness after a few months, or am I supposed to be looking for new growth?

 

What am I to expect from this drug?

[ShiningDome]

zenmunk,

 

Thank you for the post. I am considering finasteride, and after reading the extensive analysis on your post, I feel much better prepared!

 

This should be a "sticky" :-)

[orlhair1]

Great post. Thanks for putting this together! Even though I don't have any noticeable sides, I want to take the smallest dose to be effective. I was thinking about starting out just eliminating weekends so that I am taking 5 doses per week rather than 7.

[zenmunk]

I've got some questions,

Do you suppose reducing the frequency from everyday, to every other day would also postpone the "start time" of the drug? By that, I mean how people have said the drug does not work immediately, it takes a couple months, up to a year to start.

 

And following this, I would like to ask, what exactly takes time to start?

Do you continue losing hair for months until finasteride kicks in, or is it regrowth that's supposed to start?

 

I've been taking finasteride for a couple weeks now, of course I see no results - but what should I be expecting? Should I look for increase of density/thickness after a few months, or am I supposed to be looking for new growth?

 

What am I to expect from this drug?

 

I'm no doctor or pharmacist, so take my advice with a grain of salt. Always consult a physician expert in these matters before taking action.

 

Here are some finasteride observations:

 

- How does finasteride work? Testosterone floating in the bloodstream of the typical adult male routinely combines with an enzyme called 5-alpha reductase. The result of this interaction forms the more potent sexual hormone known as DHT (Dihydrotestosterone). When a man begins to lose his hair, certain genetically programmed follicles begin to develop DHT receptor sites. The DHT attaches itself to these receptor sites and begins to treat the follicle as a foreign object in the body. This chemical change not only affects hair. It can cause itching, inflammation, and oiliness. During this time, the follicle, under the attack of DHT, begins to miniaturize with every growth cycle, until after several years, it simply is too small and short to be seen. When finasteride is taken, it works to inhibit the formation of DHT in the system. Within a few months, the overall DHT levels will have remained low enough on a constant basis that the adverse effects DHT is having on the follicles will stop, resulting in a cessation of hair loss.

 

- When one first starts taking finasteride I suggest following Merck's directions - 1mg or 1.25mg (in the case of splitting proscar tabs) every day for a minimum of a year before evaluating the effectiveness of the results. If you experience mild-to-moderate sides, try to wait it out for a few months, without reducing dosage/frequency, to see if they resolve on their own; they often do. If they don't resolve, then consider reducing dosage/frequency. If you're having severe sides, you should discontinue using the meds.

 

- Finasteride starts to inhibit DHT right away, but it may take several months before you notice less hair loss. In fact, it’s likely that you will experience a shedding phase for the first few months (usually around 3-4) after which time the miniaturized hairs will (hopefully) be replaced by stronger regrowth.

 

- Finasteride seems most effective at the vertex and mid-scalp, but that doesn't mean one won't preserve one's hairline or even regrow some hair at the hairline. However, from what I can tell, impressive hairline regrowth is uncommon.

 

- Everyone responds differently to finasteride based on their unique physiology (similar to hair transplants). It may work wonderfully for a long time or it may not work at all or something in-between.

 

- It's very important to take the meds regularly. Having a set schedule helps to avoid missing a dose.

 

- If you discontinue finasteride you will eventually lose the hair the meds were preserving for you (usually within six months).

 

- After one has been on finasteride successfully for a while (I'd say a minimum of 1 year), then it may be OK to start experimenting with dosage/frequency in order to save money, reduce minor sides or simply because one feels better taking less meds. The key word is experimentation, but remember that experimenting (deviating from Merck's recommendations) may involve some degree of risk. In other words, you may lose more hair.

 

z

Edited August 10, 2012 by zenmunk

[zenmunk]

Great post. Thanks for putting this together! Even though I don't have any noticeable sides, I want to take the smallest dose to be effective. I was thinking about starting out just eliminating weekends so that I am taking 5 doses per week rather than 7.

 

I'd say you'd probably be in the safe zone if you cut out weekends, because DHT rises rather slowly over a 7 day period. Also, assuming you take 1mg/day, that's reducing finasteride intake from 7mg to 5mg per week - not a big reduction at all.

[zenmunk]

Here's another interesting find:

 

 

The chart above (from the Gisleskog study of finasteride and dutasteride) measures finasteride levels (not DHT) in the blood over a 24 hour period after a single 5mg dose. Apparently blood levels of the drug peak rapidly 2 - 3 hours after taking a dose and then drop sharply the rest of the day. However, the other charts indicate that DHT remains fairly suppressed for several days after a single dose.

 

I think that's why some people elect to split their dosage into morning and evening doses, because they believe it helps keep serum finasteride levels higher throughout the day, but I'm not sure if that affects DHT suppression. If it does, it's probably to such a small degree that it may not be worth the added inconvenience.

Edited July 31, 2012 by zenmunk

[stashthecash]

i searched this and found this thread thanks for the good info

[Boba909]

Bumping this thread up again! This thread should deserve more views.

 

PS: Has anyone tried dosing down on Finasteride?

 

I've been on 1 mg Propecia once every 2 days and so far I DO experience hair shed. HOWEVER, the time when I started skipping the dosage was also when I started using Rogaine foam.

[HairlessHero]

Zenmunk, thanks for your excellent post. Very insightful and useful for people on the drug and for those who are planing to start. I think if we can seek comments/thoughts from medical experts/doctors in this field, that would be more interesting to see what their views are. Thanks again.

[BrianR]

Nice work THANKS

[JohnnyDrama]

Excellent thread, and one in which is very topical to my own situation right now.

 

I experienced some ED last year while on 1.25mg daily, so for the past few months I've trying 1.25mg on MWF.

 

However, having met Dr. Feriduni last week and discussing medication in great detail as well as other things, he felt it might be in my best interests to do something like 0.5mg daily, instead of 1.25mg three days a week.

 

His reasoning (and I'm paraphrasing slightly, but it's along these lines) was that the body prefers when there is a steady, consistent stream of going through. So instead of a slight zig zagging of hormones by going the MWF route, the body would have a nice flat steady balance if 0.5mg was taken daily. I'm going to finish out my current dose while I have the 5mg tablets, but I reckon I'll switch to 0.5mg daily then, once I've gotten my hands on the 1mg tablet.

[ronzues]

What is the overall consensus on this?

 

I take 1.25mg every other day. Is that what most others take as well or should I be going every day?

[JohnnyDrama]

What is the overall consensus on this?

 

I take 1.25mg every other day. Is that what most others take as well or should I be going every day?

 

I see you started another thread on this but I thought it might be best to keep it on this one since it is very good.

 

Everyone will have their own reasoning as to how often they take the drug. Naturally the recommended is 1.25mg per day (well it's actually 1mg, but the 5mg tab is more popular and cheaper and therefore easier if split in four).

 

The majority of people that I have seen who are taking the drug every other day, are doing so because they didn't like how daily doses were going from a side effect point of view. Either that, or they are just beginning the drug and what to start on a smaller dose. Both make sense.

 

I started out taking 1.25mg every day for about 2 years. However, I noticed side effects, so I've now adjusted it to 1.25mg three days a week. The sides are not as intense now.

 

However, when I go to Dr Bisanga for my procedure in August, I'm getting a prescription for the 1mg tabs as I intend on switching my dose to 0.5mg per day. I feel that a steady, daily flow is slightly better than the up and down pattern that I discussed in my previous post.

 

The important thing is that you are taking Fin. If you can take 1.25mg per day without experiencing any side effects, then by all means take it every day. You will have the optimum level of protection against DHT.

 

All of the above is just my opinion however, but having spoken to several ht docs in person recently about it, I'm confident enough in it. It's essentially a case of you tailoring your own regimen to suit your body/needs.

[Raymond2013]

What a informative thread!

 

I've been taking 2.5mg MWF for 2 months now and haven't noticed anything bad. I've been thinking myself that it seems like a steady flow from 1.25mg a day would be better, but it's near impossible to get those pills in 4's and you end up with a bunch of crushed mess in the bottle and mg dosage becomes wishy washy.

 

I think the 1mg tabs would make life much easier. How much more is the cost? I'm paying $55 for 30 Finasteride 5mg pills.

[KO]

No, it's not that hard to cut them into 4. Just buy a pill splitter dude.

[peteson]

I think 5mg finasteride/Proscar is optimum. This is where I buy generic Proscar without a prescription http://instant-online-solution.com/ so I know it's a good strength.

Edited July 28, 2013 by peteson

[robben]

great work.

 

fin caused me dizziness after 9 days on it (1mg every day). so i stopped until the sides completely go. then, i will start with [2 pills / WEEK] and gradually make my way up. but this is different situation now: I'm not decreasing my dose after a minimum of year, but i'm starting from the BOTTOM, so i dont know if that will help?

[KD2020]

Anyone know how all of this works if taking Propecia and Androgel for Low T? It would seem that if Propecia prevented some testosterone from converting to DHT, them more testosterone would exist. Does anyone know or have any understanding on this?

 

And if one is using Androgel daily, should the Propecia be used daily?

[Shacked]

I think 5mg finasteride/Proscar is optimum. This is where I buy generic Proscar without a prescription http://instant-online-solution.com/ so I know it's a good strength.

 

Without a prescription? Sounds dodgy

 

Also, 5mg per day is the dosage to deal with prostate problems; not recommended to treat male pattern baldness. 1mg is optimum

[bonkerstonker]

David what is your finesteride intake now? Dose? days? Have you kept your hair with reduction?

 

I'm debating cutting down now from 1.25mg once a day to every other day. Because I've had thousands of grafts through nw5a shape I suppose I'm concerned my sides could widen if off finesteride maybe it would stay strong in 5a shape where hts been but widen to nw6

 

Does anyone else have any reduction experiences now as this post is a few years old.