Penile fibrosis (2 studies)

[Fanjeera]

http://www.ncbi.nlm.nih.gov/pubmed/22375859
http://www.asiaandro.com/archive/1008-682X/5/33.htm (9-week-old rats actually are already sexually matured and adults)

What do you think?
If you don't take the medicine too long, it doesn't have to mean a significant change in erectile function, because castrated men can also have sex, but it can probably change the length of your flaccid penis.

 

[IrishFella]

2 studies involving rats? Has there been any incidences in the studies involving humans? Official studies, not PropeciaHelp reports.

 

[Wuffer]

I believe the rats were given something over a hundred times the human Propecia dose (per pound of body weight). Finasteride is for the most part a flat dose response medication, but when you take 100X the normal dose you never know what's going to happen.

Animal studies are never directly applicable to humans. The rat penis also functions quite differently than the human penis, since it is equipped with a coupling mechanism that sort of 'locks' it in during coitus. Obviously humans don't have this feature, and the fact that the organs function differently means they react differently to androgens. These studies generate some interesting hypotheses, but existing human data seems to contradict these findings to some degree.


Just an interesting note to add, I remember seeing another study done on humans that indicated free T levels were significantly reduced by finasteride. However, the second study here on the rats only saw a reduction of free T levels in the castrated groups. This is a further indication that rats and humans are likely going to react quite differently to the drug, so the findings of studies like these don't really tell us much except for how rats respond.

 

[Fanjeera]

Thank you for the last two parts of your posts! This kind of information is very valuable.
But the rats weren't actually given that much. First, their metabolism a lot faster than human's. And their DHT levels dropped to almost exactly as much as in human's, so the degree of inhibiting 5ar2 has to be the same.
You can't so easily make such studies on humans. The only way to get the tissue is when placing a penis implant. And the men who go through this procedure are of course impotent, but the changes in the tissue are similar to rats taking finasteride.
There is some more proof though: the info sheet now says that finasteride can cause persistent sexual sides.

 

[Fanjeera]

Can you tell me how the rat penis locks?

 

[Wuffer]

I believe the first study you posted was the one where they gave the rats a massive dose of finasteride, but it doesn't specify in the abstract; I could be wrong, but I recall seeing another study where this was the case. The one done in China looks like they gave them around 10x that of a normal human dose.

The rat penis has a baculum and I believe this aids in the locking mechanism during coitus. It is essentially a penis bone; a feature that humans obvious do not possess. This alone makes the penis function and behave quite differently, and could mean that the organ responds differently to androgens.

I'm not saying there might not be some truth to these or that they have absolutely no applicability to humans. As it stands though, they are very small animal studies, and 'officially' they have zero applicability to humans. Further studies need to be conducted to draw anything useful from these. I'm not sure if a biopsy of the human penis would yield anything useful, but that could be an option if this were to be studied in humans.

 

[Fanjeera]

Both studies dosed 4,5 mg/kg a day. The DHT drop is similar to humans (even a little bit smaller), therefore the effect isn't massive, but similar. They tried to diagnose a study to directly research the ED side effect of the drug found in humans, so would they use an absurd dose?

 

[Fanjeera]

http://onlinelibrary.wiley.com/doi/10.2164/jandrol.112.017012/pdf
I now happily take back this theory of irreversible damage in the light of this lately done study. Looks like even this tissue can restitutio ad integrum, when the hormones get back in place again. Thank you for the patience!

 

[Quantum Cat]

so you no longer believe Finasteride can cause physical irreversible changes to penis size/girth?

 

[Fanjeera]

That's right. If even a castrate's penis recovers after delayed testosterone replacement, why can't it be the same with DHT depletion and recovery?