Transdermal formulas bioavailabilty

It really depends on the transdermal. Between the misinformation and other bad practices 10% might be right. i am familiar with dmso and am confident that the actual figure is much higher than 10%.

The best formula seems to be that containing:

40% alcohol isopropyl
30% IPM
10% oleic acid
10% DMSO
10% propylene glycol

I wonder if I could just use plain alcohol 97� instead of alcohol isopropyl, thanx

Androgel delivers only 10%:

"Approximately 10% of the Testosterone dose applied on the skin surface from AndroGel is absorbed into systemic circulation. Therefore, 5 G and 10 G of AndroGel systemically delivers 5 mg and 10 mg of testosterone, respectively"

(From Androgel prescribing information)

Testim, a new product claims 30% more bioavailability than androgel, giving 13% bioavailability. Interestingly, the AUC for free T for Testim is 47% greater than androgel. Only having the abstract I don't know why that would be:

" target="_blank"> http://www.ncbi.nlm.nih.gov/entrez/...bstract

On the other hand I've seen bioavailability as high as 60% for gel based topical estrogen:

http://www.ncbi.nlm.nih.gov/entrez/...8&dopt;=Abstract

So who knows.

I'd say it depends on the application site, cleanliness and amount of dead skin. Spots with thin skin IMHO should yield higher penetration. Agel specifically calls for abs and upperarm, areas with thicker skin as application sites. These areas allow for 10% penetration only. One could also include penetration enhancers such as phlogel, capsicum, aloe...... I wonder however how much does get absorbed via scrubbed forearm applications though....

Nandi, did you mean 5g and 10 g of Androgel deliver 50 mg and 100 mg respectively systemically?

Androgel contains 1% testosterone. So a 10 G (10 gram) packet of androgel contains 100 mg of testosterone. 10% of this is absorbed, yielding an absorption of 10 mg of test. This is at the high end of a man's normal daily production.

The scrotum has the best absorption of any part of the body (except of course in women, where the vagina has the best absorptive properties). The problem with applying test to the scrotum is scrotal skin is rich in 5 alpha reductase, so a lot of DHT is produced.

Posted by: Nandi12

The problem with applying test to the scrotum is scrotal skin is rich in 5 alpha reductase, so a lot of DHT is produced.

But as far as DHT isn't directly produced by prostate and/or scalp 5AR there should be no problem, shouldn't it? Or does the DHT produced at the scrotum produce, in turn, high enough serum DHT levels as to be able to give you side effects when that blood reaches scalp/prostate ??

Posted by: Nandi12

Androgel contains 1% testosterone. So a 10 G (10 gram) packet of androgel contains 100 mg of testosterone. 10% of this is absorbed, yielding an absorption of 10 mg of test. This is at the high end of a man's normal daily production.

The scrotum has the best absorption of any part of the body (except of course in women, where the vagina has the best absorbtive properties). The problem with applying test to the scrotum is scrotal skin is rich in 5 alpha reductase, so a lot of DHT is produced.

DHT production, specially in the groin area is desirable if one is after libido increase. Srotal/penile application of alcohol based transdermals takes someone with a higher pain threshold then me.
Incidentally, all transdermals have relatively high DHT conversion due to presence of folicles at application site

quote:

---

But as far as DHT isn't directly produced by prostate and/or scalp 5AR there should be no problem, shouldn't it?

Bear in mind that (to the best of my knowledge) there have been only two short term trials of transdermal DHT involving small numbers of men. These are the studies suggesting that systemic DHT is either beneficial or at least not harmful to the prostate. I'm sure the manufacturers of Androgel are (wisely) erring on the side of caution when they instruct patients not to apply Androgel to the scrotum because of elevated DHT production.

Posted by: Nandi12

Bear in mind that (to the best of my knowledge) there have been only two short term trials of transdermal DHT involving small numbers of men. These are the studies suggesting that systemic DHT is either beneficial or at least not harmful to the prostate. I'm sure the manufacturers of Androgel are (wisely) erring on the side of caution when they instruct patients not to apply Androgel to the scrotum because of elevated DHT production.

My point was that I thought that serum DHT was just going to be too little, specially in comparison to the DHT produced locally at scalp/prostate by the specific 5AR in those tissues.
It's kind of like when you use injectable test, then some test reach scalp,prostate,skin,... 5AR and some of the DHT produced rebounds to the blood... I say this because I thought that blood DHT was very insignificant compared to locally produced DHT, but perhaps I am wrong, ain't I?

I don't think it is a matter of anyone being right or wrong; there aren't enough data to make a firm conclusion. What the manufacturers of Androgel are concerned about is convincing a jury that local production of DHT in the prostate may be the culprit behind BPH and cancer, when the plaintiffs will parade countless experts in front of the jury claiming otherwise. It's just not worth the risk.