Testosterone gel application sites for maximum DHT

[trtthings]

Hi all,

Wanted to know if anyone knew this.

I'm aware that likely genital skin/scrotum is richest in 5a-reductase and thus yields the most DHT from topical testosterone (gel or cream).

Does anyone know which site comes after that? From what I've read the sheer amount of skin you apply on (surface) matters as well. But it seems even better if the 5a-reductase expression is great, such as on the balls.

@Cataceous
@madman

 

[trtthings]

"Thus, the present study demonstrates that the 5α-reductase activity is mainly located in the apocrine sweat gland and sebaceous gland. This suggests that 5α-reduction of testosterone is an important step in mediating the action of androgens in these tissues."

This is interesting. I'd guess the armpits might be of interest, seeing as we sweat a ton from there, additionally the skin is thin so we'd be seeing reasonable absorption (if not too hairy).

 

[trtthings]

"In the skin the activity of the type 1 5α-reductase is concentrated in sebaceous glands and is significantly higher in sebaceous glands from the face and scalp compared with nonacne-prone areas (Thiboutot et al, 1995)."

 

[trtthings]

Northern blot studies revealed most abundant type 1 mRNA in neonatal foreskin keratinocytes, followed by adult facial sebocytes, and stronger expression in DP from occipital hair cells than from beard (Chen et al, 1998a).

 

[trtthings]

The beard DP cells appeared to generate more 5α-DHT than those from nonbalding scalp hair follicles (Thornton et al, 1993)

 

[Cataceous]

It looks as though you've basically answered your own question, or at least tracked down much of what's known. Just as peripheral information I'll add that emphasis on the total skin surface area has a reasonable basis. The 5α-reductase enzymes can become locally saturated. Thus you might get more DHT if you spread a low-concentration transdermal product over a large area than if you spread a high-concentration product over a small area—even when total testosterone delivered is the same.

Regarding application to the armpits, I was reminded of the Axiron product. In a study its effect on DHT is characterized this way: "DHT concentration increased in parallel with testosterone concentration during AXIRON treatment. The mean steady-state DHT/T ratio remained within normal limits and ranged from 0.17 to 0.26 across all doses on Days 15, 60, and 120."[R] What catches my attention is that DHT/T ratios of 17-26% are a good bit higher than the figure of 10% that's typically cited. As a further aside, guys would sometimes shave their armpit hair in order to use Axiron more efficiently.

 

[Nelson Vergel]

Great Thread, Guys!

 

[Nelson Vergel]

Pharmacokinetics of testosterone cream applied to scrotal skin

Conclusion *we concluded that the scrotal administration of testosterone in a cream formulation provides high bioavailability, dose-dependant peak serum testosterone concentration, and tolerability with a much lower dose relative to the non-scrotal transdermal route *further studies of...

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