Hair Loss

J Androl. 2008;29:514

The effect of 5 alpha-reductase inhibitors on erectile function.
Canguven O, Burnett AL.

Conclusions ( edited for hair loss blog use)

…”Finasteride and dutasteride are approved for use in the treatment of men with symptomatic BPH and pattern hair loss and are also under study in ongoing prostate cancer prevention trials. It was shown that treatment with 5ARIs results in a reduction in median serum DHT levels by 60%–93% after 2 years. According to 13 randomized studies in which finasteride was used alone, erectile problems occurred in 3% of the men studied long term. This percentage of ED would seem minimal, and it is also noteworthy that this adverse event diminished by half over time in men taking finasteride. Randomized controlled studies report the rates of erectile dysfunction to be between 0.8%–15.8%. The placebo effect demonstrated by Mondaini and associates has to be taken into account when relating the effects of 5ARIs to ED. On the other hand, ejaculation disorders (premature or retarded) related to the use of these inhibitors has not been reported in detail. This outcome should be better described in further studies.

Although there are controversial studies, as a best example we should look for 5 -reductase–deficient men whose mean plasma DHT levels are significantly lower when compared with those in normal subjects. More remarkably, the subjects have normal erections directed towards females, although they have low DHT levels (Imperato-McGinley et al, 1974).

Previous studies have shown that there does not seem to be a strong cause-and-effect relationship between serum androgen concentrations and erectile function; even in severely hypogonadal men, the erectile response is not always lost, and T treatment of hypogonadal men with ED does not necessarily restore lost erectile function (Mills and Lewis, 1999). Studies also verified that MENT, which is resistant to 5 -reductase, is able to provide physiological and behavioral androgen replacement in hypogonadal men and may provide indirect evidence that 5 -reduction is not required for mediation of the influence of T on these behaviors in men.

Testosterone and dihyrotestosterone perform vital functions in various organs….. DHT is more active in prostate than T. This may be due to the fact that DHT is largely a paracrine hormone and exerts effects in tissues of its origin. On the other hand, T is more relevant than DHT in erectile function, which requires central and peripheral androgenic activity. T exerts both humoral endocrine and local paracrine effects.

Snip…. It is likely that androgens are vital for the development, maintenance and function of penile tissue and regulation of erectile physiology. However, the critical androgenic substance for these effects is most likely T rather than DHT.

Dr Proctor comments: It is likely the fact that testosterone is more important than DHT for erectile function helps keep down side-effects in use of finasteride (propecia) for hair loss treatment.

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