Androgens in Health and Disease.pdf - E Library

Chapter 8/Androgen Pharmacology and Delivery Systems 149
Fig. 3. Serum testosterone (T) concentrations (mean ± SE) befor (d 0) and after transdermal
testosterone applications on d 1, 30, 90, and 180. Time 0 h was 0800 h, when blood sampling
usually began. On d 90, the dose in the subjects applying T gel 50 or 100 was uptitrated or
downtitrated if their preapplication serum testosterone levels were below or above the normal
adult male range, respectively, The dotted lines denote the adult male normal range and the
dashed lines and open symbols represent subjects whoe T-gel dose were adjusted. [From
Swerdloff RS, Wang C, Cunningham G, Dobs A, Iranmanesh A, Matsumoto AM, Synder PJ,
Weber T, Longstreth J, Berman N, Testosterone Gel Study Group. Long term pharacokinetics of
transdermal testosterone gel in hypogonadal men. J Clin Endocrinol Metab 2000; 85:4500–4510.
© The Endocrine Society.]
women or children upon close contact with the skin. Transfer of transdermal testosterone
from the skin can be avoided by wearing clothing or showering after application.
This preparation has gained a significant market share of androgen formulations in the
United States, although it is marketed at a slightly higher price than the patches.
In addition to delivering testosterone through the skin, DHT gels have been marketed
in some countries in Europe. DHT cannot be converted to E 2 and will not produce
gynecomastia. It has been hypothesized that administration of DHT may have less
effect on prostate growth because it is not aromatizable. A decrease in estrogen levels
may decrease prostate growth because both estrogens and androgens are required for
the development of benign prostatic hyperplasia in dogs and possibly in humans. DHT
gel has been reported to be useful in the treatment of hypogonadal young and elderly
men (46–49). The DHT gel has been reformulated and the pharmacokinetics of
DHT at different doses (16, 32, and 64 mg applied to the skin) have been reported to give
total testosterone plus DHT levels in the low, mid, and high normal adult range (50).