Transfer of transdermally applied testosterone to clothing: a comparison of a testosterone patch versus a testosterone gel.
OBJECTIVE
To assess the amount of testosterone transferred from the abdominal application sites of a transdermal testosterone patch and a transdermal testosterone gel to cotton T-shirts worn for 24 hours during each treatment.


METHODS
During a crossover study comparing the pharmacokinetics of a testosterone patch versus a testosterone gel in 28 hypogonadal men, subjects wore fresh cotton T-shirts for 24 hours on the seventh and fourteenth days of each treatment and during a 24-hour baseline period. At the end of each evaluation, the abdominal section of the shirt was carefully cut out, extracted in alcohol, and analyzed for testosterone by a direct radioimmunoassay. The minimum quantifiable amount of testosterone was 0.03 microg per T-shirt sample.


RESULTS
The median amounts of extracted testosterone were 0.44 microg for the baseline samples, 25.4 microg for the average of the two patch samples, and 6,762.7 microg for the average of the two gel samples (all comparisons P < 0.0001). Significant correlations were observed between the day 7 and day 14 data for both the patch (R = 0.4982; P < 0.01) and the gel (R = 0.8383; P < 0.0001). No significant correlations were found between the baseline, patch, or gel data, or between these and any demographic or pharmacokinetic parameters. A quantitative interpretation of the findings suggests that the baseline results are consistent with the transfer of testosterone in sweat; the patch results are probably due to the transfer of a small amount of residual testosterone left on the abdominal skin from the prior day's patches; and the gel results reflect the desquamation of stratum corneum containing a portion of the abdominally applied testosterone.


CONCLUSIONS
There are large differences in the amount of testosterone that can be transferred from the application sites of transdermal patches and gels. The latter should be covered with clothing to minimize transfer through intimate skin-to-skin contact.
Mazer
Norman
N
Watson Laboratories, Inc., Medical Affairs, Salt Lake City, UT 84124, USA. t42nam@comcast.net
Fisher
Daniel
D
Fischer
Jerome
J
Cosgrove
Michael
M
Bell
Damon
D
Eilers
Barbara
B
D000005:Abdomen; D000279:Administration, Cutaneous; D000328:Adult; D000368:Aged; D000728:Androgens / Q000008:administration & dosage* / Q000032:analysis*; D003020:Clothing; D032561:Cotton Fiber; D018592:Cross-Over Studies; D005782:Gels; D006801:Humans; D007006:Hypogonadism / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D016032:Randomized Controlled Trials as Topic; D012044:Regression Analysis; D013739:Testosterone / Q000008:administration & dosage* / Q000032:analysis*
D000728:Androgens; D005782:Gels; D013739:Testosterone