Transdermal testosterone administration in hypogonadal men: Comparison of pharmacokinetics at different sites of application and at the first and fifth days of application

In this study of 13 hypogonadal men (25-69 years of age), three open-label, randomized treatments were administered to determine the pharmacokinetics of serum testosterone after application of an investigational testosterone transdermal system to the upper buttocks, upper arm, and back. Testosterone in vivo input kinetics profiles were estimated by DeMonS, a recently developed numerical deconvolution method for estimating drug absorption at different time intervals and/or drug disposition model parameters, and compared on the first and fifth days of system application. Area under the concentration-time curve from 0 to 27 hours (AUC(0-27)) values for testosterone after one-day applications to the upper buttocks, upper arm, and back were 9,560 ng . hr/dL, 8,651 ng . hr/dL, and 8,988 ng . hr/dL, respectively. Maximum observed concentration (C-max) values were 482 ng/dL, 462 ng/dL, and 499 ng/dL, respectively. Serum testosterone concentrations were equivalent to each other, and C-max values fell within the normal range. No drug accumulation was seen with repeated dosing over 5 days.