Absorption of testosterone gel 1% (Testim) from three different application sites

A popular treatment choice for male hypogonadism is topical testosterone gel. Two proprietary formulations, Testim Gel 1% (Auxilium Pharmaceuticals, Malvern, PA, USA) and AndroGel 1% (Solvay Pharmaceuticals, Marietta, GA, USA), are available. The recommended Testim application site is limited to the arms/shoulders, whereas AndroGel may be applied to the abdomen, shoulders, and upper arms.

To compare absorption variability when applying Testim to various body sites.

Total testosterone (TT) and calculated free testosterone (CT(free)).

Hypogonadal men (TT < 300 ng/mL) applied Testim to three distinct anatomical sites for 1 month per site: arms/shoulders (A), chest/abdomen (C), and calves/legs (L). Pretreatment TT and CT(free) were compared with end-of-month measurements. Safety was assessed with prostate-specific antigen (PSA) and hemoglobin (Hb) measurements.

Twenty-one hypogonadal men (age 56.9 +/- 9.0) naïve to prior testosterone therapy and otherwise in good health participated. Three groups of seven applied Testim in the sequence ACL, CLA, and LAC. Overall TT and CT(free) increased significantly over pretreatment levels (P < 0.0001) into the normal range. Application sites differed with regard to TT levels achieved, A > C >or= L (P = 0.011). No significant sequence effects were observed, however, the ACL group achieved the highest levels. CT(free) correlated well with TT in all men (R(2) = 0.87) and by application site (R(2) = 0.91, 0.85, and 0.86 for A, C, L, respectively). Pre- and post-treatment PSAs were similar; mean pretreatment Hb increased from 14.7 +/- 1.47 to 15.5 +/- 1.3 g/dL at month 3. Hemoglobin corrected to normal in four subjects with anemia at enrollment (Hb < 13.5 g/dL).

Testim Gel 1% applied to various anatomical sites increases TT and CT(free) into the normal range; the best levels are achieved with arms/shoulder application. Flexibility in the application site of Testim is possible if TT or CT(free) is monitored to ensure adequate therapeutic levels. Anemia, possibly associated with testosterone deficiency, was an incidental finding in several men and was corrected with topical testosterone replacement.