Background: Topical effects are the most common adverse event for the scrotal and nonscrotal transdermal testosterone systems.
Objective: The study compared topical irritation rates for scrotal (Testoderm Testosterone Transdermal System; ALZA Corporation, Palo Alto, CA) and nonscrotal (Androderm Testosterone Transdermal System; SmithKline Beecham Pharmaceuticals, Philadelphia, PA) products.
Methods: This open-label, crossover study randomized 60 healthy, adult males to 14 days each of two treatments: one 40-cm2 scrotal system delivering approximately 4 mg testosterone over 24 hours, or two 37-cm2 nonscrotal systems worn on the back or upper outer arm, providing approximately 5 mg testosterone over 24 hours. Severity of topical effects was scored at system removal.
Results: Allergic contact dermatitis and spontaneous flaring of prior application sites occurred in 7 (12%) subjects using nonscrotal systems on Day 12; no confirmed cases of allergy to the scrotal system were observed (p < 0.001). For scrotal and nonscrotal systems respectively, moderately intense irritation was noted immediately after system removal in 5% and 32% of subjects (p < 0.001), and in 1% and 7% of systems applied (p < 0.001).
Conclusion: Scrotal systems produced no confirmed contact allergy and less topical irritation than nonscrotal systems. The four subjects with contact allergy to nonscrotal systems used the scrotal system without a reaction, suggesting testosterone was not the allergen.