Background and objective: The therapeutic efficacy of the tretinoin products Tretin-X (Triax Pharmaceuticals, Cranford, NJ) and Retin-A (Johnson & Johnson, New Brunswick, NJ) in the treatment of acne vulgaris was compared in four bioequivalence studies.
Methods: Four double-blind, three-treatment, parallel-group studies randomly assigned 1642 adolescents and adults, 12-40 years of age, with mild-to-severe acne vulgaris to receive topical tretinoin therapy with Tretin-X, Retin-A, or placebo (drug vehicle) as 0.1% cream (study 1), 0.025% cream (study 2), 0.025% gel (study 3), and 0.01% gel (study 4) once daily for 84 days. The primary efficacy measures were overall acne severity and the number of inflammatory lesions. The secondary efficacy measure was the total number of lesions.
Results: In each trial, Tretin-X and Retin-A were clinically equivalent according to all primary and secondary end points at Weeks 2, 4, 8, and 12, a finding also demonstrated by the averaged scores from Weeks 2 through 12. Moreover, each active treatment was significantly more efficacious than placebo at the conclusion of the study (p<or=0.05). Both of the Tretin-X and Retin-A formulations compared in each study were well tolerated. The severity of erythema and peeling did not differ significantly among the three groups studied.
Conclusions: The four bioequivalence studies demonstrated that Tretin-X and Retin-A tretinoin products behaved similarly in patients with mild-to-severe acne vulgaris and were thus clinically bioequivalent. Both treatments were well tolerated, and their associated adverse events were similar to those with placebo.