Cutaneous tolerability to tretinoin shows little variation with Fitzpatrick skin type.

Determinants of skin irritability are poorly understood. This study aims to assess differences in cutaneous safety/irritation based on Fitzpatrick skin type among patients with acne treated with tretinoin gel microsphere (TGM). This was a phase 4, 12-week, prospective, nonrandomized, open-label, multicenter study. Approximately 500 patients with mild to moderate acne were treated with TGM 0.04% or 0.1% and assessed for cutaneous irritation at baseline and weeks 3, 6, and 12. In this post hoc analysis of patients with Fitzpatrick skin type I-III vs Fitzpatrick skin type IV-VI, there was a general trend toward initial worsening of cutaneous adverse events (AEs) by week 3 across all variables and groups. This was followed by a trend toward improvement and resolution of skin-related AEs from week 3 to week 12 regardless of Fitzpatrick skin type, with a few exceptions. Erythema was the only cutaneous AE that consistently decreased among patients with darker skin. Results from a subsequent 3-group analysis (Fitzpatrick I-II vs Fitzpatrick III-IV vs Fitzpatrick V-VI) generally mirrored those from the 2-group study. Study limitations include patient nonadherence, lack of a placebo arm, and lack of data regarding the impact of concurrent medications on outcomes. There was no correlation between irritation and Fitzpatrick skin type. ABBREVIATIONS USED: adverse event (AE), analysis of variance (ANOVA), benzoyl peroxide (BP), case report form (CRF), modified Global Acne Grading Score (mGAGS), tretinoin gel microsphere (TGM).