Why Topical Retinoids Are Mainstay of Therapy for Acne
The facial tolerability of various topical retinoids was evaluated in 253 healthy volunteers in a series of split-face, randomized, investigator-masked studies-all conducted at the same site by the same investigator. Four variables were evaluated to determine if they influenced tolerability-retinoid concentration, formulation vehicle, skin sensitivity, and individual retinoid. Lower retinoid concentrations were associated with less irritation. Vehicle influenced tolerability but whether a gel or cream formulation was better tolerated varied from retinoid to retinoid. Tolerability was superior on normal skin than "sensitive skin." On normal skin, tazarotene cream was better tolerated than tretinoin cream whereas adapalene and tretinoin microsponge gels were better tolerated than tazarotene gel. On sensitive skin, tazarotene and adapalene creams were better tolerated than tretinoin cream whereas adapalene gel was better tolerated than tazarotene gel. Retinoid concentration, vehicle, skin sensitivity, and retinoid can all affect facial tolerability. Skin vulnerability may be the most important factor.