TOPICAL TRETINOIN (RETINOIC ACID) IMPROVES MELASMA - A VEHICLE-CONTROLLED, CLINICAL-TRIAL

Melasma is a common disorder of cutaneous hyperpigmentation predominan tly affecting the faces of women. Little is known about the aetiology of melasma, and treatment is frequently disappointing. Topical tretino in is of benefit in treating other forms of hyperpigmentation, for exa mple liver spots, and we therefore investigated its effectiveness in m elasma. Thirty-eight women completed a randomized, vehicle-controlled study, in which they applied 0.1% tretinoin (n = 19) or vehicle cream (n = 19) once daily to the face for 40 weeks. At the end of treatment 13 (68%) of 19 tretinoin-treated patients were clinically rated as imp roved or much improved, compared with 1 (5%) of 19 in the vehicle grou p (P = 0.0006). Significant improvement first occurred after 24 weeks of tretinoin treatment. Colorimetry (an objective measure of skin colo ur) demonstrated a 0.9 unit lightening of tretinoin-treated melasma an d a 0.3 unit darkening with vehicle (P = 0.01); these results correlat ed with clinical lightening (r = 0.55, P = 0.0005). Histologically, ep idermal pigment was reduced 36% following tretinoin treatment, compare d with a 50% increase with vehicle (P = 0.002). Reduction in epidermal pigment also correlated with clinical lightening (r = -0.41, P = 0.01 ). Moderate cutaneous side-effects of erythema and desquamation occurr ed in 88% of tretinoin-treated and 29% of vehicle-treated patients. To pical 0.1% tretinoin produces significant clinical improvement of mela sma, mainly due to reduction in epidermal pigment, but improvement is slow.