A clinical trial of topical bleaching treatment with nanoscale tretinoin particles and hydroquinone for hyperpigmented skin lesions

BACKGROUND Although combined use of tretinoin (all-trans-retinoic acid; atRA) and hydroquinone improves various hyperpigmented lesions, the pharmacologic instability of atRA and atRA-induced irritant dermatitis are difficult unsolved problems. OBJECTIVE The objective was to evaluate the efficacy and adverse effects of a newly formulated gel containing inorganic-coated atRA nanoscale particles (nano-atRA gel). METHODS Nano-atRA gel was used in our two-phased bleaching protocol: 5% hydroquinone and 7% lactic acid ointment were used along with nano-atRA gel in the bleaching phase (2-8 weeks), and 5% hydroquinone and 7% ascorbic acid ointment were used alone during the healing phase (4-8 weeks). Eighty-four patients with facial hyperpigmented lesions were enrolled in this study, and 77 of them (88 lesions) followed up for more than 10 weeks were analyzed. RESULTS Hyperpigmentation was improved in 84 of 88 lesions (95.5%) after a mean treatment period of 14.3 weeks and was almost eliminated in 52 lesions (59.1%). Nano-atRA gel caused exfoliation and scaling similar to that seen with conventional atRA gel, whereas the erythema seen in the bleaching phase appeared to be weaker. CONCLUSION Nano-atRA gel can improve hyperpigmentation to a similar extent as conventional atRA gel. It also induces irritant dermatitis, but with less erythema.