Instrumental evaluation of retinoid-induced skin irritation

Retinoids like tazarotene are approved for the treatment of chronic plaque psoriasis. In the beginning of topical retinoid therapy, 15-20% of the patients suffer from mild to moderate adverse reactions with burning and erythema. The aim of the study was to find predicative parameters of the individual irritative potential and to suggest options to reduce these initial irritations.

Twenty in-patients with different skin types (1 + 2: 11, 3 + 4: 9), with chronic plaque psoriasis were included in this open study. In each patient, 7 randomized plaques on the forearm were treated for 14 days on different ways: test area 1: morning (m) and evening (e) placebo, test area 2: placebo (m) and tazarotene 0.05% (e), test area 3: placebo (m) and tazarotene 0.1% (e), test area 4: calcipotriol (m) and calcípotriol (e), test area 5: mometasone furoate (m) and tazarotene 0.05% (e), test area 6: mometasone furoate (m) and tazarotene 0,1% (e), test area 7: placebo (m) and tazarotene in increasing concentrations (e), test area 8: healthy skin for control. Before and after therapy, skin barrier function, blood flow and plaque thickness in 20-MHz sonography were assessed in different test areas intraindividually by non- invasive biophysical measurements.

After 14 days of therapy, tazarotene 0.05% and 0.1% produced a stronger increase of laser Doppler flow in patients with skin type 1 and 2 than in patients with skin type 3 and 4. When using the combination therapy of tazarotene and mometasone, the laser Doppler flow was significantly lower than in tazarotene as monotherapy. 20-MHz-ultrasound showed a significant decrease in the thickness of the echo-poor band in all topical therapy regimens compared to placebo. Patients of skin type 1 and 2 reached a higher density of the dermis than patients of skin type 3 and 4, meaning a stronger decrease of inflammatory infiltration and acanthosis.

Adapting retinoid therapy to the patient's skin type can reduce the initial irritative side-effects. During the first days, patients with skin type 1 or 2 should add a medium potency corticosteroid. Stronger skin irritation caused by tazarotene therapy increases therapy effects.