Halobetasol 0.01%/tazarotene 0.045% fixed-combination lotion in the treatment of plaque psoriasis: Sensitization and irritation potential

Background: Psoriasis is a chronic inflammatory skin disorder often managed with topical therapy. However, the most widely used treatments, including topical corticosteroids and tazarotene, can cause limiting skin irritation, contact sensitization, and/or present long-term safety concerns. Recently, clinical data on a new fixed combination of halobetasol 0.01%/tazarotene 0.045% (HP/TAZ) lotion were published. Objectives: We evaluated the results from two studies that assessed the potential for skin irritation (Study A) and contact sensitization (Study B) of HP/TAZ lotion. Methods: HP/TAZ lotion and vehicle were studied in 244 healthy volunteers for the potential to induce contact skin sensitization. An additional 21-day cumulative irritation study was performed in 40 healthy volunteers to compare HP/TAZ lotion, vehicle, tazarotene 0.05% (Tazorac®; Allergan, Dublin, Ireland) cream, and positive/negative controls. Cutaneous reactions at the application sites were evaluated in both studies clinically. Results: There was no evidence of contact sensitization, while the HP/TAZ lotion exhibited a low level of irritation in the induction phase. Mean cumulative irritation scores were 0.21 (HP/TAZ), 0.07 (vehicle), and 0.04 (saline). In the separate 21-day irritation study, mean cumulative irritation scores were 0.36 (HP/TAZ), 0.56 (tazarotene), 0.03 (vehicle), 0.23 (sodium lauryl sulfate), and 0.04 (saline), while mean total irritation scores were 7.55 (HP/TAZ), 11.60 (tazarotene, p=0.0013 versus HP/TAZ), 0.63 (vehicle), 4.73 (sodium lauryl sulfate), and 0.88 (saline). HP/TAZ was “slightly irritating” but significantly less so than tazarotene (p=0.0009). Conclusion: HP/TAZ lotion caused only minimal skin irritation. It was significantly less irritating than tazarotene cream.