A fixed-dose combination lotion comprised of halobetasol propionate 0.01% and tazarotene 0.045% (HP/TAZ) is more effective for treating moderate-to-severe plaque psoriasis than either component alone, researchers found. The findings from this study were published in the Journal of Drugs and Dermatology.

A total of 212 patients with moderate-to-severe plaque psoriasis were randomly assigned 2:2:2:1 to receive either once-daily HP/TAZ lotion, HP alone, TAZ alone, or vehicle for 8 weeks. The researchers compared groups in terms of treatment efficacy, defined as the proportion of patients who achieved ≥2-grade improvement in the Investigator Global Assessment (IGA) and IGA score equal to “clear” or “almost clear,” as well as the percent change from baseline in the IGAx body surface area (BSA) score. Patients who achieved a 75% reduction in the IGAxBSA were deemed to have experienced a clinically meaningful outcome.

Synergy, defined as the “benefit of combination HP/TAZ lotion treatment — benefit of HP plus benefit of TAZ, where the ratio of HP/TAZ divided by HP+TAZ > 1,” was identified at week 8 for the HP/TAZ combination lotion as well as 4 weeks after treatment.

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At 8 weeks of treatment, the treatment efficacy of HP/TAZ was 42.8% relative to vehicle vs 32.5% for HP plus TAZ compared with vehicle (ratio, 1.3). The percent change from baseline in the IGAxBSA score compared with vehicle was higher in the HP/TAZ lotion vs the HP plus TAZ group (51.6% vs 40.6%, respectively). Treatment success was similarly higher at 12 weeks for the combination lotion vs the HP plus TAZ constituents relative to vehicle (31.3% vs 20%, respectively). In addition, HP/TAZ combination was associated with a higher percent change from baseline in the IGAxBSA score relative to vehicle (47.3% vs 34.2%).

Limitations of the study include the limited follow-up duration as well as the study’s relatively small sample size.

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“It is uncertain why HP/TAZ lotion confers better efficacy than the constituent parts, but it may be due to a synergistic anti-inflammatory effect,” the researchers explained. “The use of topical corticosteroids, such as halobetasol is commonplace in psoriasis, mainly due to their immunosuppressive, anti-inflammatory, and anti-proliferative properties.”

Disclosures: Drs Kircik, Papp, and Gold report multiple relationships with Ortho Dermatologics. Additionally, Dr Gold reports relationships with Leo, Novartis, and Celgene. Drs Harris, Lin, and Pillai are employees of Bausch Health.


Kircik LH, Papp KA, Stein Gold L, Harris S, Lin T, Pillai R. Assessing the synergistic effect of a fixed combination halobetasol propionate 0.01% and tazarotene 0.045% lotion in moderate-to-severe plaque psoriasis. J Drugs Dermatol. 2019;18(3):279-284.

This article originally appeared on Dermatology Advisor