A Reappraisal of Fixed-Combination Halobetasol Propionate and Tazarotene for the Treatment of Psoriasis: Biological Underpinnings, Therapeutic Mechanisms, and Economic Considerations

Psoriasis is a complex inflammatory disease, which can be triggered by the interplay among keratinocytes, various immune cells, and even dermal vascular endothelial cells. Understanding of the key players and cytokine/chemokine messengers involved in the initiation and maintenance of psoriasis has significantly evolved and led to numerous systemic biologic therapies targeting those specific components. These therapies, despite their successes, do not ubiquitously affect all pathogenic cellular pathways. They also carry their risks and may be contraindicated in certain patient populations. Therefore, other therapeutics are still necessary. Tazarotene, a decades-old topical retinoid, has been successfully used for treating cutaneous psoriasis. Its retinoid effect via binding to retinoic acid receptors (RAR)/retinoic X receptors (RXR) alters cellular gene expression of numerous pathogenic cells and leads to a long-standing maintenance effect despite discontinuation. a phenomenon known as remittance. Concurrent use of tazarotene with topical corticosteroids results in reduced incidence of treatmentrelated adverse events. A fixed-combination lotion containing halobetasol propionate (HP) and tazarotene (HP 0.01%/TAZ 0.045%, Duobrii, Ortho Dermatologics) was developed implementing polymeric emulsion technology that demonstrates efficacy in psoriasis while mitigating adverse events associated with each component alone as monotherapy. In this paper, we review the pathogenesis of psoriasis and illuminate the effect of tazarotene and HP on key cellular pathways. In addition, we review the clinical efficacy of fixed-combination HP 0.01 %/TAZ 0.045% lotion in psoriasis as well as its long-term treatment maintenance, applicability in skin of color, and beneficial economic impact for patients and healthcare stakeholders. As HP 0.01 %/TAZ 0.045% lotion is safe and exhibits excellent efficacy, it should be within the therapeutic toolbox for every psoriasis patient.