Psoriasis affects approximately 2% to 3% of the US population and is characterized by plaques that are red, scaly, and elevated.1 Cutaneous symptoms of the disease are described by patients as itching, burning, and stinging sensations. Large multinational and US surveys have reported pruritus as patients’ most bothersome symptom, with scaling/flaking reported as the second most bothersome.2,3 Reported incidence rates for itching range from 60.4% to 98.3%, with at least half of these patients reporting daily or constant pruritus.2,4-7 Consequent effects on quality of life include impaired sleep,6 difficulty concentrating, lower sex drive, and depression.7 Despite these findings, pruritus is rarely included in the efficacy assessments of psoriasis treatments. In addition, 2 of the most commonly reported but difficult-to-treat locations for plaques are the outside of the elbows (45%) and the knees (32%),1,2,8 areas where the stratum corneum typically is thicker, less hydrated, and less likely to absorb topical products.9-11 Clinical studies have not focused specifically on these areas when assessing treatments.
Topical corticosteroids have been the mainstay of psoriasis therapy for decades because of their anti-inflammatory and antiproliferative properties.7 One large multinational physician survey indicated that 75% of patients are prescribed topical steroids,12 which are important for first-line treatment and are often maintained as adjunctive therapy in combination with other treatments for patients with extensive disease or recalcitrant lesions.13 Topical corticosteroids are ranked into different classes based on their vasoconstrictor assay (VCA), a measure of skin blanching used as a marker for vasoconstriction. Topical agents with VCA ratings of mid-potency or superpotency are generally recommended for initial therapy, with superpotent agents required for the treatment of thick chronic plaques. However, longer durations of use may contribute to systemic absorption and adverse events.13 The vehicle composition is important for corticosteroid delivery and retention at the site of pathology, contributing to the efficacy of the steroid.13,14 Selecting the appropriate steroid and vehicle is important to maximize efficacy and minimize adverse events.
Betamethasone dipropionate (BD) spray 0.05% is an emollient formulation of 0.05% BD that can be sprayed onto psoriatic plaques. The BD spray formulation was designed to penetrate the stratum corneum and be retained within the dermis and epidermis, the site of T-cell activity that drives the psoriatic disease process.14 In 2 phase 3 studies, BD spray demonstrated the ability to reduce the signs of plaque psoriasis with indication of improvement by day 4.15,16 These studies also showed improvement in the local cutaneous symptoms of itching, burning and stinging, and pain. As a mid-potent steroid, BD spray displays less systemic absorption but similar efficacy compared to a superpotent augmented BD (AugBD) lotion in relieving the signs and symptoms of plaque psoriasis.15-17
The objective of the current investigation was to assess the ability of BD spray to relieve itching and to clear plaque psoriasis on the knees and elbows utilizing post hoc analyses of the 2 phase 3 trials. The goal of these analyses was to demonstrate BD spray as effective at relieving the most troublesome signs and symptoms affecting patients with plaque psoriasis.
Two phase 3 studies were conducted to demonstrate the efficacy and safety of BD spray.15,16 The design of the studies was similar15,16 to allow the data to be pooled for post hoc analyses.
Both were US multicenter, randomized, vehicle-controlled, double-blind, parallel-group studies comparing the safety and efficacy of BD spray 0.05% (Sernivo, Promius Pharma) with its vehicle formulation spray (identical to BD spray, but lacking the active steroid component).15,16 One of the studies also compared BD spray with an AugBD lotion 0.05% (Diprolene,Merck & Co). Adults with moderate plaque psoriasis (investigator global assessment of 3; 10%–20% body surface area) were randomized to apply BD spray, vehicle spray, or AugBD lotion (1 study only) twice daily to all affected areas, excluding the face, scalp, and intertriginous areas for 28 days (BD spray and vehicle) or 14 days (AugBD lotion, per product label).15