INTRODUCTION
Scalp psoriasis is a common psoriatic manifestation that negatively affects hair growth and appearance, as well as quality of life.1-3 Up to 80% of patients with psoriatic disease have scalp involvement, which is characterized by distressing symptoms, including itching and scaling.4 Scale is commonly shed as dandruff and can be a source of embarrassment for affected patients, especially in social settings.5
Itch is the most commonly reported symptom of scalp disease and elicits scratching that can cause painful wounds and permanent hair damage.6-8 Excessive scalp scratching is associated with hair breakage.9 Approximately 45 minutes of scratching (often accumulated over a 1- to 2-week period in the authors' clinical experience) can remove the entire cuticle, thus weakening the hair shaft and leading to hair breakage.10 Frequent scratching of the scalp can also lead to koebnerization and hyperkeratotic lesions, which may resist therapy, further hindering disease control.7 Additionally, long-lasting psoriatic lesions may cause scarring alopecia.11 Overall, hair loss or damage resulting from scalp psoriasis can lower self-esteem and cause substantial emotional distress.5
Topical therapies are currently recommended as first-line treatment for scalp psoriasis, and current formulations include shampoos, gels, oils, and foams12; however, challenges exist with current topical therapies. The presence of hair and thick, treatment-resistant hyperkeratotic plaques may impair the application and penetration of topicals, leading to reduced treatment efficacy.5,13 Adherence to topical therapy is also challenging because of patient dissatisfaction with vehicle formulations, which may be greasy and difficult to apply and remove from hair. Alternatively, formulations with high alcohol content often cause dryness or stinging; as such, a lotion-based formulation that is hydrating but nongreasy may be more suitable for patients with scalp psoriasis.14 Further, topical therapies are needed that are efficacious for all areas of the body, including the scalp, because they may reduce treatment complexity and improve patient adherence.15
Fixed-combination halobetasol propionate (0.01%) and tazarotene (0.045%) lotion (HP/TAZ) is indicated for the topical treatment of plaque psoriasis in adults.16 The efficacy and safety of HP/TAZ in plaque psoriasis have been demonstrated in 2 phase 3 trials and a 52-week open-label study, but scalp psoriasis was not included in these trials.17,18 Of note, the vehicle lotion of HP/TAZ may be suitable for application to hair-bearing areas such as the scalp because of its hydrating, mesh matrix formulation, which contributes to even and rapid penetration of active compounds.19 Previously, the lotion formulation of HP/TAZ was rated by greater than or equal to 93% of healthy volunteers (N=15) as more hydrating, lightweight, and moisturizing than their current lotion in a patient perception evaluation.19 These properties of HP/TAZ, coupled with its demonstrated efficacy in plaque
