Fifty patients were enrolled in a double-blind, randomized, parallel-group study designed to determine whether tazarotene may have a role in maintenance therapy for psoriasis.
The patients had stable moderate-to-severe plaque psoriasis on up to 15% of their body surface area, on sites other than the face and scalp. Their mean age was 55 years and the majority had had psoriasis for more than 10 years. Washout periods were: 2 weeks for topical drugs, 4 weeks for UVB or PUVA treatment, and 8 weeks for systemic drugs that might alter the course of psoriasis.
For the initial open-label treatment phase, patients applied tazarotene 0.1% gel plus clobetasol propionate 0.05% ointment for 6 weeks. The frequency of application of both medications was initially once daily and then was tapered to ensure gradual weaning. Thus, during weeks 1 and 2, patients applied tazarotene each morning and clobetasol propionate each evening. During weeks 3 and 4, patients applied tazarotene each morning and clobetasol propionate each Tuesday, Thursday, and Saturday evening. Finally, during weeks 5 and 6, patients applied tazarotene each Monday, Wednesday, and Friday morning, and clobetasol propionate each Tuesday and Thursday evening.
For the subsequent double-blind maintenance phase, patients were randomized to receive one of three maintenance regimens for 20 weeks – tazarotene/clobetasol (tazarotene 0.1% gel on Monday, Wednesday, and Friday mornings, plus clobetasol propionate 0.05% ointment on Tuesday and Thursday evenings), tazarotene/vehicle (tazarotene 0.1% gel on Monday, Wednesday, and Friday mornings, plus white petrolatum on Tuesday and Thursday evenings), and vehicle (tazarotene gel vehicle on Monday, Wednesday, and Friday mornings plus white petrolatum on Tuesday and Thursday evenings).
Patients were instructed to apply a thin film of medication to their psoriatic plaques. Emollient use was permitted, but other topical formulations and excessive exposure to ultraviolet light were not.
Efficacy was evaluated – at baseline, every 2 weeks during the initial treatment phase, and every 4 weeks during the maintenance phase – in terms of overall disease severity, plaque elevation, scaling, erythema, pruritus, and global response to treatment. The first four of these were rated by the physician as 0 = none, 2 = mild, 4 = moderate, 6 = severe, and 8 = very severe. Pruritus was rated as 0 = none, 1 = trace, 2 = mild, 3 = moderate, 4 = marked, and 5 = severe. Global response was rated as 0 = cleared, 1 = almost cleared (∼90% improvement), 2 = marked (∼75%) improvement, 3 = moderate (∼50%) improvement, 4 = slight (∼25%) improvement, 5 = unchanged, and 6 = worse.
Analysis of variance and the Student's t-test were used to compare maintenance regimens (P ≤ 0.05). In the maintenance phase, the last recorded score for each patient was carried forward to all subsequent visits.