A randomized, double-blind, vehicle-controlled study of a novel liposomal dithranol formulation in psoriasis

Dithranol is infrequently used in psoriasis in spite of excellent efficacy due to its local adverse effects. We have synthesized a novel formulation of dithranol in which the drug is entrapped in phospholipid liposomes. This formulation has shown markedly low irritation and minimal staining of skin and clothes in preliminary studies. Twenty patients with bilaterally symmetrical stable plaque psoriasis applied 0.5% dithranol lipogel to lesions over one side of the body. On the other side, 10 patients were randomized to apply pure liposomal base and 10 applied a conventional cream containing 1.15% dithranol, 1.15% salicylic acid and 5.3% coal tar in a 30-minute, short contact regimen for 6 weeks. Patients were assessed for disease severity, perilesional erythema and skin staining, pruritus and any other adverse effects at baseline, 2, 4 and 6 weeks. Both lipogel and the cream significantly reduced the total severity score compared to the liposomal base at 4 (p = 0.004) and 6 (p = 0.01) weeks. There was no significant difference in the clinical response of dithranol cream and lipogel. Markedly low incidence and severity of perilesional erythema (p<0.001) and skin staining (p<0.05) was seen with the lipogel in comparison with the cream.