Topical 8-methoxypsoralen enhances the therapeutic results of targeted narrowband ultraviolet B phototherapy for plaque-type psoriasis

Targeted broadband ultraviolet B (UVB) phototherapy as well as 308-nm excimer laser have been reported to significantly improve or clear localized psoriatic plaques within 5 to 10 treatments when medium fluences [i.e. 4-6 multiples of minimal erythema doses (MED)] were used. Our study was conducted to determine the effects of different concentrations of topical 8-methoxypsoralen (8-MOP) cream when used in combination with targeted UV phototherapy with regard to number of treatments and cumulative UV doses to clear localized psoriasis. Ten evaluable patients with stable plaque-type psoriasis completed the study. Three different concentrations of 8-MOP creams (0.001%, 0.01% and 0.1%) were applied prior to irradiation with 4 MEDs of targeted narrowband UVB (NB-UVB), whereas 0.001% 8-MOP cream was used in conjunction with 5 J/cm(2) UVA. All irradiations took place once weekly for 12 weeks. Psoriasis severity index (PSI) score was used to evaluate the efficacy of the treatment. With area-under-the-curve analysis, 0.1% 8-MOP/NB-UVB was superior to other modalities in reducing the PSI scores. The number of treatments and cumulative NB-UVB doses necessary to achieve PSI-95, a 95% reduction in the scores, was also lower in the 0.1% 8-MOP/NB-UVB group, although the differences were not statistically significant. We conclude that topical 8-MOP cream enhances the therapeutic effects of targeted NB-UVB phototherapy without significantly increasing the short-term adverse effects.