PHOTOPROTECTIVE ACTION OF EMOLLIENTS IN ULTRAVIOLET THERAPY OF PSORIASIS

An in vitro technique was used to measure the monochromatic protection factors of all emollients available on prescription. The action spect ra for ultraviolet erythema and erythema in psoralen-sensitized skin w ere used to calculate, for each emollient, erythema protection factors relevant to UVB phototherapy and psoralen photochemotherapy, respecti vely. Of the 40 products tested, 22 (55%) had a UVB erythema protectio n factor >1.2 at an application density of 2 mu l/cm(2), and 31 (78%) at an application density of 4 mu l/cm(2). Fewer products, 25% at 2 mu l/cm(2) and 50% at 4 mu l/cm(2), had a psoralen erythema protection f actor >1.2. A protection factor of 1.2 is equivalent to a reduction in ultraviolet dose of 17%, and is thus likely to be of clinical importa nce. These results allow a choice of emollient products which may impr ove response by increasing transmission of radiation through psoriasis scale without a concomitant decrease in transmission due to a sunscre ening action.