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The relationship between plasma psoralen concentration and psoralen‐UVA erythema
Author(s) -
MCLELLAND JANET,
FISHER CHRISTINE,
FARR P. M.,
DIFFEY B. L.,
COX N. H.
Publication year - 1991
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/j.1365-2133.1991.tb04956.x
Subject(s) - psoralen , erythema , puva therapy , plasma concentration , chemistry , dose–response relationship , positive correlation , methoxsalen , body weight , medicine , psoriasis , dermatology , biochemistry , dna
Summary The plasma 8‐methoxypsoralen (8‐MOP) concentration was measured in 60 patients commencing psoralen photochemotherapy (PUVA). At the time of blood sampling each patient was phototested using a series of 10 exposures to UVA. The resulting erythema was measured objectively 72 h after irradiation and dose‐response curves for psoralen‐UVA erythema were constructed. Although the dose of 8‐MOP was calculated according to body weight, patients receiving 30 mg of 8‐MOP had a significantly lower mean plasma concentration than those receiving higher doses. There was no significant correlation between plasma 8‐MOP concentration and minimal phototoxic dose, either estimated visually or calculated from the dose‐response curves. However the slope of the dose‐response curve showed significant correlation with plasma 8‐MOP concentration. The variation between patients in the rate of increase of the erythemal response, but not the variation in threshold sensitivity, can be explained by differences in plasma psoralen concentration.