title: Improved prediction of the minimal phototoxic dose in PUVA therapy.
abstract: In an attempt to improve the prediction of PUVA erythemal sensitivity, we have examined, in 251 patients, the relationship between the minimal phototoxic dose (MPD) and a number of variables, including skin type, ingested dose of 8-methoxypsoralen (8-MOP) and history of previous PUVA treatment. The MPD was determined by phototesting 2 h after ingestion of crystalline 8-MOP, given at a standard dose of 0.6 mg/kg (calculated to the nearest 10 mg). No reaction to the highest dose of UVA used for phototesting occurred in 16% of cases; the dose of 8-MOP was significantly associated with non-response. In the patients in whom an erythemal response was obtained, a significant association was found between the MPD and the variables of skin type, ingested dose of 8-MOP, and history of previous PUVA treatment. Thus, by taking these factors into account, a more accurate prediction can be made of an individual patient's erythemal sensitivity to PUVA than relying on skin type alone. That erythemal sensitivity is affected by the ingested dose of 8-MOP (even when all patients received 0.6 mg/kg) suggests that conventional psoralen dosing according to body weight is not ideal.
authors.affiliation: Department of Dermatology, Royal Victoria Infirmary, Newcastle upon Tyne, U.K.
authors.forename: A
authors.initials: A
authors.lastname: Sakuntabhai
authors.forename: J N
authors.initials: JN
authors.lastname: Matthews
authors.forename: P M
authors.initials: PM
authors.lastname: Farr
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017484:Dermatitis, Phototoxic / Q000209:etiology* / Q000473:pathology; D004334:Drug Administration Schedule; D005127:Eye Color; D005260:Female; D006200:Hair Color; D006801:Humans; D008297:Male; D008730:Methoxsalen / Q000008:administration & dosage; D008875:Middle Aged; D011701:PUVA Therapy / Q000009:adverse effects*; D012867:Skin / Q000473:pathology / Q000528:radiation effects
chemical_list: D008730:Methoxsalen