Sunscreens' photochemical behaviour: in vivo evaluation by the stripping method.

This study shows the influence of a water-in-oil emulsion and an oil-in-water emulsion on the photochemical behaviour of four sunscreen preparations containing various amounts of three UV filters: octyl methoxycinnamate, butyl methoxydibenzoylmethane, and 4-methylbenzylidene camphor. With the stripping method in vivo, skin-product interactions were evaluated after topical application and ultra-violet exposure. Evaluations were also made under the same operating conditions as in determining sun protection factor in vivo. Results showed that each sunscreen preparation has a particular photochemical behaviour related to filter mixture and emulsion type. When developing a sunscreen preparation the choice of the emulsion type and filters is relevant for achieving optimum efficacy and spectral stability.

Variation in 8-methoxypsoralen profiles during long-term psoralen plus ultraviolet A therapy and correlations between serum 8-methoxypsoralen levels and chromametric parameters.

Three serum 8-methoxypsoralen (8-MOP) kinetics tests were performed on 15 patients undergoing PUVA therapy. The first test was carried out before beginning PUVA treatment, the 2nd one at the 10th session and the 3rd test at the 20th PUVA session. Blood samples were taken every 30 min after the drug was taken and a standard meal ingestion during 3 h to determine the serum 8-MOP peak level and corresponding time. For 14 patients, UVA-induced erythema was measured with a Minolta CR 200 chromameter, 3 (before beginning PUVA treatment, just before 10th session and 48 h later) or 5 times (before beginning PUVA treatment, just before 10th session and 48 h later, just before 20th session and 48 h later). There was a wider distribution of serum 8-MOP peak levels in the 3rd test than in 2nd one and in the 2nd one than in the first one. These facts suggest a heterogeneity in 8-MOP metabolism in the 15 patients: 11 patients showed an earlier serum 8-MOP peak and an earlier appearance of the drug in blood in the 3rd and 2nd test than in the first one. For 9 of these 11 patients, serum 8-MOP peak levels were higher and higher from the first profile to the 3rd one, suggesting an inhibition of 8-MOP metabolism in time. In the remaining 4 patients, the 8-MOP peak time and the appearance of the drug in blood were delayed in the 3rd test compared with the first profile.(ABSTRACT TRUNCATED AT 250 WORDS)

[Is accurate UVA dosimetry in photobiology and photodermatology an illusion?]. / Une dosimétrie UVA précise en photobiologie et en photodermatologie est-elle une illusion?

Accurate UVA dosimetry is of primary importance for photobiological research as well as for UVA phototherapy and photochemotherapy. For the former, it is necessary because the success or failure of an experiment can depend on the UVA dose, and for the latter, the carcinogenic risks are dependent upon the cumulative dosage, as is the evaluation of the therapy. Experience has shown that the UVA meters used in different photodermatological and photobiological centers give divergent values when exposed to the same UVA source. One Joule/cm2 does not seem to be the same thing everywhere, and it can vary by as much as 400 p. 100.