Phototoxicity profile of PUVA-oil bath therapy

Abstract

PUVA-bath therapy is a treatment modality of growing importance within dermatology. Compared with the commonly used oral application of psoralen, bath water delivery yields fewer adverse effects and therefore has been applied successfully in a wide range of dermatoses.1Hawk JL Grice PL The efficacy of localized PUVA therapy for chronic hand and foot dermatoses.Clin Exp Dermatol. 1994; 19: 479-482Crossref PubMed Scopus (32) Google Scholar, 2Kerscher M Volkenandt M Lehmann P Plewig G Röcken M PUVA-bath photochemotherapy of lichen planus.Arch Dermatol. 1995; 131: 1210-1211Crossref PubMed Scopus (42) Google Scholar, 3Lowe NJ Weingarten D Bourget T Moy PUVA therapy for psoriasis: comparison of oral and bath-water delivery of 8-methoxypsoralen.J Am Acad Dermatol. 1986; 14: 754-760Abstract Full Text PDF PubMed Scopus (151) Google Scholar, 4Schempp CM Müller H Czech W Schöpf E Simon JC Treatment of chronic palmoplantar eczema with local bath-PUVA therapy.J Am Acad Dermatol. 1997; 36: 733-737Abstract Full Text PDF PubMed Scopus (72) Google Scholar However, in many patients PUVA-bath therapy may lead to desiccation and pruritus of soaked skin areas. As oil baths are of great value in the treatment of dry skin,5Stender IM Blichmann C Serup J Effects of oil and water baths on the hydration state of the epidermis.Clin Exp Dermatol. 1990; 15: 206-209Crossref PubMed Scopus (26) Google Scholar we considered the combination of traditional PUVA-bath therapy with adjuvant bath oil (“PUVA–oil bath therapy”) a promising therapeutic alternative in patients with xerosis cutis receiving balneophotochemotherapy. To investigate whether the added bath oil changes the phototoxic response of the commonly used psoralen solution, we determined the minimal phototoxic UVA dose (MPD) in a randomized half-side study of 12 healthy volunteers (skin phototypes II-IV). Both forearms of each subject were immersed separately for 20 minutes in a dilute bath water solution each containing 1.0 mg/L of 8-methoxypsoralen (8-MOP) at 37°C. The 8-MOP solution on one side contained an adjuvant mineral bath oil in therapeutic concentration. The bath was directly followed by UVA administration of 0.5 to 3.0 J/cm2 on each volar aspect of the forearm. The MPD, defined as the smallest dose of UVA to result in a just-detectable erythema, was assessed visually at 72 hours after irradiation. Our results indicate that the MPD does not change significantly by adding mineral bath oil to the 8-MOP solution. The mean MPD in PUVA–oil bath was 1.58 J/cm2 (standard deviation, ± 0.67) and in commonly used PUVA-bath, 1.63 J/cm2 (standard deviation, ± 0.64). From these data it should be possible to simultaneously rehydrate the skin during balneophotochemotherapy with 8-MOP by adding a mineral bath oil product and through this accelerate the healing of the dermatosis. These data were supported by treating 2 patients with palmoplantar eczema. In a half-side test in these 2 patients, there was a slightly quicker clinical remission in the half treated with adjuvant bath oil in 8-MOP solution versus the half in 8-MOP solution alone. In this context it may be important to use a mineral bath oil because the unsaturated fatty acids of vegetable bath oils, such as soya oil, are known to be capable of filtering UV radiation (predominantly UVB, but also UVA), which may result in an unwanted increase in cumulative UVA doses. 16/8/102365 doi:10.1067/mjd.2000.102365