Predictive animal testing for photocontact allergenicity

Abstract

The purpose of this investigation was to establish a standardized animal model to predict the photoallergenic potential of new chemical compounds. In a first series of experiments the main factors influencing the induction of photoallergenicity were evaluated (induction concentration, pH of the test solution, pretreatment of the irradiation site with sodium lauryl sulphate, additional use of adjuvant injections and routes of administration). Osram Ultravitalux lamps were utilized for these studies. In a second series of experiments a Xenon 6000 W radiation source was used. Positive results were obtained with well known photosensitizers, as, for instance, the halogenated salicylanilides, as well as with so-called weak photoallergens (e.g. bithionol, sulphanilamide) by stimulating the animals' immune system with Freund's complete adjuvant. The photoallergenic compounds were at the same time tested for their contact allergenic potential in the optimization test. A standard procedure for the predictive photoallergenicity assay in guinea-pigs is proposed.

A qauntitative in vitro assay for the evaluation of phototoxic potential of topically applied materials

“…Positive responses elicited by three of the fragrances could not be demonstrated at 50% concentration in the animal assay. Several publications have documented the photoallergic properties of tribromosalicylanilide and tetrachlorosalicylanilide (Maurer et al, 1980;Vinson et al, 1966;Harber et al, 1966). These materials demonstrated in vitro antimicrobial properties and were negative in the guinea pig phototoxic test.…”

Bithionol [MAK Value Documentation, 1998]

“…In another study with 19 guinea pigs after induction in the light, no positive reactions were seen after the first provocation (0.1 % intradermal) and only 3 positive reactions after the second (1 % epicutaneous, occlusive); these results indicate a minimal potential for contact sensitization (Maurer et al 1980). …”

“…Bithionol is classified as a weak contact photoallergen (Guillot et al 1985, Horio 1976, Maurer et al 1980, Miyachi and Takigawa 1983, Morikawa et al 1974b, Unkovic et al 1988. n.s.…”

Sensitization of mice to topically applied drugs: albuterol chlorpheniramine, clonidine and nadolol

“…Guinea pigs have generally been used to study allergic contact dermatitis from weak and moderate sensitizers, since they are easier to sensitize than· mice (7). However, 3 techniques have been reported for improving the response of mice to con-tact allergens.…”