Paraquat is a widely used herbicide, known to cause lethal toxicity in humans. Most studies about paraquat have concentrated on systemic toxicity, however several cases of paraquat-induced dermatitis have been reported.

The purpose of this study was to confirm the cutaneous toxic effect of paraquat and to select potential antidotes in paraquat-induced dermatitis.

Keratinocyte toxicity due to paraquat and the toxicity reduction capacity of several drugs were investigated in eitro. Topical effects of these drugs on paraquat-induced dermatitis in guinea pig skin was also investigated.

Over 50% of keratinocytes failed to survive at a concentration of 2X10-4M paraquat by a neutral red uptake assay. Skin irritation by paraquat was observed at 2% concentration by non-invasive methods as well as a skin biopsy. Dexamethasone, glutathione and tocopherol showed some capacity to reduce paraquat-induced keratinocyte toxicity in vitro. Only dexamethasone, however, showed a reduction of cutaneous blood flow volume and dermal inflammatory cell infiltration in the guinea pig study.

This result indicates the possible in eitro protective effect of paraquat toxicity in glutathione and tocopherol. Dexamethasone was capable of reducing paraquat-induced cytotoxicity and dermatitis both in vitro and in vivo.