Effect of dimethylthiourea on paraquat toxicity in rats.

We evaluated the utility of dimethylthiourea ( DMTU ), a hydroxyl radical scavenger, as potential therapy for paraquat poisoning. Seventy-five male Sprague-Dawley rats were divided into four groups ( DMTU -paraquat, paraquat, DMTU , control) and studied for up to 10 days. Clinical observations (dyspnea, weakness), mortality, hepatic and renal function tests, body weights, and histologic studies were performed. There was no mortality in the DMTU and control groups although various histologic and biochemical studies suggested that DMTU may be both hepatotoxic and nephrotoxic. In contrast, 74% of DMTU -paraquat rats and 39% of paraquat rats died (p less than 0.01). In addition, toxicity was clearly earlier in the DMTU -paraquat group than in the paraquat group. Hence, rather than being protective, treatment with dimethylthiourea was associated with increased mortality in paraquat-poisoned rats.