Haemoperfusion treatment in pigs experimentally intoxicated by paraquat

1. Because of their similarity in renal morphology and physiology to humans, domestic pigs (gilts, 70 kg) were bolus treated by intramuscular injection of 74, 17, and 6 mg kg-1 and by oral loading (70 mg kg-1 n = 4) of paraquat. The concentration peak of plasma paraquat was reached at 1.5 - 2.5 h. Renal clearance of paraquat rose to its maximum at 5-6 h after intoxication and then sharply decreased indicating renal failure. All the intoxicated pigs died. 2. An additional 10 gilts were also orally treated with 70 mg kg-1 paraquat but received haemoperfusion from 2 h post intoxication for either 2 h (n = 6) or 6 h (n = 4). The 2 h haemoperfusion resulted in a 5.1% toxin removal but failed to save any of six poisoned pigs. Prolonged 6 h haemoperfusion successfully rescued three out of four intoxicated pigs. 3. The plasma paraquat concentrations of the three surviving pigs were above 2 mg l-1 at 10 h post intoxication. This level is not only similar to those of untreated animals that died later, but also well beyond the suggested limit for survival of poisoned patients. 4. Pigs proved to be a good animal model for studies in paraquat poisoning and/or haemoperfusion. It is also suggested that early haemoperfusion is effective in treating paraquat poisoning even in very severe cases due to its possible detoxicating effect in addition to toxin removal.