Ingestion of paraquat results in an extremely dangerous poisoning. The first aim is to clear the gastrointestinal tract by inducing emesis and performing gastric/gut lavage; as much activated charcoal as possible should be administered per os and as quickly as possible. The best measure to eliminate paraquat from blood and tissue is hemoperfusion with coated activated charcoal; it has to be performed in the sense of "continuous hemoperfusion" about 8 h/d over a period of 2-3 weeks. These measures give a chance to lower the lethality of paraquat poisoning.

In vitro investigations have shown that the adsorption capacity of activated charcoal ('Kohle-Compretten', 'Ultracarbon', E. Merck, Darmstadt, FRG) is just as high as that of 'Fuller's earth' (Surrey powder, Laporte Industries Ltd., Luton, GB) or 'Bentonite BP W.B. (Steetley Minerals Ltd., Milton Keynes, GB). Fuller's earth ('Fullererde') from another manufacturer has had very poor adsorption properties and is thus not suitable for the treatment of paraquat poisoning. Animal experiments have shown that the curative effect of activated charcoal given 0.5, 1, 2, and 3 h after ingestion of 200 and 300 mg paraquat/kg body weight is equally as good or even better than that of 'Fuller's earth' or 'Bentonite BP W.B' Activated charcoal is a substitute of equal value to these mineral soils.

An economical hemoperfusion system for clearance studies in vitro was developped. It was ascertained, that hemoperfusion using columns which contain 13 g of adsorbent and perfused at a blood flow rate of 1.25 ml/min results in the same relative clearances as when using clinical sized columns containing 300--355 g of the absorbent and run at 100ml/min. The adsorption kinetics of toxicologically important drugs and pesticides are given as examples. To date 27 substances were tested systematically. The investigation has shown, that no adsorbent is without exception the best one, but the efficacy can vary from substance to substance.