Appearance of intoxication in rats by intraperitoneal administration of clioquinol

The investigation was undertaken to study the neurological symptoms in rats caused by maintaining high plasma concentration of about 30 nmol/ml or more, of clioquinol. Clioquinol suspension which was prepared using polysorbate 80 was administered intraperitoneally to rats and plasma and tissue concentrations were determined. On administration of clioquinol of 100 and 200 mg/kg, the mean plasma concentrations of clioquinol reached maximum values of 30 and 58 nmol/ml, respectively, after 0.5-1 h and thereafter decreased rapidly. With 400 mg/kg, however, plasma concentration reached maximum value of about 75 nmol/ml and fell slowly. By single and repeated administration of the suspension, clioquinol was distributed in the liver and kidney at a high concentration, and also in the nervous system. In experiments on appearance of neurotoxicity in rats by repeated administration of the suspension, all of 10 rats administered intraperitoneally with 100 mg/kg/d did not develop any neurological symptoms for about 30 d. On the other hand, one of 10 and 7 of 13 rats administered with 200 and 400 mg/kg/d, respectively, developed ataxia in the hind legs or all legs on the 3rd to the 12th day after starting administration. Pathologically, a slight change of the peripheral nerve, central chromatolysis of the anterior horn neuron and severe neuronal degeneration of the Ammon's horn were observed in the rats with ataxia.