Immune responses to chlorpromazine in rats. Detection and relation to hepatotoxicity

It has frequently been suggested that the jaundice which occurs in a small percentage of human patients following treatment with chlorpromazine is due to a hypersensitivity reaction. It has, however, proved impossible to obtain an animal model for this condition. We now show that oral administration of chlorpromazine at 25 mg/kg per day to Wistar albino rats results in formation of both humoral and secretory antibodies to chlorpromazine. We also demonstrate that the severity of the hepatic changes observed in chlorpromazine-fed animals (periportal glycogen loss and centrilobular fatty change) is enhanced by preimmunization of the rats via the gut-associated lymphoid tissue with a chlorpramizine-protein conjugate. There was, however, no correlation between the titre of either serum or biliary antibodies in individual animals and the degree of liver damage. Our results therefore suggest than an immune mechanism is indeed implicated in chlorpromazine toxicity but show clearly that toxic symptoms are not a simple consequence of the formation of anti-chlorpromazine antibodies.