In vivo toxicity and pulmonary effects of promazine and chlorpromazine in rats

Abstract Cationic amphiphilic drugs induce a phospholipid storage disorder known as phospho‐lipidosis. Halogenated analogs of the drugs are more potent inducers of phospholipidosis when compared to nonhalogenated analogs. Two such antipsychotic drugs, promazine and chlorpromazine, are effectively taken up by the lungs and induce lamellar inclusions in vitro. We compared the in vivo toxicity and efficacy of promazine and chlorpromazine to induce phospholipidosis in the lung and in pulmonary alveolar macrophages. Male Sprague‐Dawley rats were given promazine or chlorpromazine (25 mg/kg/day, P.O., in water) for 5 weeks. Food intake was decreased in promazine‐ and chlorpromazine‐treated rats, chlorpromazine rats being affected more than promazine rats. To minimize experimental error due to starvation, control rats were pair‐fed. The body weight gain was decreased in chlorpromazine rats in comparison to pair‐fed controls. Chlorpromazine‐treated rats, but not promazine‐treated rats, showed increased mortality over the 5‐week treatment period. Histopathologic examination of lung revealed loss of alveolar macrophages with no other gross abnormalities in chlorpromazine‐treated rats. Quantitative analysis of lung lavage also showed significant reduction in the number of macrophages. This finding is in contrast to other cationic amphiphilic drugs, which induce phospholipidosis as well as accumulation of alveolar macrophages. Phospholipid level increased in alveolar macrophages but not in lavaged lung following chlorpromazine treatment. Acid phos‐phatase activity in lavaged lung homogenate and macrophages of promazine‐ and chlorpromazine‐treated rats,taken as an index of toxicity to cells, did not differ significantly from control rats. In vivo binding of promazine and chlorpromazine to the lamellar bodies isolated from lungs was quantitated using 1,6‐diphenyl‐1,3,5‐hexatriene and 1‐anilino‐8‐naphthalene sulfonate as fluorescence probes for hydrophobic and hydrophilic moieties, respectively. 1,6‐Diphenyl‐1,3,5‐hexatriene or 1‐anilino‐8‐naph‐thalene sulfonate fluorescence with lamellar bodies did not differ in control, promazine‐, or chlorpromazine‐treated rats, indicating that sufficient drug was not bound to lamellar bodies to be sensitive enough to detect using fluorescence probes. Thin‐layer chro‐matography identification of these drugs from lung extract revealed no detectable spots against the authentic drug standards indicating that promazine and chlorpromazine may not accumulate significantly in the lung in vivo to be detected by thin‐layer chromatography. These results indicate that chlorpromazine is more toxic to rats than promazine and decreases the alveolar macrophages, suggesting that macrophages are the targets of chlorpromazine‐in‐duced phospholipidosis. Long‐term chlorpromazine and promazine treatment may lead to phospholipidosis in alveolar macrophages, which can be a sensitive indicator of this disorder.