Abstract

In twin-control experiments, young, male albino rats were given intramuscular doses of chlorpromazine hydrochloride increasing from 1 mg per kg per day during the 1st week to 200 mg per kg per day during the 39th and 40th weeks. They developed tolerance to the sedative and lethal effects of chlorpromazine but no cross tolerance to pentobarbital hypnosis. Growth and fertility were impaired. Food and water intake and urine and stool output were normal or above normal per kg body weight. The animals developed alkaluria and indicanuria, hypochromic anemia and a leukocytosis, and no change in plasma lipid levels.

Abrupt withdrawal of chlorpromazine at the end of the 40th week was followed by hyperkinesia, diarrhea, and 2 deaths. The survivors began to grow and regained their sexual fertility by the 10th day. Food and water intake and stool output returned to normal in about 40 days. The anemia and leukocytosis were disappearing by the 21st day.