Effects of prolonged administration of chlorphentermine on the rat lung.

Prolonged administration of the anorexigen chlorphentermine hydrochloride to young male Wistar albino rats for up to one year failed to induce in them either right ventricular hypertrophy or hypertensive pulmonary vascular disease. There was, however, the development of a pronounced pulmonary histiocytosis. Studies by light and electron microscopy showed that these histiocytes disintegrated to liberate their lamellar inclusions into the alveolar spaces, producing a picture reminiscent of alveolar proteinosis. Fibrosing alveolitis occurred in only one animal and was thought to be related to inflammatory changes rather than as a development of the pulmonary histiocytosis. Attention is drawn to the fact that thick-walled large pulmonary arteries are entirely normal in rats and should not be misinterpreted as evidence of hypertensive pulmonary vascular disease in test animals.