Pulmonary absorption of drugs in the dog: comparison with other species.

To investigate the pulmonary absorption rate of drugs in the anesthetized beagle dog, 5 ml of drug solution was administered into the lungs by rapid injection through a tracheal cannula. After various times, lungs were removed and assayed for unabsorbed drug. The dog absorbed lipid-insoluble drugs such as p-aminohippuric acid, mannitol, and procainamide ethobromide at the same rate as the rat, two times more rapidly than the rabbit, and approximately 2-3 times more slowly than the mouse and guinea pig. In contrast, the dog absorbed a lipid-soluble drug like procainamide at the same rate as the other four species. The results suggest that pulmonary absorption rates measured in small laboratory animals can be used to predict absorption rates in large animals.