A New York physician urged caution in extrapolating data on the teratogenic effects of drugs obtained in laboratory animals to humans at the 131st annual meeting of the American Association for the Advancement of Science in Montreal.
John J. Burns, MD, director of research at Burroughs Wellcome and Company, Tuckahoe, NY, discussed several ways in which differences in species, long-term administration in high doses, and other factors regarding metabolization and distribution of a drug may affect the evaluation of the drug's teratogenicity.
"Species differing in drug metabolism make it difficult to project pharmacological and toxicological data obtained in experimental animals to man," he said. He attributed this difficulty to differences in the actual rate of metabolism as well as to qualitative differences in metabolic pathways. Studies with an anti-inflammatory agent, phenylbutazone, show that a drug is metabolized in man at a very slow rate with a half-life which averages three