Interspecies variation in ritodrine metabolism.

The metabolism of ritodrine has been studied in the rat, both in vitro and in vivo, and in the in vivo pregnant baboon, with the use of tritium-labeled drug as a probe. Combined enzymatic degradation and radiochromatography of the radioactive components of bile and urine show that ritodrine undergoes significant Phase l metabolism in addition to conjugation to both sulfate and glucuronide, as previously reported. The presence of more than one conjugate is shown, and evidence for major interspecies variation in patterns of metabolism and conjugation is presented, with comments on the applicability of results to human clinical use.