Erythromycin breath test and clinical transplantation

The intravenous 14C-erythromycin breath test (ERMBT) appears to be a convenient and reproducible means of measuring the activity of a major drug-metabolizing enzyme present in the liver, termed CYP3A4. Interpatient differences in liver CYP3A4 activity, as measured by the ERMBT, seem to account, for the most part, for interindividual differences in the kinetics of cyclosporin A and FK506. The predictability of the test may be improved as an oral form of the test and improved oral formulations of transplant medications are developed. Although the ERMBT is a promising research tool, its role in clinical transplantation has yet to be defined.