['To examine the effect of the concurrent administration of increasing amounts of grapefruit juice, an inhibitor of drug metabolism, on the steady-state pharmacokinetics of cyclosporine.', 'Open-label, three-period crossover, food-drug interaction study in stable renal transplant patients.', 'A university-affiliated clinical research center.', 'Sixteen stable renal transplant recipients.', 'Cyclosporine was administered with 240 ml of water, 240 ml of grapefruit juice, or several 240-ml glasses of grapefruit juice, and serial blood samples were taken to estimate the effect of grapefruit juice on cyclosporine pharmacokinetics.', 'Grapefruit juice caused a significant increase in cyclosporine area under the curve, however, no significant effect was seen in other pharmacokinetic parameters. Grapefruit juice caused an increase in the 24-hour trough cyclosporine concentration, which may be of clinical significance if long-term ingestion of grapefruit juice is recommended.'] Does interaction between cyclosporine and grapefruit juice require long-term ingestion in stable renal transplant recipients?