Effects of Dietary Factors on Drug Transport and Metabolism: The Impact on Dosage Guidelines in Transplant Patients

This is the authors' abstract. We don't add key points for this paper.

The success of organ transplantation can be endangered by low, high, or strongly fluctuating blood levels of calcineurin inhibitors (CNIs). CNI metabolism and transport by cytochrome P450 3A4 (CYP3A4) and transport protein P-glycoprotein (P-gp) are modified by phytochemicals in foods and herbal medications, but the prevalence of clinically meaningful interactions is unknown. The principal interaction mechanisms and in vitro and in vivo evidence for herbal interactions with the major metabolic routes of CNIs are discussed. On the basis of these mechanisms, provisional dietary guidelines for transplant patients are provided. Foods and herbs already identified as interaction triggers, as well as those with a strong inhibitory or stimulatory influence on CYP3A4 or P-gp, should be avoided. Furthermore, the role of herbal products suspected of causing interactions (even when evidence of this is lacking) should also be considered in the context of unexpected outcomes in CNI-treated patients. Introduction or withdrawal of herbal products should be followed by pharmacokinetic assessment of immunosuppressive therapy. Clinical Pharmacology & Therapeutics (2009); 85, 4, 439–443 doi:10.1038/clpt.2008.303