Transplantation. 2001 Jan; 71(2): 239-41.

Herbal supplements: a potential for drug interactions in transplant recipients.

Barone GW, Gurley BJ, Ketel BL, Abul-Ezz SR.

Department of Surgery, Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock 72205, USA.

BACKGROUND: Herbal dietary supplements represent a potential and possibly an overlooked cause for drug interactions in transplant recipients. METHODS: Two patients are reported which suggest that St. John's Wort (SJW) may induce cytochrome P-450 3A4 activity and/or P-glycoprotein expression. Both of these mechanisms are significantly involved in the metabolism and absorption of cyclosporine (CSA) and other immunosuppressants. RESULTS: After two renal transplant recipients started self-medicating with SJW, their CSA concentrations were consistently documented to be subtherapeutic. While on SJW, one patient developed acute graft rejection due to low CSA concentrations. In both patients, termination of SJW returned their CSA concentrations to therapeutic values. CONCLUSIONS: Patients taking SJW concomitantly with CSA or other medications whose absorption and metabolism are mediated by cytochrome P-450 and/or P-glycoprotein should require close monitoring. Potential herb-prescription drug interactions are not just limited to SJW. Inquiries regarding the usage of herbal supplements should be an integral component of a transplant recipient's medication history.