title: St John's wort: a hidden risk for transplant patients.
abstract: Herbal medications may cause prescription drug interactions in transplant recipients. After 2 of our kidney transplant recipients started self-medicating with St John's wort, their cyclosporine concentrations were consistently documented to be subtherapeutic. While on St John's wort, one patient developed acute rejection possibly due to low cyclosporine concentrations. Termination of St John's wort returned both patients' cyclosporine concentrations to therapeutic values. Based on the Naranjo Adverse Drug Reaction Probability Scale, our report would achieve a "probable" score, which supports the existence of a St John's wort-cyclosporine adverse drug interaction. St John's wort may induce cytochrome P-450 3A4 activity and/or P-glycoprotein expression, which are both involved in the metabolism and absorption of cyclosporine. Patients using St John's wort concomitantly with cyclosporine or other medications with similar absorption and/or metabolism to cyclosporine need close monitoring. Transplant coordinators are in a critical position to educate transplant recipients about the potential risks of herbal medication usage.
authors.affiliation: University of Arkansas for Medical Sciences, Little Rock, Ark., USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Turton-Weeks
authors.forename: G W
authors.initials: GW
authors.lastname: Barone
authors.forename: B J
authors.initials: BJ
authors.lastname: Gurley
authors.forename: B L
authors.initials: BL
authors.lastname: Ketel
authors.forename: M L
authors.initials: ML
authors.lastname: Lightfoot
authors.forename: S R
authors.initials: SR
authors.lastname: Abul-Ezz
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000328:Adult; D016572:Cyclosporine / Q000493:pharmacokinetics*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D019587:Dietary Supplements; D004347:Drug Interactions; D005260:Female; D006084:Graft Rejection / Q000276:immunology*; D006801:Humans; D020902:Hypericum / Q000009:adverse effects*; D007166:Immunosuppressive Agents / Q000493:pharmacokinetics*; D016030:Kidney Transplantation; D016035:Pancreas Transplantation; D028321:Plant Preparations / Q000009:adverse effects*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D007166:Immunosuppressive Agents; D028321:Plant Preparations; D016572:Cyclosporine; D003577:Cytochrome P-450 Enzyme System