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Evidence-Based Complementary and Alternative Medicine
Volume 2012 (2012), Article ID 428560, 10 pages
Research Article

Herb-Drug Interaction of Paullinia cupana (Guarana) Seed Extract on the Pharmacokinetics of Amiodarone in Rats

1Laboratory of Pharmacology, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
2Centre for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-517 Coimbra, Portugal
3Health Sciences Research Centre (CICS), University of Beira Interior (UBI), 6200-506 Covilhã, Portugal
4Department of Internal Medicine, Amato Lusitano Hospital, 6000-085 Castelo Branco, Portugal

Received 14 September 2012; Accepted 10 November 2012

Academic Editor: Ken Yasukawa

Copyright © 2012 Márcio Rodrigues et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Paullinia cupana is used in weight-loss programs as a constituent of medicinal/dietary supplements. This study aimed to assess a potential herb-drug interaction among a standardized (certified) Paullinia cupana extract and amiodarone (narrow therapeutic index drug) in rats. In a first pharmacokinetic study rats were simultaneously coadministered with a single dose of Paullinia cupana (821 mg/kg, p.o.) and amiodarone (50 mg/kg, p.o.), and in a second study rats were pretreated during 14 days with Paullinia cupana (821 mg/kg/day, p.o.) receiving amiodarone (50 mg/kg, p.o.) on the 15th day. Rats of the control groups received the corresponding volume of vehicle. Blood samples were collected at several time points after amiodarone dosing, and several tissues were harvested at the end of the experiments (24 h after dose). Plasma and tissue concentrations of amiodarone and its major metabolite (mono-N-desethylamiodarone) were measured and analysed. A significant reduction in the peak plasma concentration (73.2%) and in the extent of systemic exposure (57.8%) to amiodarone was found in rats simultaneously treated with Paullinia cupana and amiodarone; a decrease in tissue concentrations was also observed. This paper reports for the first time an herb-drug interaction between Paullinia cupana extract and amiodarone, which determined a great decrease on amiodarone bioavailability in rats.