Investigating herb–drug interactions: The effect of Citrus aurantium fruit extract on the pharmacokinetics of amiodarone in rats

• For the first time data on the potential of interaction between C. aurantium extract and amiodarone is reported.
• The simultaneous oral co-administration of C. aurantium extract and amiodarone induced a delay in the tmax of the drug.
• A 14-day oral pre-treatment with C. aurantium extract induced a significant increase in the Cmax of amiodarone.
• The extent of systemic exposure to amiodarone was not affected by the co-administration or pre-treatment with C. aurantium.

Citrus aurantium extract has been largely used in weight loss and sports performance dietary supplements. However, the safety of C. aurantium-containing products has been questioned mainly due to the association of its use with adverse events in the cardiovascular system. Therefore, this work aimed to assess the potential for herb–drug interactions among a standardized C. aurantium extract (GMP certificate) and amiodarone (narrow therapeutic index drug) in rats. In a first pharmacokinetic study, rats were simultaneously co-administered with a single-dose of C. aurantium (164 mg/kg, p.o.) and amiodarone (50 mg/kg, p.o.); in a second study, rats were pre-treated during 14 days with C. aurantium (164 mg/kg/day, p.o.) and received amiodarone (50 mg/kg, p.o.) on the 15th day. Rats of the control groups received the corresponding volume of vehicle. Overall, after analysis of the pharmacokinetic data, it deserves to be highlighted the significant increase of the peak plasma concentration of amiodarone in rats pre-treated with C. aurantium extract, while the extent of systemic exposure was comparable between both groups. This paper reports, for the first time, data on the potential of herb–drug interaction between C. aurantium extract and amiodarone. However, specific clinical trials should be performed to confirm these results in humans.