Abstract

Cassia angustifolia is a species of a plant from the Senna family that has traditionally been used as a laxative in different herbal products and commercial medicines. There are few described interactions between Senna and drugs, most of them related to electrolyte disturbances due to concomitant use with other laxatives or due to increased intestinal transit that may limit the absorption of drugs with low bioavailability. We present a case with supratherapeutic trough concentration of tacrolimus in a liver transplant patient after concomitant intake of tacrolimus and a herbal product based on Cassia angustifolia, suggesting a possible drug-plant interaction by means of P-glycoprotein. We observe an increase in their plasma concentration 2.8-fold and the AUC 2.1-fold.