Death by lemonade?

The following report is about a prescription of drug poisoning caused by accident. A young, healthy woman was taken ill with gastroenteritis and treated with loperamide symptomatically. The social history was uneventful; in particular, there was no drug addiction involved. As the woman had imbibed a large quantity of beverages containing quinine the days before, the loperamide she then took induced a central mu-receptor effect which, in turn, led to a reduction of vigilance followed by aspiration. It has long been known that there are many medicines (amiodarone, azithromycin, captopril, clarithromycin) which inhibit efflux transporters (ABC transporters, para-glycoprotein-type (P-gp)). Efflux transporters are able to transport substances against a concentration gradient, a process requiring the expenditure of energy. This effect can be used in cancer-therapy. Quinine and the stereoisomer quinidine are P-gp inhibitors and thus lead to a central accumulation of the mu-receptor-agonist loperamide. In the drug scene, this effect is used to gain a central effect. For this reason, quinine which was freely available in Germany until April 2015 is now only available on prescription, and has been removed from the US market completely.