The antiarrhythmic drug flecainide enhances aversion to HCl in mice.

Drug-induced taste disorders reduce quality of life, but little is known about the molecular mechanisms by which drugs induce taste disturbances. In this study, we investigated the short- and long-term effects of the antiarrhythmic drug flecainide, which is known to cause taste dysfunction. Analyses of behavioral responses (licking tests) revealed that mice given a single intraperitoneal injection of flecainide exhibited a significant reduction in preference for a sour tastant (HCl) but not for other taste solutions (NaCl, quinine, sucrose, KCl and monopotassium glutamate) when compared with controls. Mice administered a single dose of flecainide also had significantly higher taste nerve responses to HCl but not to other taste solutions. Compared with controls, mice administered flecainide once-daily for 30 days showed a reduced preference for HCl without any changes in the behavioral responses to other taste solutions. The electrophysiological experiments using HEK293T cells transiently expressing otopetrin-1 (Otop1, the mouse sour taste receptor) showed that flecainide rarely altered the responses to HCl. Taken together, our results suggest that flecainide specifically enhances the response to HCl in mice during short- and long- term administration. Although further studies will be needed to elucidate the molecular mechanisms, these findings provide new insights into the pathophysiology of drug-induced taste disorders. Significance Statement Drug-induced taste disorders reduce quality of life and can lead to nutritional disturbances. However, little is known about its molecular mechanisms. We focused on the antiarrhythmic drug flecainide inducing "unpleasant or bad taste" in human patients. Mice administered a single dose of flecainide exhibited a reduced preference for and higher taste nerve responses to HCl, sour tastants specifically. Flecainide had little change in response to HCl in HEK293T cells expressing the sour taste receptor, proton channel otopetrin-1 (Otop1). Our results suggest that flecainide enhances the responses of sour-sensing taste cells to HCl. Although further studies will be needed to elucidate the molecular mechanisms, these findings provide new insights into the pathophysiology of drug-induced taste disorders.