Cardiohemodynamic and Electrophysiological Effects of Anti-influenza Drug Oseltamivir In Vivo and In Vitro

Electropharmacological effects of oseltamivir were studied in comparison with pilsicainide using halothane-anesthetized dogs (n = 4) and isolated left atrium of guinea pigs (n = 5). Oseltamivir (0.3, 3 and 30 mg/kg, i.v.) or pilsicainide (1 and 3 mg/kg, i.v.) was additionally administered to the dogs. The low dose of oseltamivir provided clinically relevant plasma concentrations with C _max of 4 μM. The low and middle doses of oseltamivir increased cardiac output, whereas the middle dose increased blood pressure and delayed intra-atrial conduction and ventricular repolarization. The high dose of oseltamivir exerted negative chronotropic, inotropic and hypotensive effects, while it delayed intra-atrial, atrioventricular nodal and intra-ventricular conduction and ventricular repolarization. Use-dependent delay of ventricular repolarization was observed after oseltamivir, whereas reverse use-dependent prolongation was induced by pilsicainide. Moreover, oseltamivir more selectively suppressed intra-atrial conduction than intra-ventricular conduction, which was less selective for pilsicainide. Action potential assay using isolated atrium indicated that oseltamivir (10 μM) decreased V _max more than pilsicainide (10 μM) and that oseltamivir (10–100 μM) prolonged action potential duration, which was not induced by pilsicainide (1–10 μM). Thus, oseltamivir in clinically relevant to its 10 times higher doses is relatively safe, whereas 10–100 times higher doses possess unique electrophysiological profile.