Japan Tobacco is developing the mixed action ion channel blocker, JTV-519, which has potential use as an antiarrhythmic [285800]. The drug is a novel cardioprotectant derivative of 1,4-benzothiazepine for which phase I trials were completed in the third quarter of 1998; phase II trials started in the fourth quarter of 1998 for the potential treatment of myocardial infarction [320195]. Studies have shown that JTV-519 has a strong cardioprotective effect against catecholamine-induced myocardial injury and against ischemia/reperfusion injury [316749]. In experimental myofibrillar overcontraction models, it demonstrated greater cardioprotectant effects than propranolol, verapamil and diltiazem [171668].