Bepridil has inhibitory effects on both the slow calcium (L-type) and fast sodium inward currents in myocardial and vascular smooth muscle, interferes with calcium binding to calmodulin, and blocks both voltage and receptor operated calcium channels. Bepridil inhibits the transmembrane influx of calcium ions into cardiac and vascular smooth muscle. This has been demonstrated in isolated myocardial and vascular smooth muscle preparations in which both the slope of the calcium dose response curve and the maximum calcium-induced inotropic response were significantly reduced by bepridil. In cardiac myocytes in vitro, bepridil was shown to be tightly bound to actin. Bepridil regularly reduces heart rate and arterial pressure at rest and at a given level of exercise by dilating peripheral arterioles and reducing total peripheral resistance (afterload) against which the heart works.
Bepridil is a calcium channel blocker that has well characterized anti-anginal properties and known but poorly characterized type 1 anti-arrhythmic and anti-hypertensive properties. It is not related chemically to other calcium channel blockers such as diltiazem hydrochloride, nifedipine and verapamil hydrochloride.
There has been one experience with overdosage in which a patient inadvertently took a single dose of 1600 mg of bepridil. The patient was observed for 72 hours in intensive care, but no significant adverse experiences were noted.