Diltiazem hydrochloride, a non-dihydropyridine derivative, is a member of the group of drugs known as benzothiazepines, which are a class of calcium channel blockers used in the treatment of hypertension , angina and certain types of arrhythmia. It is a class III antianginal and a class IV antiarrhythmic [1]. Diltiazem hydrochloride exerts its pharmacological action by inhibiting the transmembrane influx of extracellular calcium ions across the membranes of myocardial cells and vascular smooth muscle cells, without altering serum calcium concentrations. It is a peripheral arterial vasodilator that acts directly on vascular smooth muscle, causing a reduction in peripheral vascular resistance and blood pressure. It has substantial inhibitory effects on the cardiac conduction system, acting primarily at the atrioventricular (AV) node to slow conduction time and prolong AV node refractoriness. Although it is the cornerstone of treatment and management of hypertension, angina and arrhythmia, it poses a major pharmacokinetic problem. Despite the fact that mad...