Diltiazem hydrochloride is a calcium channel antagonist. It is a peripheral and coronary vasodilator with some negative inotropic activity. Diltiazem inhibits cardiac conduction particularly at the sino-atrial and atrioventricular nodes. Diltiazem has the following actions:

Antianginal: A direct dilatation of coronary arteries and arterioles proved oxygen supply to myocardial tissues. In addition dilatation of the peripheral vasculature reduces systemic pressure of cardiac "after load" which results in lessened stress and reduced oxygen requirements of the myocardial tissues.

Antiarrhythmic: The inhibited influx of calcium ions in cardiac tissues result in slowed electrophysiological activity through the S-A and A-V nodes without affecting accessory bypass conduction or altering normal atrial action potential or intraventricular conduction.

Antihypertensive: Reduces peripheral vascular resistance as a result of vasodilatation. More than 90% of an oral dose is rapidly absorbed. Protein binding is very high. Peak plasma concentration reaches within 30-60 minutes. It is metabolised in the liver and excreted (60%) through bile.

Diltiazem Hydrochloride sustained release tablet is indicated in the prophylaxis and treatment of angina pectoris. It is used in the management of classical and vasospastic angina pectoris. It has also been used in the treatment of essential hypertension. It is used for prophylaxis of some selected supraventricular tachyarrhythmias.

Mild to moderate hypertension: initially 90 mg or 120 mg twice daily (elderly once daily); up to 360 mg daily may be required (elderly upto 240 mg) daily.

Angina: initially 90 mg or 120 mg twice daily in divided doses may be required (elderly up to 240 mg daily).

Diltiazem Hydrochloride sustained release tablet is contraindicated in patients with known hypersensitivity to the drug, sick sinus syndrome, second or third degree AV block, severe hypertension or acute myocardial infarction and rediographically documented pulmonary congestion.

Bradycardia, sino-atrial block, atrioventricular block, hypertension, malaise, headache, hot flushes, GIT disturbances, oedema, hepatitis and depression reported.

Pregnancy & Lactation

There are no adequate and controlled studies to date with diltiazem in pregnant women, and the drug should be used during pregnancy only when the potential benefits justify the possible risk to the fetus. Because diltiazem is distributed into milk, women receiving the drug should not breastfeed their infants; an alternative method of infant feeding should be used if diltiazem therapy is considered necessary in nursing women.