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.

Film-coated formulation:

• Usual dose: The usual dose of Diltiazem Hydrochloride film coated tablet is 60 mg thrice daily. However patient's response may vary and dosage requirements can differ significantly between individual patients. If necessary, the divided dose may be increased to 180-300 mg/day. Dosage may be started as 30 mg four times daily and increasing at 1 to 2 days intervals until the optimum response is achieved. Higher doses upto 480 mg/day have been used with benefit in some patients especially in unstable angina.
• Elderly and patients with impaired hepatic or renal function: The recommended starting dose is 60 mg twice daily. The heart rate should be measured regularly and the dose should not be increased if the heart rate falls below 50 beats per minute.

Sustained release formulation:

• 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).

Concomitant prophylactic therapy with short-or long-acting nitrates may be administered safely during diltiazem therapy. Diltiazem recommended caution and careful dosage titration when diltiazem is administered concomitantly with other drugs that can affect cardiac contractility and/ or conduction.

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.

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.

Keep below 30°C temperature, away from light & moisture. Keep out of the reach of children.