Diltiazem HCL, Extended-Release Capsules

The following drug information is obtained from various newswires, published medical journal articles, and medical conference presentations.

Approval Status:

Approved January 2000

Specific Treatments:

Indicated for the treatment of hypertension; for use alone or in combination with other anti-hypertensive medications

General Information

The Diltiazem Hydrochloride extended-release capsules, taken in 120 to 240 mg a day doses, are principally used to reduce high blood pressure (hypertension).

According to the American Heart Association, high blood pressure in adults defined as a blood pressure greater than or equal to 140 mm Hg systolic pressure or greater than or equal to 90 mm Hg diastolic pressure. High blood pressure has been directly linked to increases in the risk of various heart and brain conditions such as coronary heart disease and stroke.

While high blood pressure can occur in anyone, high risk groups include blacks, middle-aged and elderly adults, obese people, heavy drinkers, and women taking oral contraceptives.

Clinical Results

Clinical studies compared the Diltiazem HCL extended release capsules with the Diltiazem HCL tablets. The two forms of the drug were shown to have similar trends in half-life, despite the difference in absorption rate. It was found that 95% of the extended-release capsule is absorbed throughout the dosing interval. The capsules take effect within two to three hours and active effects are detected for 10 to 14 hours.

Side Effects

Common side effects include headache, drowsiness, swelling of feet and ankles, constipation, nausea, sudden weight gain, and fatigue.

More serious, but less common side effects include, irregular or slow heartbeat, shortness of breath, and fatigue caused by heart failure.

There may be some drug interactions between Diltiazem HCL and aspirin, beta-blockers, digitalis preparations, carbamazepine, cyclosporine, digoxin, lithium, oral diabetes agents, phenytoin, rifampin, cimetidine, fluvoxamine, or ranitidine.


Suddenly discontinuing use of this drug may cause serious health problems. Any discontinuance of the drug should be in gradual dosage reductions.

Mechanism of Action

Diltiazem interferes with the movement of calcium into heart muscle cells and the smooth muscle cells in the walls of the arteries. This action relaxes blood vessels (causing them to widen), which lowers blood pressure, increases the blood supply to the heart, and decreases the hearts overall workload. "from www.DiscoveryHealth.com"

Literature References

For a brief overview of the drug Diltiazem HCL, visit Yahoo! Health

Visit the American Heart Association web site to find out more about the risks involved with high blood pressure.

Additional Information

Diltiazem Hydrochloride is also available in tablet form to relieve and control angina (chest pain associated with heart disease) and in injection form to correct cardiac arrhythmia (heartbeat irregularities).