Clinical Results

In a major comparative trial of single-drug therapy for hypertension, diltiazem showed blood pressure control greater than or comparable to that of six other antihypertensives from different drug classes. African-American patients in the study responded especially well to diltiazem therapy, while Caucasians responded well to all drug classes.

Doses of Tiazac up to 360 mg exhibited a side-effect profile similar to that of the lower doses, and similar to placebo. Tiazac can be safely dosed up to 540 mg. In clinical trials, absorption of Tiazac was not affected by food intake: Tiazac can be taken with or without food, even high-fat meals.

Tiazac showed no clinically significant changes in ECG readings, no increases in 2nd or 3rd-degree AV heart block and no more than a slight decrease in heart rate.

Tiazac has been shown to significantly reduce both angina attack rates and nitroglycerin consumption. Tiazac's central effects and peripheral vasodilating action balanced oxygen supply and demand producing significantly greater increases in total duration of exercise compared to placebo. Additionally, Tiazac effectively reduced blood pressure of hypertensive patients over a 24-hour dosing interval.

Side Effects

Tiazac was well tolerated in clinical trials. The most commonly reported side effects were headache, peripheral edema, pain, dizziness, and asthenia.

Tiazac, as with all diltiazem formulations, should not be used in subjects with severe hypotension (less than 90 mm Hg systolic), acute myocardial infarction and pulmonary congestion documented by x-ray on admission, subjects with sick sinus syndrome or 2nd/3rd-degree AV block (unless used with a pacemaker), and subjects who have demonstrated hypersensitivity to the drug. This drug should be used with caution in subjects with impaired kidney, liver, or heart function.

Mechanism of Action

Through its extended-release, osmotic diffusion system of concentrated diltiazem beads, Tiazac delivers smooth 24-hour plasma levels, which are highly correlated with blood pressure measurements. When properly dosed, Tiazac provides smooth and predictable 24-hour blood pressure control. A greater blood pressure reduction is achieved with Tiazac when blood pressure is at its highest, yet Tiazac achieves blood pressure reduction without causing hypotension during periods of lower blood pressure.

Tiazac, a highly concentrated formulation of diltiazem, enables more drug to be contained inside a smaller capsule. This formulation allows for both smaller capsules for a given dosage, relative to the same dose of other once-daily diltiazem products, and for five dosage strengths: 120, 180, 240, 300, and 360 mg.