Tiazac (diltiazem hydrochloride)
The following drug information is obtained from various newswires, published
medical journal articles, and medical conference presentations.
Tiazac has been approved as a treatment for hypertension. The
once-daily calcium channel blocker reduces blood pressure of
hypertensive subjects. 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
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.
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.
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 was well tolerated in clinical trials. The most commonly
reported side effects were headache, peripheral edema, pain,
dizziness, and asthenia.
Mechanism of Action
Tiazac produces its antihypertensive effect primarily by
relaxation of vascular smooth muscle and the resultant decrease in
peripheral vascular resistance. The magnitude of blood pressure
reduction is related to the degree of hypertension: thus
hypertensive individuals experience an antihypertensive effect,
whereas there is only a modest fall in blood pressure in
Blood pressure normally varies throughout the day and night and
is influenced by the subject’s own circadian rhythm and external
stimuli. In hypertensive subjects, blood pressure needs 24-hour
control to achieve blood pressure levels that approach treatment