TAZTIA XT

TAZTIA XT- diltiazem hydrochloride capsule, extended release
Actavis Pharma, Inc.

DESCRIPTION

Rx Only

Diltiazem hydrochloride, USP is a calcium ion cellular influx inhibitor (slow channel blocker). Chemically, diltiazem hydrochloride is 1,5-Benzothiazepin-4(5H)-one, 3-(acetyloxy)-5-[2-(dimethylamino)ethyl]-2, 3-dihydro-2-(4-methoxyphenyl)-, monohydrochloride, (+)-cis -. The chemical structure is:

Chemical Structure
(click image for full-size original)

Diltiazem hydrochloride, USP is a white to off-white crystalline powder with a bitter taste. It is soluble in water, methanol and chloroform and has a molecular weight of 450.98. Diltiazem hydrochloride extend-release capsules, USP (once-a-day dosage) contain diltiazem hydrochloride in extended-release pellets at doses of 120, 180, 240, 300 and 360 mg.

Diltiazem hydrochloride extend-release capsules, USP (once-a-day dosage) also contains: black iron oxide, corn starch, ethylcellulose, D&C Yellow #10 Aluminum Lake, FD&C Blue #1 Aluminum Lake, FD&C Blue #2 Aluminum Lake, FD&C Red #40 Aluminum Lake, gelatin, hypromellose 2910, magnesium stearate, nonoxynol 100, pharmaceutical glaze, polysorbate 80, polyacrylic dispersion, povidone, propylene glycol, sucrose, talc and titanium dioxide. The 120 mg capsules also contain: D&C Red #28, FD&C Blue #1 and FD&C Red #40. The 180 mg capsules also contain: D&C Yellow #10, FD&C Blue #1 and FD&C Yellow #6. The 240 mg capsules also contain: D&C Red #28, FD&C Blue #1 and FD&C Red #40. The 300 mg capsules also contain: D&C Red #28, D&C Yellow #10, FD&C Blue #1, FD&C Red #40 and FD&C Yellow #6. The 360 mg capsules also contain: FD&C Blue #1.

For oral administration.

Meets USP requirements for dissolution test 15.

CLINICAL PHARMACOLOGY

The therapeutic effects of diltiazem hydrochloride are believed to be related to its ability to inhibit the cellular influx of calcium ions during membrane depolarization of cardiac and vascular smooth muscle.

Mechanisms of Action

Hypertension: Diltiazem 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 normotensives.

Angina: Diltiazem hydrochloride has been shown to produce increases in exercise tolerance, probably due to its ability to reduce myocardial oxygen demand. This is accomplished via reductions in heart rate and systemic blood pressure at submaximal and maximal workloads.

Diltiazem has been shown to be a potent dilator of coronary arteries, both epicardial and subendocardial. Spontaneous and ergonovine-induced coronary artery spasms are inhibited by diltiazem.

In animal models, diltiazem interferes with the slow inward (depolarizing) current in excitable tissue. It causes excitation-contraction uncoupling in various myocardial tissues without changes in the configuration of the action potential. Diltiazem produces relaxation of the coronary vascular smooth muscle and dilation of both large and small coronary vascular smooth muscle and dilation of both large and small coronary arteries at drug levels which cause little or no negative inotropic effect. The resultant increases in coronary blood flow (epicardial and subendocardial) occur in ischemic and nonischemic models and are accompanied by dose-dependent decreases in systemic blood pressure and decreases in peripheral resistance.

Hemodynamic and Electrophysiologic Effects

Like other calcium channel antagonists, diltiazem decreases sinoatrial and atrioventricular conduction in isolated tissues and has a negative inotropic effect in isolated preparations. In the intact animal, prolongation of the AH interval can be seen at higher doses.

In man, diltiazem prevents spontaneous and ergonovine-provoked coronary artery spasm. It causes a decrease in peripheral vascular resistance and a modest fall in blood pressure in normotensive individuals and, in exercise tolerance studies in patients with ischemic heart disease, reduces the heart rate-blood pressure product for any given workload. Studies to date, primarily in patients with good ventricular function, have not revealed evidence of a negative inotropic effect; cardiac output, ejection fraction, and left ventricular end-diastolic pressure have not been affected. Such data have no predictive value with respect to effects in patients with poor ventricular function, and increased heart failure has been reported in patients with preexisting impairment of ventricular function. There are as yet few data on the interaction of diltiazem and beta-blockers in patients with poor ventricular function. Resting heart rate is usually slightly reduced by diltiazem.

Diltiazem hydrochloride extended-release capsules (once-a-day dosage) produces antihypertensive effects both in the supine and standing positions. Postural hypotension is infrequently noted upon suddenly assuming an upright position. No reflex tachycardia is associated with the chronic antihypertensive effects.

Diltiazem hydrochloride decreases vascular resistance, increases cardiac output (by increasing stroke volume), and produces a slight decrease or no change in heart rate. During dynamic exercise, increases in diastolic pressure are inhibited while maximum achievable systolic pressure is usually reduced. Chronic therapy with diltiazem hydrochloride produces no change or an increase in plasma catecholamines. No increased activity of the renin-angiotensin-aldosterone axis has been observed. Diltiazem hydrochloride reduces the renal and peripheral effects of angiotensin II. Hypertensive animal models respond to diltiazem with reductions in blood pressure and increased urinary output and natriuresis without a change in urinary sodium/potassium ratio. In man, transient natriuresis and kaliuresis have been reported, but only in high intravenous doses of 0.5 mg/kg of body weight.

Diltiazem-associated prolongation of the AH interval is not more pronounced in patients with first-degree heart block. In patients with sick sinus syndrome, diltiazem significantly prolongs sinus cycle length (up to 50% in some cases). Intravenous diltiazem in doses of 20 mg prolongs AH conduction time and AV node functional and effective refractory periods by approximately 20%.

In two short-term, double-blind, placebo-controlled studies in 256 hypertensive patients with doses up to 540 mg/day, diltiazem hydrochloride extended-release capsules (once-a-day dosage) showed a clinically unimportant but statistically significant, dose-related increase in PR interval (0.008 seconds). There were no instances of greater than first-degree AV block in any of the clinical trials (see WARNINGS).

Pharmacodynamics

Hypertension: In short-term, double-blind, placebo-controlled clinical trials, diltiazem hydrochloride extended-release capsules (once-a-day dosage) demonstrated a dose-related antihypertensive response among patients with mild to moderate hypertension. In one parallel-group study of 198 patients diltiazem hydrochloride extended-release capsules (once-a-day dosage) were given for four weeks. The changes in diastolic blood pressure measured at trough (24 hours after the dose) for placebo, 90 mg, 180 mg, 360 mg and 540 mg were -5.4, -6.3, -6.2, -8.2, and -11.8 mm Hg, respectively. Supine diastolic blood pressure as well as standing diastolic and systolic blood pressures also showed statistically significant linear dose response effects.

In another clinical trial that followed a dose-escalation design, diltiazem hydrochloride extended-release capsules (once-a-day dosage) also reduced blood pressure in a linear dose-related manner. Supine diastolic blood pressure measured following two-week intervals of treatment was reduced by -3.7 mm Hg with 120 mg/day versus -2.0 mm Hg with placebo, by -7.6 mm Hg after escalation to 240 mg/day versus -2.3 mm Hg with placebo, by -8.1 mm Hg after escalation to 360 mg/day versus -0.9 mm Hg with placebo, and by -10.8 mm Hg after escalation to 480/540 mg/day versus -2.2 mm Hg with placebo.

Angina: In a double-blind parallel group placebo-controlled trial (approximately 50 patients/group, in patients with chronic stable angina), diltiazem hydrochloride at doses of 120 to 540 mg/day increased exercise tolerance time. At trough, 24 hours after dosing, exercise tolerance times using a Bruce exercise protocol, increased by 14, 26, 41, 33 and 32 seconds over baseline for placebo and the 120 mg, 240 mg, 360 mg, and 540 mg treated patient groups, respectively. At peak, 8 hours after dosing, exercise tolerance times relative to baseline were statistically significantly increased by 13, 38, 64, 55 and 42 seconds for placebo and 120 mg, 240 mg, 360 mg and 540 mg diltiazem hydrochloride treated patients, respectively. Compared to baseline, diltiazem hydrochloride treated patients experienced statistically significant reductions in anginal attacks and decreased nitroglycerin requirements when compared to placebo treated patients.

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