Diltiazem Hydrochloride

INDICATIONS AND USAGE Diltiazem hydrochloride tablets are indicated for the management of chronic stable angina and angina due to coronary artery spasm.

DOSAGE AND ADMINISTRATION Exertional Angina Pectoris Due to Atherosclerotic Coronary Artery Disease or Angina Pectoris at Rest Due to Coronary Artery Spasm: Dosage must be adjusted to each patient's needs. Starting with 30 mg four times daily, before meals and at bedtime, dosage should be increased gradually (given in divided doses three or four times daily) at 1- to 2-day intervals until optimum response is obtained. Although individual patients may respond to any dosage level, the average optimum dosage range appears to be 180 mg/day to 360 mg/day. There are no available data concerning dosage requirements in patients with impaired renal or hepatic function. If the drug must be used in such patients, titration should be carried out with particular caution. Concomitant Use with Other Cardiovascular Agents Sublingual NTG may be taken as required to abort acute anginal attacks during diltiazem hydrochloride therapy. Prophylactic Nitrate Therapy. diltiazem hydrochloride may be safely coadministered with short- and long- acting nitrates, but there have been no controlled studies to evaluate the antianginal effectiveness of this combination. Beta-blockers. (See WARNINGS and PRECAUTIONS .) 30 mg – Diltiazem hydrochloride tablets, USP may be swallowed whole, crushed, or chewed. Do not split diltiazem hydrochloride tablets. 60 mg, 90 mg, and 120 mg – Diltiazem hydrochloride tablets, USP may be swallowed whole, crushed, or chewed.

CONTRAINDICATIONS Diltiazem hydrochloride tablets are contraindicated in: • Patients with sick sinus syndrome except in the presence of a functioning ventricular pacemaker • Patients with second- or third-degree AV block except in the presence of a functioning ventricular pacemaker • Patients with hypotension (less than 90 mm Hg systolic) • Patients who have demonstrated hypersensitivity to the drug • Patients with acute myocardial infarction and pulmonary congestion documented by x-ray on admission

ADVERSE REACTIONS Serious adverse reactions have been rare in studies carried out to date, but it should be recognized that patients with impaired ventricular function and cardiac conduction abnormalities usually have been excluded. In domestic placebo-controlled angina trials, the incidence of adverse reactions reported during diltiazem hydrochloride therapy was not greater than that reported during placebo therapy. The following represent occurrences observed in clinical studies of angina patients. In many cases, the relationship to diltiazem hydrochloride has not been established. The most common occurrences from these studies, as well as their frequency of presentation, are edema (2.4%), headache (2.1%), nausea (1.9%), dizziness (1.5%), rash (1.3%), and asthenia (1.2%). In addition, the following events were reported infrequently (less than 1%): Cardiovascular: Angina, arrhythmia, AV block (first-degree), AV block (second- or third-degree – see WARNINGS, Cardiac Conduction ), bradycardia, bundle branch block, congestive heart failure, ECG abnormality, flushing, hypotension, palpitations, syncope, tachycardia, ventricular extrasystoles Nervous System: Abnormal dreams, amnesia, depression, gait abnormality, hallucinations, insomnia, nervousness, paresthesia, personality change, somnolence, tremor Gastrointestinal: Anorexia, constipation, diarrhea, dysgeusia, dyspepsia, mild elevations of alkaline phosphatase, SGOT, SGPT, and LDH (see WARNINGS, Acute Hepatic Injury ), thirst, vomiting, weight increase. Dermatological: Petechiae, photosensitivity, pruritus, urticaria Other: Amblyopia, CPK elevation, dry mouth, dyspnea, epistaxis, eye irritation, hyperglycemia, hyperuricemia, impotence, muscle cramps, nasal congestion, nocturia, osteoarticular pain, polyuria, sexual difficulties, tinnitus The following postmarketing events have been reported infrequently in patients receiving diltiazem hydrochloride tablets: acute generalized exanthematous pustulosis, allergic reactions, alopecia, angioedema (including facial or periorbital edema), asystole, erythema multiforme (including Stevens- Johnson syndrome, toxic epidermal necrolysis), extrapyramidal symptoms, gingival hyperplasia, hemolytic anemia, increased bleeding time, leukopenia, photosensitivity (including lichenoid keratosis and hyperpigmentation at sun-exposed skin areas), purpura, retinopathy, myopathy, and thrombocytopenia. There have been observed cases of a generalized rash, some characterized as leukocytoclastic vasculitis. In addition, events such as myocardial infarction have been observed, which are not readily distinguishable from the natural history of the disease in these patients. A definitive cause and effect relationship between these events and diltiazem hydrochloride therapy cannot yet be established. Exfoliative dermatitis (proven by rechallenge) has also been reported. To report SUSPECTED ADVERSE REACTIONS, contact ScieGen Pharmaceuticals, Inc. at 1-855-724-3436 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Drug Interactions Due to the potential for additive effects, caution and careful titration are warranted in patients receiving diltiazem hydrochloride concomitantly with any agents known to affect cardiac contractility and/or conduction (see WARNINGS ). Pharmacologic studies indicate that there may be additive effects in prolonging AV conduction when using beta-blockers or digitalis concomitantly with diltiazem hydrochloride (see WARNINGS ). As with all drugs, care should be exercised when treating patients with multiple medications. Diltiazem is both a substrate and an inhibitor of the cytochrome P450 3A4 enzyme system. Other drugs that are specific substrates, inhibitors, or inducers of this enzyme system may have a significant impact on the efficacy and side effect profile of diltiazem. Patients taking other drugs that are substrates of CYP450 3A4, especially patients with renal and/or hepatic impairment, may require dosage adjustment when starting or stopping concomitantly administered diltiazem in order to maintain optimum therapeutic blood levels. Anesthetics: The depression of cardiac contractility, conductivity, and automaticity, as well as the vascular dilation associated with anesthetics, may be potentiated by calcium channel blockers. When used concomitantly, anesthetics and calcium blockers should be titrated carefully. Benzodiazepines: Studies showed that diltiazem increased the AUC of midazolam and triazolam by 3- to 4-fold and the C max by 2-fold, compared to placebo. The elimination half-life of midazolam and triazolam also increased (1.5- to 2.5-fold) during coadministration with diltiazem. These pharmacokinetic effects seen during diltiazem coadministration can result in increased clinical effects (e.g., prolonged sedation) of both midazolam and triazolam. Beta-blockers. Controlled and uncontrolled domestic studies suggest that concomitant use of diltiazem hydrochloride and beta-blockers is usually well tolerated. Available data are not sufficient, however, to predict the effects of concomitant treatment, particularly in patients with left ventricular dysfunction or cardiac conduction abnormalities. Administration of diltiazem hydrochloride concomitantly with propranolol in five normal volunteers resulted in increased propranolol levels in all subjects, and bioavailability of propranolol was increased approximately 50%. In vitro , propranolol appears to be displaced from its binding sites by diltiazem. If combination therapy is initiated or withdrawn in conjunction with propranolol, an adjustment in the propranolol dose may be warranted (see WARNINGS ). Buspirone: In nine healthy subjects, diltiazem significantly increased the mean buspirone AUC 5.5-fold and C max 4.1-fold compared to placebo. The T 1/2 and T max of buspirone were not significantly affected by diltiazem. Enhanced effects and increased toxicity of buspirone may be possible during concomitant administration with diltiazem. Subsequent dose adjustments may be necessary during coadministration, and should be based on clinical assessment. Carbamazepine: Concomitant administration of diltiazem with carbamazepine has been reported to result in elevated serum levels of carbamazepine (40% to 72% increase) resulting in toxicity in some cases. Patients receiving these drugs concurrently should be monitored for a potential drug interaction. Cimetidine: A study in six healthy volunteers has shown a significant increase in peak diltiazem plasma levels (58%) and area-under-the-curve (53%) after a 1-week course of cimetidine at 1200 mg per day and a single dose of diltiazem 60 mg. Ranitidine produced smaller, nonsignificant increases. The effect may be mediated by cimetidine's known inhibition of hepatic cytochrome P450, the enzyme system responsible for the first-pass metabolism of diltiazem. Patients currently receiving diltiazem therapy should be carefully monitored for a change in pharmacological effect when initiating and discontinuing therapy with cimet …

Mechanisms of Action Although precise mechanisms of its antianginal actions are still being delineated, diltiazem hydrochloride is believed to act in the following ways: Angina Due to Coronary Artery Spasm: Diltiazem hydrochloride 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 hydrochloride. Exertional 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 exercise workloads. 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 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 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, 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. There are as yet few data on the interaction of diltiazem and betablockers. Resting heart rate is usually unchanged or slightly reduced by diltiazem. Intravenous diltiazem in doses of 20 mg prolongs AH conduction time and AV node functional and effective refractory periods approximately 20%. In a study involving single oral doses of 300 mg of diltiazem hydrochloride in six normal volunteers, the average maximum PR prolongation was 14% with no instances of greater than first-degree AV block. 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). Chronic oral administration of diltiazem hydrochloride in doses of up to 240 mg/day has resulted in small increases in PR interval but has not usually produced abnormal prolongation. Pharmacokinetics and Metabolism Diltiazem is well absorbed from the gastrointestinal tract and is subject to an extensive first-pass effect, giving an absolute bioavailability (compared to intravenous dosing) of about 40%. Diltiazem hydrochloride undergoes extensive metabolism in which 2% to 4% of the unchanged drug appears in the urine. In vitro binding studies show diltiazem hydrochloride is 70% to 80% bound to plasma proteins. Competitive in vitro ligand binding studies have also shown diltiazem hydrochloride binding is not altered by therapeutic concentrations of digoxin, hydrochlorothiazide, phenylbutazone, propranolol, salicylic acid, or warfarin. The plasma elimination half-life following single or multiple drug administration is approximately 3.0 to 4.5 hours. Desacetyl diltiazem is also present in the plasma at levels of 10% to …

DESCRIPTION Diltiazem hydrochloride, USP is a calcium ion cellular influx inhibitor (slow channel blocker or calcium antagonist). Chemically, diltiazem hydrochloride is 1,5-Benzothiazepin-4(5 H )-one, 3-(acetyloxy)-5-[2-(dimethylamino)ethyl]-2, 3-dihydro-2-(4-methoxyphenyl)-, monohydrochloride,(+)- cis -. The chemical structure is: Diltiazem hydrochloride, USP is a white, odourless, crystalline powder or small crystals. It is soluble in water, methanol, and chloroform. It has a molecular weight of 450.98. Each diltiazem hydrochloride tablet, USP contains 30 mg, 60 mg, 90 mg, or 120 mg diltiazem hydrochloride, USP. Also contains: colloidal silicon dioxide, D&C Yellow #10 aluminum lake (30 mg and 90 mg), FD&C Blue #1 brilliant blue aluminum lake (30 mg and 90 mg), hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, polyethylene glycol, talc and titanium dioxide. For oral administration. FDA approved dissolution test specifications differ from USP. structure

OVERDOSAGE The oral LD 50s in mice and rats range from 415 mg/kg to 740 mg/kg and from 560 mg/kg to 810 mg/kg, respectively. The intravenous LD 50s in these species were 60 mg/kg and 38 mg/kg, respectively. The oral LD 50s in dogs is considered to be in excess of 50 mg/kg, while lethality was seen in monkeys at 360 mg/kg. The toxic dose in man is not known. Due to extensive metabolism, blood levels after a standard dose of diltiazem can vary over tenfold, limiting the usefulness of blood levels in overdose cases. There have been reports of diltiazem overdose in amounts ranging from < 1 g to 18 g. Of cases with known outcome, most patients recovered and in cases with a fatal outcome, the majority involved multiple drug ingestion. Events observed following diltiazem overdose included bradycardia, hypotension, heart block, and cardiac failure. Most reports of overdose described some supportive medical measure and/or drug treatment. Bradycardia frequently responded favorably to atropine, as did heart block, although cardiac pacing was also frequently utilized to treat heart block. Fluids and vasopressors were used to maintain blood pressure, and in cases of cardiac failure, inotropic agents were administered. In addition, some patients received treatment with ventilatory support, gastric lavage, activated charcoal, and/or intravenous calcium. The effectiveness of intravenous calcium administration to reverse the pharmacological effects of diltiazem overdose has been inconsistent. In a few reported cases, overdose with calcium channel blockers associated with hypotension and bradycardia that was initially refractory to atropine became more responsive to atropine after the patients received intravenous calcium. In some cases intravenous calcium has been administered (1 g calcium chloride or 3 g calcium gluconate) over 5 minutes and repeated every 10 to 20 minutes as necessary. Calcium gluconate has also been administered as a continuous infusion at a rate of 2 g per hour for 10 hours. Infusions of calcium for 24 hours or more may be required. Patients should be monitored for signs of hypercalcemia. In the event of overdose or exaggerated response, appropriate supportive measures should be employed in addition to gastrointestinal decontamination. Diltiazem does not appear to be removed by peritoneal or hemodialysis. Limited data suggest that plasmapheresis or charcoal hemoperfusion may hasten diltiazem elimination following overdose. Based on the known pharmacological effects of diltiazem and/or reported clinical experiences, the following measures may be considered: Bradycardia: Administer atropine (0.60 mg to 1.0 mg). If there is no response to vagal blockade, administer isoproterenol cautiously. High-Degree AV Block: Treat as for bradycardia above. Fixed high-degree AV block should be treated with cardiac pacing. Cardiac Failure: Administer inotropic agents (isoproterenol, dopamine, or dobutamine) and diuretics. Hypotension: Vasopressors (e.g., dopamine or norepinephrine). Actual treatment and dosage should depend on the severity of the clinical situation and the judgment and experience of the treating physician.

HOW SUPPLIED Diltiazem hydrochloride tablets, USP, 30 mg are supplied in bottles of 100 with child-resistant closure (NDC 72578-199-01) and 500 (NDC 72578-199-05). Each green colored, round shaped, biconvex, film coated tablets debossed with "1867" on one side and plain on another side. Diltiazem hydrochloride tablets, USP, 60 mg are scored tablets supplied in bottles of 100 (NDC 72578-200-01) with child-resistant closure and 500 (NDC 72578-200-05). Each white to off white colored, round shaped, biconvex, film coated tablets debossed with "18" and "68" separated with scoreline on one side and plain on another side. Diltiazem hydrochloride tablets, USP, 90 mg are scored tablets supplied in bottles of 100 (NDC 72578-201-01) with child-resistant closure and 500 (NDC 72578-201-05). Each green colored, capsule shaped, biconvex, film coated tablets debossed with "18" and "69" separated with scoreline on one side and plain on another side. Diltiazem hydrochloride tablets, USP, 120 mg are scored tablets supplied in bottles of 100 (NDC 72578-202-01) with child-resistant closure and 500 (NDC 72578-202-05). Each white to off white colored, capsule shaped, biconvex, film coated tablets de bossed with "18" and "70" separated with scoreline on one side and plain on another side. Store at 25°C (77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature]. Avoid excessive humidity. Manufactured by: Zydus Lifesciences Ltd., Baddi-173205, India. Distributed by: Viona Pharmaceuticals Inc. Cranford, NJ 07016 Rev. 05/25