DILTIAZEM HYDROCHLORIDE

Diltiazem hydrochloride is a calcium ion 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-. Its molecular formula is C 22 H 26 N 2 O 4 S•HCl and its molecular weight is 450.98. Its structural formula is as follows: Diltiazem hydrochloride is a white to off-white crystalline powder with a bitter taste. It is soluble in water, methanol, and chloroform. FDA approved dissolution specification differ from the USP dissolution specification. Diltiazem Hydrochloride Extended-release Capsules, USP contain multiple units of diltiazem HCl extended-release 60 mg, resulting in 120 mg, 180 mg, or 240 mg dosage strengths allowing for the controlled release of diltiazem HCl over a 24-hour period. Inactive Ingredients: Diltiazem Hydrochloride Extended-release Capsules, USP also contain colloidal anhydrous silica, hydroxypropyl methyl cellulose, mannitol and magnesium stearate. The 120 mg capsule shell contains gelatin, titanium dioxide, sodium lauryl sulfate, FD &C Yellow 6, D &C Yellow 10. The 180 mg capsule shell contains gelatin, titanium dioxide, sodium lauryl sulfate, D &C Yellow 10, D &C Red 28, FD &C Red 40. The 240 mg capsule shell contains gelatin, titanium dioxide, sodium lauryl sulfate, iron oxide black, iron oxide red, iron oxide yellow. The imprinting ink of the tablet consists of shellac, iron oxide black and potassium hydroxide. For oral administration. Diltiazem hydrochloride Chemical Structure

Diltiazem Hydrochloride Extended-release Capsules, USP are indicated for the treatment of hypertension. Diltiazem hydrochloride may be used alone or in combination with other antihypertensive medications, such as diuretics. Diltiazem Hydrochloride Extended-release Capsules, USP are indicated for the management of chronic stable angina.

Hypertensive or anginal patients who are treated with other formulations of diltiazem can safely be switched to diltiazem hydrochloride extended-release capsules at the nearest equivalent total daily dose. Subsequent titration to higher or lower doses may, however, be necessary and should be initiated as clinically indicated. Studies have shown a slight increase in the rate of absorption of diltiazem hydrochloride extended-release capsules when ingested with a high-fat breakfast; therefore, administration in the morning on an empty stomach is recommended. Patients should be cautioned that the diltiazem hydrochloride extended-release capsules should not be opened, chewed or crushed, and should be swallowed whole. Dosage: Hypertension: Dosages must be adjusted to each patient’s needs, starting with 180 mg or 240 mg once daily. Based on the antihypertensive effect, the dose may be adjusted as needed. Individual patients, particularly ≥60 years of age, may respond to a lower dose of 120 mg. The usual dosage range studied in clinical trials was 180 mg to 480 mg once daily. Current clinical experience with the 540 mg dose is limited; the dose may be increased to 540 mg with little or no increased risk of adverse reactions. Doses should not exceed 540 mg once daily. While a dose of diltiazem hydrochloride extended-release capsules given once daily may produce an antihypertensive effect similar to the same total daily dose given in divided doses, individual dose adjustment may be needed. Dosage: Angina: Dosages for the treatment of angina should be adjusted to each patient’s needs, starting with a dose of 120 mg once daily, which may be titrated to doses of up to 480 mg once daily. When necessary, titration may be carried out over a 7 to 14 day period. Concomitant Use with Other Cardiovascular Agents. Sublingual Nitroglycerin may be taken as required to abort acute anginal attacks during diltiazem hydrochloride therapy. Prophylactic Nitrate Therapy – Diltiazem hydrochloride may be safely co-administered with short- and long-acting nitrates. Beta-blockers. (See WARNINGS and PRECAUTIONS .) Antihypertensives – Diltiazem hydrochloride has an additive antihypertensive effect when used with other antihypertensive agents. Therefore, the dosage of diltiazem hydrochloride or the concomitant antihypertensives may need to be adjusted when adding one to the other.

Diltiazem hydrochloride is contraindicated in: (1) patients with sick sinus syndrome except in the presence of a functioning ventricular pacemaker; (2) patients with second or third degree AV block except in the presence of a functioning ventricular pacemaker; (3) patients with hypotension (less than 90 mmHg systolic); (4) patients who have demonstrated hypersensitivity to the drug; and (5) patients with acute myocardial infarction and pulmonary congestion as documented by X-ray on admission.

Serious adverse reactions to diltiazem hydrochloride have been rare in studies with other formulations, as well as with diltiazem hydrochloride extended-release capsules. It should be recognized, however, that patients with impaired ventricular function and cardiac conduction abnormalities have usually been excluded from these studies. Hypertension: The most common adverse events (frequency ≥1%) in placebo-controlled, clinical hypertension studies with diltiazem hydrochloride extended-release. using daily doses up to 540 mg, are listed in the table below with placebo-treated patients included for comparison. MOST COMMON ADVERSE EVENTS IN DOUBLE-BLIND, PLACEBO-CONTROLLED HYPERTENSION TRIALS Diltiazem Hydrochloride Extended-Release Adverse events occurring in 1% or more of patients receiving diltiazem hydrochloride extended-release. Placebo Adverse Events n=303 n=87 (COSTART Term) # pts (%) # pts (%) rhinitis 29 (9.6) 7 (8.0) headache 27 (8.9) 12 (13.8) pharyngitis 17 (5.6) 4 (4.6) constipation 11 (3.6) 2 (2.3) cough increase 9 (3.0) 2 (2.3) flu syndrome 7 (2.3) 1 (1.1) edema, peripheral 7 (2.3) 0 (0.0) myalgia 7 (2.3) 0 (0.0) diarrhea 6 (2.0) 0 (0.0) vomiting 6 (2.0) 0 (0.0) sinusitis 6 (2.0) 1 (1.1) asthenia 5 (1.7) 0 (0.0) pain, back 5 (1.7) 2 (2.3) nausea 5 (1.7) 1 (1.1) dyspepsia 4 (1.3) 0 (0.0) vasodilatation 4 (1.3) 0 (0.0) injury, accident 4 (1.3) 0 (0.0) pain, abdominal 3 (1.0) 0 (0.0) arthrosis 3 (1.0) 0 (0.0) insomnia 3 (1.0) 0 (0.0) dyspnea 3 (1.0) 0 (0.0) rash 3 (1.0) 1 (1.1) tinnitus 3 (1.0) 0 (0.0) Angina: The most common adverse events (frequency ≥1%) in a placebo-controlled, short-term (2 week) clinical angina study with diltiazem hydrochloride extended-release are listed in the table below with placebo-treated patients included for comparison. In this trial, following a placebo phase, patients were randomly assigned to once daily doses of either 120, 240, or 480 mg of diltiazem hydrochloride extended-release. MOST COMMON ADVERSE EVENTS IN A DOUBLE-BLIND, PLACEBO-CONTROLLED SHORT-TERM, ANGINA TRIALS Diltiazem Hydrochloride Extended-Release Adverse events occurring in 1% or more of patients receiving diltiazem hydrochloride extended-release. Placebo Adverse Events n=139 n=50 (COSTART Term) # pts (%) # pts (%) asthenia 5 (3.6) 2 (4.0) headache 4 (2.9) 3 (6.0) pain, back 4 (2.9) 1 (2.0) rhinitis 4 (2.9) 1 (2.0) constipation 3 (2.2) 1 (2.0) nausea 3 (2.2) 0 (0.0) edema, peripheral 3 (2.2) 1 (2.0) dizziness 3 (2.2) 0 (0.0) cough, increased 3 (2.2) 0 (0.0) bradycardia 2 (1.4) 0 (0.0) fibrillation, atrial 2 (1.4) 0 (0.0) arthralgia 2 (1.4) 0 (0.0) dream, abnormal 2 (1.4) 0 (0.0) dyspnea 2 (1.4) 0 (0.0) pharyngitis 2 (1.4) 1 (2.0) Infrequent Adverse Events: The following additional events (COSTART Terms), listed by body system, were reported infrequently (less than 1%) in all subjects, hypertensive (n=425) or angina (n=318) patients who received diltiazem hydrochloride extended-release, or with other formulations of diltiazem. Hypertension: Cardiovascular: First-degree AV block, arrhythmia, postural hypotension, tachycardia, pallor, palpitations, phlebitis, ECG abnormality, ST elevation. Nervous System: Vertigo, hypertonia, paresthesia, dizziness, somnolence. Digestive System: Dry mouth, anorexia, tooth disorder, eructation. Skin and Appendages: Sweating, urticaria, skin hypertrophy (nevus). Respiratory System: Epistaxis, bronchitis, respiratory disorder. Urogenital System: Cystitis, kidney calculus, impotence, dysmenorrhea, vaginitis, prostate disease. Metabolic and Nutritional Disorders: Gout, edema. Musculoskeletal System: Arthralgia, bursitis, bone pain. Hemic and Lymphatic System: Lymphadenopathy. Body as a Whole: Pain, unevaluable reaction, neck pain, neck rigidity, fever, chest pain, malaise. Special Senses: Amblyopia (blurred vision), ear pain. Angina: Cardiovascular: Palpitations, AV block, sinus bradycardia, bigeminal extrasystole, angina pectoris, hypertension, hypotension, myocardial infarct, myocardial ischemia, syncope, vasodilatation, ventricular extrasystole. Nervous System: Abnormal thinking, neuropathy, paresthesia. Digestive System: Diarrhea, dyspepsia, vomiting, colitis, flatulence, GI hemorrhage, stomach ulcers. Skin and Appendages: Contact dermatitis, pruritus, sweating. Respiratory System: Respiratory distress. Urogenital System: Kidney failure, pyelonephritis, urinary tract infection. Metabolic and Nutritional Disorders: Weight increase. Musculoskeletal System: Myalgia. Body as a Whole: Chest pain, accidental injury, infection. Special Senses: Eye hemorrhage, ophthalmitis, otitis media, taste perversion, tinnitus. There have been post-marketing reports of Stevens-Johnson syndrome and toxic epidermal necrolysis associated with the use of diltiazem hydrochloride.

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 hydrochloride undergoes biotransformation by cytochrome P-450 mixed function oxidase. Co-administration of diltiazem hydrochloride with other agents which follow the same route of biotransformation may result in the competitive inhibition of metabolism. Especially in patients with renal and/or hepatic impairment, dosages of similarly metabolized drugs, particularly those of low therapeutic ratio such as cyclosporine, may require adjustment when starting or stopping concomitantly administered diltiazem hydrochloride to maintain optimum therapeutic blood levels. Concomitant administration of diltiazem with carbamazepine has been reported to result in elevated plasma levels of carbamazepine, resulting in toxicity in some cases. Beta-Blockers: Controlled and uncontrolled domestic studies suggest that concomitant use of diltiazem hydrochloride and beta-blockers is usually well-tolerated, but available data are not sufficient to predict the effects of concomitant treatment 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 the bioavailability of propranolol was increased approximately 50%. If combination therapy is initiated or withdrawn in conjunction with propranolol, an adjustment in the propranolol dose may be warranted. (See WARNINGS .) 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 1,200 mg per day and diltiazem 60 mg per day. Ranitidine produced smaller, nonsignificant increases. The effect may be mediated by cimetidine’s known inhibition of hepatic cytochrome P-450, 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 cimetidine. An adjustment in the diltiazem dose may be warranted. Clonidine: Sinus bradycardia resulting in hospitalization and pacemaker insertion has been reported in association with the use of clonidine concurrently with diltiazem. Monitor heart rate in patients receiving concomitant diltiazem and clonidine. Digitalis: Administration of diltiazem hydrochloride with digoxin in 24 healthy male subjects increased plasma digoxin concentrations approximately 20%. Another investigator found no increase in digoxin levels in 12 patients with coronary artery disease. Since there have been conflicting results regarding the effects of digoxin levels, it is recommended that digoxin levels be monitored when initiating, adjusting, and discontinuing diltiazem hydrochloride therapy to avoid possible over- or under-digitalization. (See WARNINGS .) 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 channel blockers should be titrated carefully. Statins: Diltiazem is an inhibitor of CYP3A4 and has been shown to increase significantly the AUC of some statins. The risk of myopathy and rhabdomyolysis with statins metabolized by CYP3A4 may be increased with concomitant use of diltiazem. When possible, use a non-CYP3A4-metabolized statin with diltiazem; otherwise, dose adjustments for both diltiazem and the statin should be considered along with close monitoring for signs and symptoms of any statin related adverse events. In a healthy volunteer cross-over study (N=10), co-administration of a single 20 mg dose of simvastatin at the end of a 14 day regimen with 120 mg twice daily diltiazem SR resulted in a 5-fold higher mean simvastatin AUC compared with simvastatin alone. High average steady-state exposures of diltiazem would result in a greater increase in simvastatin exposure. A daily dose of 480 mg of diltiazem would be expected to result in an 8-fold higher mean simvastatin AUC compared with simvastatin alone. If co-administration of simvastatin with diltiazem is required, limit the daily doses of simvastatin to 10 mg and diltiazem to 240 mg. In a ten-subject randomized, open label, 4-way cross-over study, co-administration of diltiazem (120 mg twice daily diltiazem SR for 2 weeks) with a single 20 mg dose of lovastatin resulted in 3- to 4-fold higher mean lovastatin AUC and C max values compared with lovastatin alone. In the same study, there was no significant change in 20 mg single dose pravastatin AUC and C max during diltiazem co-administration.