DILTIAZEM: 14,726 Adverse Event Reports & Safety Profile

DESCRIPTION Diltiazem hydrochloride 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 freely soluble in chloroform, in formic acid, in methanol, and in water; sparingly soluble in dehydrated alcohol; insoluble in ether. It has a molecular weight of 450.98. Diltiazem hydrochloride extended-release capsule, USP is formulated as a once-a-day extended-release capsule containing 120 mg diltiazem hydrochloride, USP (equivalent to 110.3 mg diltiazem), 180 mg diltiazem hydrochloride, USP (equivalent to 165.45 mg diltiazem), 240 mg diltiazem hydrochloride, USP (equivalent to 220.6 mg diltiazem), 300 mg diltiazem hydrochloride, USP (equivalent to 275.75 mg diltiazem), or 360 mg diltiazem hydrochloride, USP (equivalent to 330.9 mg diltiazem). Each capsule contains the following inactive ingredients: acetyl tributyl citrate, ammonio methacrylate copolymer type A, ammonio methacrylate copolymer type B, colloidal silicon dioxide, gelatin, hypromellose, sodium lauryl sulfate, sugar sphere, talc and titanium dioxide. Additionally each 120 mg capsule shell contains D & C yellow # 10, FD & C blue # 1 and FD & C red # 40; each 180 mg capsule shell contains FD & C blue # 1, FD & C red # 3 and iron oxide black; each 240 mg capsule shell contains FD & C blue # 1 and FD & C red # 3; each 300 mg capsule shell contains D & C yellow # 10, FD & C blue # 1, FD & C red # 40 and iron oxide black; each 360 mg capsule shell contains iron oxide black. Each capsule is printed with black pharmaceutical ink which contains black iron oxide, butyl alcohol, dehydrated alcohol, isopropyl alcohol, potassium hydroxide, propylene glycol, shellac and strong ammonia solution.

Diltiazem Hydrochloride

Extended-release Capsule, USP meets USP Dissolution Test 3. For oral administration. figure

AND USAGE Matzim LA (diltiazem hydrochloride) extended-release tablets are a nondihydropyridine calcium channel blocker indicated for: treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. It can be used alone or in combination with other antihypertensives. ( 1.1 ) improving exercise tolerance in patients with chronic stable angina. ( 1.2 )

1.1 Hypertension Matzim LA (diltiazem hydrochloride) extended-release tablets are indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes including this drug. Control of high blood pressure should be part of comprehensive cardiovascular risk management, including, as appropriate, lipid control, diabetes management, antithrombotic therapy, smoking cessation, exercise, and limited sodium intake. Many patients will require more than one drug to achieve blood pressure goals. For specific advice on goals and management, see published guidelines, such as those of the National High Blood Pressure Education Program’s Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC). Numerous antihypertensive drugs, from a variety of pharmacologic classes and with different mechanisms of action, have been shown in randomized controlled trials to reduce cardiovascular morbidity and mortality, and it can be concluded that it is blood pressure reduction, and not some other pharmacologic property of the drugs, that is largely responsible for those benefits. The largest and most consistent cardiovascular outcome benefit has been a reduction in the risk of stroke, but reductions in myocardial infarction and cardiovascular mortality also have been seen regularly. Elevated systolic or diastolic pressure causes increased cardiovascular risk, and the absolute risk increase per mm Hg is greater at higher blood pressures, so that even modest reductions of severe hypertension can provide substantial benefit. Relative risk reduction from blood pressure reduction is similar across populations with varying absolute risk, so the absolute benefit is greater in patients who are at higher risk independent of their hypertension (for example, patients with diabetes or hyperlipidemia), and such patients would be expected to benefit from more aggressive treatment to a lower blood pressure goal. Some antihypertensive drugs have smaller blood pressure effects (as monotherapy) in black patients, and many antihypertensive drugs have additional approved indications and effects (e.g., on angina, heart failure, or diabetic kidney disease). These considerations may guide selection of therapy. Matzim LA (diltiazem hydrochloride) extended-release tablets may be used alone or in combination with other antihypertensive medications.

1.2 Angina Matzim LA (diltiazem hydrochloride) extended-release tablets are indicated to improve exercise tolerance in patients with chronic stable angina.

DOSAGE AND ADMINISTRATION Direct Intravenous Single Injections (Bolus) The initial dose of diltiazem hydrochloride injection should be 0.25 mg/kg actual body weight as a bolus administered over 2 minutes (20 mg is a reasonable dose for the average patient). If response is inadequate, a second dose may be administered after 15 minutes. The second bolus dose of diltiazem hydrochloride injection should be 0.35 mg/kg actual body weight administered over 2 minutes (25 mg is a reasonable dose for the average patient). Subsequent intravenous bolus doses should be individualized for each patient. Patients with low body weights should be dosed on a mg/kg basis. Some patients may respond to an initial dose of 0.15 mg/kg, although duration of action may be shorter. Experience with this dose is limited.

Continuous Intravenous Infusion

For continued reduction of the heart rate (up to 24 hours) in patients with atrial fibrillation or atrial flutter, an intravenous infusion of diltiazem hydrochloride injection may be administered. Immediately following bolus administration of 20 mg (0.25 mg/kg) or 25 mg (0.35 mg/kg) diltiazem hydrochloride injection and reduction of heart rate, begin an intravenous infusion of diltiazem hydrochloride injection. The recommended initial infusion rate of diltiazem hydrochloride injection is 10 mg/h. Some patients may maintain response to an initial rate of 5 mg/h. The infusion rate may be increased in 5 mg/h increments up to 15 mg/h as needed, if further reduction in heart rate is required. The infusion may be maintained for up to 24 hours. Diltiazem shows dose-dependent, non-linear pharmacokinetics. Duration of infusion longer than 24 hours and infusion rates greater than 15 mg/h have not been studied. Therefore, infusion duration exceeding 24 hours and infusion rates exceeding 15 mg/h are not recommended. Dilution: To prepare diltiazem hydrochloride injection for continuous intravenous infusion, aseptically transfer the appropriate quantity (see chart) of diltiazem hydrochloride injection to the desired volume of either Normal Saline, D5W, or D5W/0.45% NaCl. Mix thoroughly. Keep diluted diltiazem hydrochloride injection refrigerated until use. Use within 24 hours.

Diluent Volume

Quantity of Diltiazem hydrochloride injection Final Concentration Administration Dose* Infusion Rate 100mL 125 mg(25mL)

Final Volume

125 mL 1 mg/mL 10 mg/h 15 mg/h 10 mL/h 15 mL/h 250 mL 250 mg (50 mL)

Final Volume

300 mL 0.83 mg/mL 10 mg/h 15 mg/h 12 mL/h 18 mL/h 500mL 250 mg(50mL)

Final Volume

550 mL 0.45 mg/mL 10 mg/h 15 mg/h 22 mL/h 33 mL/h * 5 mg/h may be appropriate for some patients. Compatibility: Diltiazem hydrochloride injection was tested for compatibility with three commonly used intravenous fluids at a maximal concentration of 1 mg diltiazem hydrochloride per milliliter. Diltiazem hydrochloride injection was found to be physically compatible and chemically stable in the following parenteral solutions for at least 24 hours when stored in glass or polyvinylchloride (PVC) bags at controlled room temperature 15° to 30°C (59° to 86°F) or under refrigeration 2° to 8°C (36° to 46°F). dextrose (5%) injection, USP sodium chloride (0.9%) injection, USP dextrose (5%) and sodium chloride (0.45%) injection, USP Physical Incompatibilities: Because of potential physical incompatibilities, it is recommended that diltiazem hydrochloride injection not be mixed with any other drugs in the same container. If possible, it is recommended that diltiazem hydrochloride injection not be co-infused in the same intravenous line. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit. Physical incompatibilities (precipitate formation or cloudiness) were observed when diltiazem hydrochloride injection was infused in the same intravenous line with the following drugs: acetazolamide, acyclovir, aminophylline, ampicillin, ampicillin sodium/sulbactam sodium, cefamandole, cefoperazone, diazepam, furosemide, hydrocortisone sodium succinate, insulin (regular: 100 units/mL), methylprednisolone sodium succinate, mezlocillin, nafcillin, phenytoin, rifampin, and sodium bicarbonate. Transition to Further Antiarrhythmic Therapy Transition to other antiarrhythmic agents following administration of diltiazem hydrochloride injection is generally safe. However, reference should be made to the respective agent manufacturer's package insert for information relative to dosage and administration. In controlled clinical trials, therapy with antiarrhythmic agents to maintain reduced heart rate in atrial fibrillation or atrial flutter or for prophylaxis of PSVT was generally started within 3 hours after bolus administration of diltiazem hydrochloride injection. These antiarrhythmic agents were intravenous or oral digoxin, Class 1 antiarrhythmics (e.g., quinidine, procainamide), calcium channel blockers, and oral beta-blockers. Experience in the use of antiarrhythmic agents following maintenance infusion of diltiazem hydrochloride injection is limited. Patients should be dosed on an individual basis and reference should be made to the respective manufacturer's package insert for information relative to dosage and administration.

CONTRAINDICATIONS Injectable forms of diltiazem are 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 severe hypotension or cardiogenic shock. 4. Patients who have demonstrated hypersensitivity to the drug. 5. Intravenous diltiazem and intravenous beta-blockers should not be administered together or in close proximity (within a few hours). 6. Patients with atrial fibrillation or atrial flutter associated with an accessory bypass tract such as in WPW syndrome or short PR syndrome. As with other agents which slow AV nodal conduction and do not prolong the refractoriness of the accessory pathway (e.g., verapamil, digoxin), in rare instances patients in atrial fibrillation or atrial flutter associated with an accessory bypass tract may experience a potentially life-threatening increase in heart rate accompanied by hypotension when treated with diltiazem hydrochloride injection. As such, the initial use of diltiazem hydrochloride injection should be, if possible, in a setting where monitoring and resuscitation capabilities, including DC cardioversion/defibrillation, are present (see OVERDOSAGE). Once familiarity of the patient's response is established, use in an office setting may be acceptable. 7. Patients with ventricular tachycardia. Administration of other calcium channel blockers to patients with wide complex tachycardia (QRS ≥0.12 seconds) has resulted in hemodynamic deterioration and ventricular fibrillation. It is important that an accurate pretreatment diagnosis distinguish wide complex QRS tachycardia of supraventricular origin from that of ventricular origin prior to administration of diltiazem hydrochloride injection.

ADVERSE REACTIONS Serious adverse reactions to diltiazem hydrochloride have been rare in studies with other formulations, as well as with Diltiazem Hydrochloride Extended-Release Capsules, USP (Once-a-day dosage). 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 Capsules, USP (Once-a-day dosage) 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 Adverse Events (COSTART Term)

Diltiazem Hydrochloride

Extended-Release Capsules, USP (Once-a-day dosage)* N = 303 # pts (%) Placebo N = 87 # 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) *Adverse events occurring in 1% or more of patients receiving Diltiazem Hydrochloride Extended-Release Capsules, USP (Once-a-day dosage).

Angina

The most common adverse events (frequency ≥1%) in a placebo-controlled, short-term (2 week) clinical angina study with Diltiazem Hydrochloride Extended-Release Capsules, USP (Once-a-day dosage) 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 Capsules, USP (Once-a-day dosage). MOST COMMON ADVERSE EVENTS IN A DOUBLE-BLIND, PLACEBO-CONTROLLED SHORT-TERM, ANGINA TRIAL Adverse Events (COSTART Term)

Diltiazem Hydrochloride

Extended-Release Capsules, USP (Once-a-day dosage)* N = 139 # pts (%) Placebo N = 50 # 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) * Adverse events occurring in 1% or more of patients receiving Diltiazem Hydrochloride Extended-Release Capsules, USP (Once-a-day dosage).

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 Capsules, USP (Once-a-day dosage), 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.

WARNINGS 1.

Cardiac

Conduction - Diltiazem prolongs AV nodal conduction and refractoriness that may rarely result in second- or third-degree AV block in sinus rhythm. Concomitant use of diltiazem with agents known to affect cardiac conduction may result in additive effects (see Drug Interactions). If high-degree AV block occurs in sinus rhythm, intravenous diltiazem should be discontinued and appropriate supportive measures instituted (see OVERDOSAGE). 2.

Congestive Heart

Failure - Although diltiazem has a negative inotropic effect in isolated animal tissue preparations, hemodynamic studies in humans with normal ventricular function and in patients with a compromised myocardium, such as severe CHF, acute MI, and hypertrophic cardiomyopathy, have not shown a reduction in cardiac index nor consistent negative effects on contractility (dp/dt). Administration of oral diltiazem in patients with acute myocardial infarction and pulmonary congestion documented by x-ray on admission is contraindicated. Experience with the use of diltiazem hydrochloride injection in patients with impaired ventricular function is limited. Caution should be exercised when using the drug in such patients. 3. Hypotension - Decreases in blood pressure associated with diltiazem hydrochloride injection therapy may occasionally result in symptomatic hypotension (3.2%). The use of intravenous diltiazem for control of ventricular response in patients with supraventricular arrhythmias should be undertaken with caution when the patient is compromised hemodynamically. In addition, caution should be used in patients taking other drugs that decrease peripheral resistance, intravascular volume, myocardial contractility or conduction. 4.

Acute Hepatic

Injury - In rare instances, significant elevations in enzymes such as alkaline phosphatase, LDH, SGOT, SGPT, and other phenomena consistent with acute hepatic injury have been noted following oral diltiazem. Therefore, the potential for acute hepatic injury exists following administration of intravenous diltiazem. 5.

Ventricular Premature

Beats (VPBs) - VPBs may be present on conversion of PSVT to sinus rhythm with diltiazem hydrochloride injection. These VPBs are transient, are typically considered to be benign, and appear to have no clinical significance. Similar ventricular complexes have been noted during cardioversion, other pharmacologic therapy, and during spontaneous conversion of PSVT to sinus rhythm.

PRECAUTIONS General Diltiazem hydrochloride is extensively metabolized by the liver and excreted by the kidneys and in bile. The drug should be used with caution in patients with impaired renal or hepatic function (see WARNINGS ). High intravenous dosages (4.5 mg/kg tid) administered to dogs resulted in significant bradycardia and alterations in AV conduction. In subacute and chronic dog and rat studies designed to produce toxicity, high oral doses of diltiazem were associated with hepatic damage. In special subacute hepatic studies, oral doses of 125 mg/kg and higher in rats were associated with histological changes in the liver, which were reversible when the drug was discontinued. In dogs, oral doses of 20 mg/kg were also associated with hepatic changes; however, these changes were reversible with continued dosing. Dermatologic events progressing to erythema multiforme and/or exfoliative dermatitis have been infrequently reported following oral diltiazem. Therefore, the potential for these dermatologic reactions exists following exposure to intravenous diltiazem. Should a dermatologic reaction persist, the drug should be discontinued.

Drug

Interactions 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 P-450 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. A nesthetics - 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 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 - Intravenous diltiazem has been administered to patients on chronic oral beta-blocker therapy. The combination of the two drugs was generally well tolerated without serious adverse effects. If intravenous diltiazem is administered to patients receiving chronic oral beta-blocker therapy, the possibility for bradycardia, AV block, and/or depression of contractility should be considered (see CONTRAINDICATIONS ). Oral administration of diltiazem 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. 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 oral diltiazem with carbamazepine has been reported to result in elevated plasma levels of carbamazepine (by 40 to 72%), 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 1,200 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 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. Cyclosporine - A pharmacokinetic interaction between diltiazem and cyclosporine has been observed during studies involving renal and cardiac transplant patients. In renal and cardiac transplant recipients, a reduction of cyclosporine dose ranging from 15% to 48% was necessary to maintain cyclosporine trough concentrations similar to those seen prior to the addition of diltiazem. If these agents are to be administered concurrently, cyclosporine concentrations should be monitored, especially when diltiazem therapy is initiated, adjusted or discontinued. The effect of cyclosporine on diltiazem plasma concentrations has not been evaluated. Digitalis - Intravenous diltiazem has been administered to patients receiving either intravenous or oral digitalis therapy. The combination of the two drugs was well tolerated without serious adverse effects. However, since both drugs affect AV nodal conduction, patients should be monitored for excessive slowing of the heart rate and/or AV block. Ivabradine - Concurrent use of diltiazem increases exposure to ivabradine and may exacerbate bradycardia and conduction disturbances. Avoid concomitant use of ivabradine and diltiazem. Quinidine - Diltiazem significantly increases the AUC (0→∞) of quinidine by 51%, T 1/2 by 36% and decreases its CL oral , by 33%. Monitoring for quinidine adverse effects may be warranted and the dose adjusted accordingly. Rifampin - Coadministration of rifampin with diltiazem lowered the diltiazem plasma concentrations to undetectable levels. Coadministration of diltiazem with rifampin or any known CYP3A4 inducer should be avoided when possible, and alternative therapy considered. 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 together 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), coadministration of a single 20 mg dose of simvastatin at the end of a 14 day regimen with 120 mg BID diltiazem SR resulted in a 5-fold increase in mean simvastatin AUC versus simvastatin alone. Subjects with increased average steady-state exposures of diltiazem showed a greater fold increase in simvastatin exposure. Computer-based simulations showed that at a daily dose of 480 mg of diltiazem, an 8- to 9-fold mean increase in simvastatin AUC can be expected. If coadministration 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 crossover study, coadministration of diltiazem (120 mg bid, diltiazem SR for 2 weeks) with a single 20 mg dose of lovastatin resulted in a 3- to 4-fold increase in mean lovastatin AUC and C max versus lovastatin alone. In the same study, there was no significant change in 20 mg single dose pravastatin AUC and C max during diltiazem coadministration. Diltiazem plasma levels were not significantly affected by lovastatin or pravastatin. Carcinogenesis, Mutagenesis, Impairment of Fertility A 24-month study in rats at oral dosage levels of up to 100 mg/kg/day and a 21-month study in mice at oral dosage levels of up to 30 mg/kg/day showed no evidence of carcinogenicity. There was also no mutagenic response in vitro or in vivo in mammalian cell assays or in vitro in bacteria. No evidence of impaired fertility was observed in a study performed in male and female rats at oral dosages of up to 100 mg/kg/day.

Pregnancy

Reproduction studies have been conducted in mice, rats, and rabbits. Administration of oral doses ranging from five to ten times greater (on a mg/kg basis) than the daily recommended oral antianginal therapeutic dose has resulted in embryo and fetal lethality. These doses, in some studies, have been reported to cause skeletal abnormalities. In the perinatal/postnatal studies there was some reduction in early individual pup weights and survival rates. There was an increased incidence of stillbirths at doses of 20 times the human oral antianginal dose or greater. There are no well-controlled studies in pregnant women; therefore, use diltiazem hydrochloride in pregnant women only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers

Diltiazem is excreted in human milk. One report with oral diltiazem suggests that concentrations in breast milk may approximate serum levels. If use of diltiazem hydrochloride is deemed essential, an alternative method of infant feeding should be instituted.

Pediatric Use

Safety and effectiveness in pediatric patients have not been established.

Geriatric Use

Clinical studies of diltiazem did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. Atrial fibrillation or atrial flutter - In clinical studies with diltiazem hydrochloride injection for AF/FI, 135 of 257 patients were ↑65 years of age. No overall differences in safety or effectiveness were observed between these patients and younger patients, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out. In subgroup analysis of double-blind and open-label trials following first-dose response, 116 patients ↑65 years of age had a response rate of 84%. One hundred two (102) patients <65 had a response rate of 78%. In subgroup analysis following a two-dose procedure in double-blind and open-label studies, 104 patients ↑65 years of age and 95 patients <65 both had a 95% response rate. Paroxysmal supraventricular tachycardia - Clinical studies of diltiazem hydrochloride injection for PSVT did not include sufficient numbers of patients aged 65 and over to determine whether they respond differently from younger patients. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. Diltiazem hydrochloride is extensively metabolized by the liver and excreted by the kidneys and in bile. The risk of toxic reactions to this drug may be greater in patients with impaired renal or hepatic function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function. As with all drugs, care should be exercised when treating patients with multiple medications (see PRECAUTIONS , General and Drug Interactions ).

Drug Interactions Because of the potential for additive effects, slow titration is warranted in patients receiving diltiazem hydrochloride concomitantly with other 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 CARDIZEM CD (see WARNINGS ). Diltiazem is both a substrate and an inhibitor of the Pg-p and cytochrome P450 3A4 enzyme system which may affect exposure to diltiazem and concomitant drugs metabolized by those pathways. Patients with renal and/or hepatic impairment may be particularly at risk of exposure changes. 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, titrate anesthetics and calcium blockers slowly. 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, 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 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. Cimetidine: A study in six healthy volunteers has shown a significant increase in peak diltiazem plasma levels (58%) and AUC (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 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. Cyclosporine: A pharmacokinetic interaction between diltiazem and cyclosporine has been observed during studies involving renal and cardiac transplant patients. In renal and cardiac transplant recipients, a reduction of cyclosporine dose ranging from 15% to 48% was necessary to maintain cyclosporine trough concentrations similar to those seen prior to the addition of diltiazem. If these agents are to be administered concurrently, cyclosporine concentrations should be monitored, especially when diltiazem therapy is initiated, adjusted, or discontinued. The effect of cyclosporine on diltiazem plasma concentrations has not been evaluated. 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. Monitor digoxin levels when initiating, adjusting, and discontinuing diltiazem hydrochloride therapy to avoid possible over- or under-digitalization (see WARNINGS ). Ivabradine: Concurrent use of diltiazem increases exposure to ivabradine and may exacerbate bradycardia and conduction disturbances. Avoid concomitant use of ivabradine and diltiazem. Quinidine: Diltiazem significantly increases the AUC (0-∞) of quinidine by 51%, T 1/2 by 36%, and decreases its CL oral by 33%. Monitor for quinidine adverse effects and adjust the dose accordingly. Rifampin: Coadministration of rifampin with diltiazem lowered the diltiazem plasma concentrations to undetectable levels. Avoid coadministration of diltiazem with rifampin or any known CYP3A4 inducer. 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 together with diltiazem; otherwise, monitor for signs and symptoms of any statin-related adverse events, and adjust the doses accordingly. In a healthy volunteer crossover study (N=10), coadministration of a single 20 mg dose of simvastatin at the end of a 14-day regimen with 120 mg BID diltiazem SR resulted in a 5-fold increase in mean simvastatin AUC versus simvastatin alone. Subjects with increased average steady-state exposures of diltiazem showed a greater fold increase in simvastatin exposure. Computer-based simulations showed that at a daily dose of 480 mg of diltiazem, an 8- to 9-fold mean increase in simvastatin AUC can be expected. If coadministration 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 crossover study, coadministration of diltiazem (120 mg BID diltiazem SR for 2 weeks) with a single 20 mg dose of lovastatin resulted in 3- to 4-fold increase in mean lovastatin AUC and C max versus lovastatin alone. In the same study, there was no significant change in 20 mg single dose pravastatin AUC and C max during diltiazem coadministration. Diltiazem plasma levels were not significantly affected by lovastatin or pravastatin. Alcohol: Alcohol increases the rate at which CARDIZEM CD releases diltiazem in vitro. This effect may lead to more rapid absorption and an increase in the systemic exposure of diltiazem, and associated dose-related adverse reactions. Avoid consumption of alcohol with CARDIZEM CD (see CLINICAL PHARMACOLOGY ). Carcinogenesis, Mutagenesis, Impairment of Fertility A 24-month study in rats at oral dosage levels of up to 100 mg/kg/day and a 21-month study in mice at oral dosage levels of up to 30 mg/kg/day showed no evidence of carcinogenicity. There was also no mutagenic response in vitro or in vivo in mammalian cell assays or in vitro in bacteria. No evidence of impaired fertility was observed in a study performed in male and female rats at oral dosages of up to 100 mg/kg/day.

Pregnancy

Reproduction studies have been conducted in mice, rats, and rabbits. Administration of doses ranging from five to ten times greater (on a mg/kg basis) than the daily recommended therapeutic dose has resulted in embryo and fetal lethality. These doses, in some studies, have been reported to cause skeletal abnormalities. In the perinatal/postnatal studies, there was an increased incidence of stillbirths at doses of 20 times the human dose or greater. There are no well-controlled studies in pregnant women; therefore, use diltiazem hydrochloride in pregnant women only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers

Diltiazem is excreted in human milk. One report suggests that concentrations in breast milk may approximate serum levels. If use of CARDIZEM CD is deemed essential, an alternative method of infant feeding should be instituted.

Pediatric Use

Safety and effectiveness in pediatric patients have not been established.

Geriatric Use

Clinical studies of diltiazem did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.