Diltiazem Hydrochloride 120 mg Capsule, Extended Release, 30-count

WARNINGS 1. Cardiac Conduction: Diltiazem hydrochloride prolongs AV node refractory periods without significantly prolonging sinus node recovery time, except in patients with sick sinus syndrome. This effect may rarely result in abnormally slow heart rates (particularly in patients with sick sinus syndrome) or second- or third-degree AV block (13 of 3007 patients or 0.43%).

Concomitant use of diltiazem with beta-blockers or digitalis may result in additive effects on cardiac conduction. A patient with Prinzmetal's angina developed periods of asystole (2 to 5 seconds) after a single dose of 60 mg of diltiazem. 2.

Congestive Heart Failure: Although diltiazem has a negative inotropic effect in isolated animal tissue preparations, hemodynamic studies in humans with normal ventricular function have not shown a reduction in cardiac index nor consistent negative effects on contractility (dP/dt). An acute study of oral diltiazem in patients with impaired ventricular function (ejection fraction 24% ± 6%) showed improvement in indices of ventricular function without significant decrease in contractile function (dP/dt). Worsening of congestive heart failure has been reported in patients with preexisting impairment of ventricular function.

Experience with the use of diltiazem hydrochloride in combination with beta-blockers in patients with impaired ventricular function is limited. Caution should be exercised when using this combination. 3.

Hypotension: Decreases in blood pressure associated with diltiazem hydrochloride therapy may occasionally result in symptomatic hypotension. 4. Acute Hepatic Injury: Mild elevations of transaminases with and without concomitant elevation in alkaline phosphatase and bilirubin have been observed in clinical studies.

Such elevations were usually transient and frequently resolved even with continued diltiazem treatment. In rare instances, significant elevations in enzymes such as alkaline phosphatase, LDH, SGOT, and SGPT, and other phenomena consistent with acute hepatic injury have been noted. These reactions tended to occur early after therapy initiation (1 to 8 weeks) and have been reversible upon discontinuation of drug therapy.

The relationship to diltiazem hydrochloride is uncertain in some cases but probable in some (see PRECAUTIONS ).

ADVERSE REACTIONS Serious adverse reactions have been rare in studies with diltiazem, as well as with other diltiazem formulations. It should be recognized that patients with impaired ventricular function and cardiac conduction abnormalities have usually been excluded from these studies. A total of 256 hypertensives were treated for between 4 and 8 weeks; a total of 207 patients with chronic stable angina were treated for 3 weeks with doses of diltiazem ranging from 120 to 540 mg once daily.

Two patients experienced first-degree AV block at the 540 mg dose. The following table presents the most common adverse reactions, whether or not drug-related, reported in placebo-controlled trials in patients receiving diltiazem up to 360 mg and up to 540 mg with rates in placebo patients shown for comparison. MOST COMMON ADVERSE EVENTS IN DOUBLE-BLIND PLACEBO-CONTROLLED HYPERTENSION TRIALS * Placebo Diltiazem Adverse Events (COSTART Term) n=57 # pts (%) Up to 360 mg n=149 # pts (%) 480 to 540 mg n=48 # pts (%) edema, peripheral 1 (2) 8 (5) 7 (15) dizziness 4 (7) 6 (4) 2 (4) vasodilation 1 (2) 5 (3) 1 (2) dyspepsia 0 (0) 7 (5) 0 (0) pharyngitis 2 (4) 3 (2) 3 (6) rash 0 (0) 3 (2) 0 (0) infection 2 (4) 2 (1) 3 (6) diarrhea 0 (0) 2 (1) 1 (2) palpitations 0 (0) 2 (1) 1 (2) nervousness 0 (0) 3 (2) 0 (0) * Adverse events occurring in treated patients at 2% or more than placebo-treated patients.

MOST COMMON ADVERSE EVENTS IN DOUBLE-BLIND PLACEBO-CONTROLLED ANGINA TRIALS* Placebo Diltiazem Adverse Events (COSTART Term) n=50 # pts (%) Up to 360 mg n=158 # pts (%) 540 mg n=49 # pts (%) headache 1 (2) 13 (8) 4 (8) edema, peripheral 1 (2) 3 (2) 5 (10) pain 1 (2) 10 (6) 3 (6) dizziness 0 (0) 5 (3) 5 (10) asthenia 0 (0) 1 (1) 2 (4) dyspepsia 0 (0) 2 (1) 3 (6) dyspnea 0 (0) 1 (1) 3 (6) bronchitis 0 (0) 1 (1) 2 (4) AV block 0 (0) 0 (0) 2 (4) infection 0 (0) 2 (1) 1 (2) flu syndrome 0 (0) 0 (0) 1 (2) cough increase 0 (0) 2 (1) 1 (2) extrasystoles 0 (0) 0 (0) 1 (2) gout 0 (0) 2 (1) 1 (2) myalgia 0 (0) 0 (0) 1 (2) impotence 0 (0) 0 (0) 1 (2) conjunctivitis 0 (0) 0 (0) 1 (2) rash 0 (0) 2 (1) 1 (2) abdominal enlargement 0 (0) 0 (0) 1 (2) * Adverse events occurring in treated patients at 2% or more than placebo-treated patients.

In addition, the following events have been reported infrequently (less than 2%) in clinical trials with other diltiazem products: Cardiovascular: Angina, arrhythmia, AV block (second- or third-degree), bundle branch block, congestive heart failure, ECG abnormalities, hypotension, palpitations, syncope, tachycardia, ventricular extrasystoles. Nervous System: Abnormal dreams, amnesia, depression, gait abnormality, hallucinations, insomnia, nervousness, paresthesia, personality change, somnolence, tinnitus, tremor. Gastrointestinal: Anorexia, constipation, diarrhea, dry mouth, dysgeusia, mild elevations of SGOT, SGPT, LDH, and alkaline phosphatase (see WARNINGS, Acute Hepatic Injury ), nausea, thirst, vomiting, weight increase.

Dermatological: Petechiae, photosensitivity, pruritus. Other: Albuminuria, allergic reaction, amblyopia, asthenia, CPK increase, crystalluria, dyspnea, edema, epistaxis, eye irritation, headache, hyperglycemia, hyperuricemia, impotence, muscle cramps, nasal congestion, neck rigidity, nocturia, osteoarticular pain, pain, polyuria, rhinitis, sexual difficulties, gynecomastia. In addition, the following postmarketing events have been reported infrequently in patients receiving diltiazem hydrochloride: acute generalized exanthematous pustulosis, alopecia, erythema multiforme, exfoliative dermatitis, Stevens-Johnson syndrome, toxic epidermal necrolysis, extrapyramidal symptoms, gingival hyperplasia, hemolytic anemia, increased bleeding time, photosensitivity (including lichenoid keratosis and hyperpigmentation at sun-exposed skin areas), leukopenia, purpura, retinopathy, and thrombocytopenia.

In addition, events such as myocardial infarction have been observed which are not readily distinguishable from the natural hist…

Drug Interactions Due to the potential for additive effects, caution and careful titration are 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 diltiazem (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 the 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 channel 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, 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 ½ 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 AUC (53%) after a 1-week course of cimetidine 1200 mg/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 wa…