Diltiazem

Diltiazem hydrochloride extended-release capsules are indicated for the treatment of hypertension. It may be used alone or in combination with other antihypertensive medications. Diltiazem hydrochloride extended-release capsules are indicated for the management of chronic stable angina and angina due to coronary artery spasm.

• Patients controlled on diltiazem alone or in combination with other medications may be switched to diltiazem hydrochloride extended-release capsules, USP at the nearest equivalent total daily dose
• Higher doses of diltiazem hydrochloride extended-release capsules, USP may be needed in some patients
• Monitor patients closely
• Subsequent titration to higher or lower doses may be necessary
• There is limited general clinical experience with doses above 360 mg, but doses to 540 mg have been studied in clinical trials
• The incidence of side effects increases as the dose increases with first-degree AV block, dizziness, and sinus bradycardia bearing the strongest relationship to dose
• Hypertension : Adjust dosage to individual patient needs
• When used as monotherapy, reasonable starting doses are 180 to 240 mg once daily, although some patients may respond to lower doses
• Maximum antihypertensive effect is usually observed by 14 days of chronic therapy; therefore, schedule dosage adjustments accordingly
• The usual dosage range studied in clinical trials was 240 to 360 mg once daily
• Individual patients may respond to higher doses of up to 480 mg once daily
• Angina : Dosages
• For the treatment of angina should be adjusted to each patient's needs, starting with a dose of 120 or 180 mg once daily
• Individual patients may respond to higher doses of up to 480 mg once daily

• Safety and effectiveness
• In pediatric patients have not been established

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. …

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 mm Hg systolic), (4) patients who have demonstrated hypersensitivity to the drug, and (5) patients with acute myocardial infarction and pulmonary congestion documented by x-ray on admission.

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 diltiazem hydrochloride (see WARNINGS ). 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. …

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 3290 patients or 0.40%). 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 (see 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 have usually been excluded from these studies. The following table presents the most common adverse reactions reported in placebo-controlled angina and hypertension trials in patients receiving diltiazem hydrochloride extended-release capsules up to 360 mg with rates in placebo patients shown for comparison. In addition, the following events were reported infrequently (less than 1%) in angina or hypertension trials: Cardiovascular: Congestive heart failure, palpitations, syncope, ventricular extrasystoles. …

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. …

The oral LD 50 s in mice and rats range from 415 to 740 mg/kg and from 560 to 810 mg/kg, respectively. The intravenous LD 50 s in these species were 60 and 38 mg/kg, respectively. The oral LD 50 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. Because of its 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

Take it when you remember, unless it is nearly time for the next dose. Then skip the missed one. Never take two doses at once to make up for it. Check your leaflet, as some medicines are different.