Pregnancy Risk Category C
How supplied
Tablets: 30 mg, 60 mg, 90 mg, 120 mg
Capsules (extended-release; Cardizem CD, Dilacor XR, Tiazac): 120 mg, 180 mg, 240 mg, 300 mg, 360 mg (Tiazac)
Capsules (sustained-release; Cardizem SR): 60 mg, 90 mg, 120 mg, 180 mg, 240 mg
Injection: 5 mg/ml
Action
A calcium channel blocker that inhibits calcium ion influx across cardiac and smooth-muscle cells, decreasing myocardial contractility and oxygen demand. Also dilates coronary arteries and arterioles.
Indications & dosage
Vasospastic angina (Prinzmetal's or variant angina), classic chronic stable angina pectoris--
Adults: 30 mg P.O. t.i.d. or q.i.d. before meals and h.s., increased gradually to maximum of 360 mg daily in divided doses. Or, 120 or 180 mg (extended-release). Adjusted as needed and tolerated to maximum of 480 mg daily.
Hypertension--
Adults: 60 to 120 mg P.O. b.i.d.
(sustained-release). Adjusted to effect. Maximum dose is 360 mg daily. Or, initially 180 to 240 mg daily (extended-release). Dosage adjusted, p.r.n.
Atrial fibrillation or flutter, paroxysmal supraventricular tachycardia--
Adults: 0.25 mg/kg as an I.V. bolus injection over 2 minutes. If response is inadequate, 0.35 mg/kg I.V. after 15 minutes followed by a continuous infusion of 10 mg/hour. Some patients respond well to a rate of 5 mg/hour; maximum dose is 15 mg/hour.
Adverse reactions
CNS: headache, dizziness, asthenia, somnolence.
CV: edema, arrhythmias, flushing, bradycardia, hypotension, conduction abnormalities, heart failure, AV block, abnormal ECG.
GI: nausea, constipation, abdominal discomfort.
Hepatic: acute hepatic injury.
Skin: rash.
Interactions
Drug-drug. Anesthetics: effects may be potentiated. Monitor patient.
Carbamazepine: increased levels of carbamazepine. Monitor carbamazepine levels and watch for signs and symptoms of toxicity.
Cimetidine: may inhibit diltiazem metabolism. Monitor for toxicity, additive AV node conduction slowing.
Cyclosporine: diltiazem may increase serum cyclosporine levels, possibly by decreasing its metabolism, leading to increased risk of cyclosporine toxicity. If used concurrently, monitor cyclosporine levels.
Digoxin: diltiazem may increase serum levels of digoxin. Monitor for toxicity.
Furosemide: forms a precipitate when mixed with diltiazem injection. Administer through separate I.V. lines.
Propranolol, other beta blockers: may precipitate heart failure or prolong conduction time. Use together cautiously.
Effects on diagnostic tests
None reported.
Contraindications
Contraindicated in patients with hypersensitivity to drug, sick sinus syndrome or second- or third-degree AV block in the absence of an artificial pacemaker, systolic blood pressure below 90 mm Hg, acute MI, or pulmonary congestion (documented by X-ray).
Nursing considerations
I.V. administration
Patient teaching
*Liquid contains alcohol. **May contain tartrazine. †Canada ‡Australia §U.K. OTCOver the counter
Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE-THREATENING