DILTIAZEM
(dil-tye'a-zem)
Cardizem, Cardizem CD, Cardizem LA, Cardizem SR, Cardizem Lyo-Ject, Cartia XT, Dilacor XR, Tiamate, Tiazac, Taztia XT
DILTIAZEM IV
Cardizem IV
Classifications: cardiovascular agent; calcium channel blocking agent; antihypertensive
Prototype: Verapamil
Pregnancy Category: C

Availability

30 mg, 60 mg, 90 mg, 120 mg tablets; 120 mg, 180 mg, 240 mg sustained-release tablets; 60 mg, 90 mg, 120 mg, 180 mg, 240 mg, 300 mg, 360 mg sustained-release capsules; 120 mg, 180 mg, 240 mg, 300 mg, 360 mg, 420 mg extended-release tablets; 25 mg, 50 mg vials

Actions

Slow channel blocker with pharmacologic actions similar to those of verapamil. Inhibits calcium ion influx through slow channels into cell of myocardial and arterial smooth muscle (both coronary and peripheral blood vessels). As a result, intracellular calcium remains at subthreshold levels insufficient to stimulate cell excitation and contraction. Slows SA and AV node conduction (antiarrhythmic effect) without affecting normal arterial action potential or intraventricular conduction.

Therapeutic Effects

Dilates coronary arteries and arterioles and inhibits coronary artery spasm; thus myocardial oxygen delivery is increased (antianginal effect). By vasodilation of peripheral arterioles, drug decreases total peripheral vascular resistance and reduces arterial BP at rest (antihypertensive effect).

Uses

Vasospastic angina (Prinzmetal's variant or at rest angina), chronic stable (classic effort-associated) angina, essential hypertension. IV form: Atrial fibrillation, atrial flutter, supraventricular tachycardia.

Unlabeled Uses

Prevention of reinfarction in non-Q-wave MI.

Contraindications

Known hypersensitivity to drug; sick sinus syndrome (unless pacemaker is in place and functioning); second- or third-degree AV block; severe hypotension (systolic <90 mm Hg or diastolic <60 mm Hg); patients undergoing intracranial surgery; bleeding aneurysms. Safe use during pregnancy (category C), lactation, or in children is not established.

Cautious Use

CHF (especially if patient is also receiving beta blocker), conduction abnormalities; renal or hepatic impairment; older adults.

Route & Dosage

Angina
Adult: PO 30 mg q.i.d., may increase q1–2d as required (usual range: 180–360 mg/d in divided doses)

Hypertension
Adult: PO 60–120 mg sustained-release b.i.d. (usual range: 240–360 mg/d) or 120–540 mg of CD or LA once daily

Atrial Fibrillation
Adult: IV 0.25 mg/kg IV bolus over 2 min, if inadequate response, may repeat in 15 min with 0.35 mg/kg, followed by a continuous infusion of 5–10 mg/h (max: 15 mg/h for 24 h)

Administration

Oral

Do not crush sustained-release capsules or tablets. They must be swallowed whole.
Withhold if systolic BP is <90 mm Hg or diastolic is <60 mm Hg.
Give before meals and at bedtime.
Store at 15°–30° C (59°–86° F).

Intravenous

PREPARE: Direct: Give undiluted. Continuous: For IV infusion, add to a volume of D5W, NS, or D5/0.45% NaCl that can be administered in 24 h or less.

ADMINISTER: Direct: Give as a bolus dose over 2 min. A second bolus may be given after 15 min. Continuous: Give at a rate 5–15 mg/h. Infusion duration longer than 24 h and infusion rate >15 mg/h are not recommended.

INCOMPATIBILITIES Solution/additive: Furosemide. Y-site: Furosemide.

Adverse Effects (1%)

CNS: Headache, fatigue, dizziness, asthenia, drowsiness, nervousness, insomnia, confusion, tremor, gait abnormality. CV: Edema, arrhythmias, angina, second- or third-degree AV block, bradycardia, CHF, flushing, hypotension, syncope, palpitations. GI: Nausea, constipation, anorexia, vomiting, diarrhea, impaired taste, weight increase. Skin: Rash.

Interactions

Drug: beta blockers, digoxin may have additive effects on av node conduction prolongation; may increase digoxin or quinidine levels; cimetidine may increase diltiazem levels, thus increasing effects; may increase cyclosporine levels.

Pharmacokinetics

Absorption: Approximately 80% absorbed from GI tract, with 40% reaching systemic circulation. Peak: 2–3 h; 6–11 h sustained release; 11–18 h Cardizem LA. Distribution: Distributed into breast milk. Metabolism: Metabolized in liver. Elimination: Excreted primarily in urine with some elimination in feces. Half-Life: Oral 3.5–9 h, IV 2 h.

Nursing Implications

Assessment & Drug Effects

Check BP and ECG before initiation of therapy and monitor particularly during dosage adjustment period.
Lab tests: Do baseline and periodic liver and renal function tests.
Monitor for and report S&S of CHF.
Monitor for headache. An analgesic may be required.
Supervise ambulation as indicated.

Patient & Family Education

Make position changes slowly and in stages; light-headedness and dizziness (hypotension) are possible.
Do not drive or engage in other potentially hazardous activities until reaction to drug is known.
Keep follow-up appointments and physician informed.
Do not breast feed while taking this drug without consulting physician.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug