DILTIAZEM

DILTIAZEM
(dil-tye'a-zem)
Cardizem, Cardizem CD, Cardizem LA, Cartia XT, Dilacor XR, Tiazac, Taztia XT
DILTIAZEM IV
Cardizem IV
Classifications: calcium channel blocking agent; antianginal; antihypertensive;
Therapeutic: antihypertensive; antianginal; antiarrhythmic
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

Action

Inhibits calcium ion influx through slow channels into cell of myocardial and arterial smooth muscle (both coronary and peripheral blood vessels). Improves myocardial perfusion, and reduces left ventricular workload.

Therapeutic Effect

Slows SA and AV node conduction (antiarrhythmic effect). 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); acute MI; CHF; left ventricular dysfunction; second- or third-degree AV block, Wolff-Parkinson-White syndrome, Lown-Ganong-Levine syndrome; severe hypotension (systolic <90 mm Hg or diastolic <60 mm Hg); patients undergoing intracranial surgery; bleeding aneurysms; pregnancy (category C). Safe use in children is not established.

Cautious Use

Sinoatrial nodal dysfunction, sick sinus syndrome; right ventricular dysfunction, severe bradycardia; 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: Acetazolamide, acyclovir, aminophylline, ampicillin, ampicillin/sulbactam, cefoperazone, diazepam, furosemide, hydrocortisone, insulin, methylprednisolone, mezlocillin, nafcillin, phenytoin, rifampin, sodium bicarbonate, thiopental.

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: Into breast milk. Metabolism: In liver (CYP3A4). Elimination: 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.

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

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