Home Drug Guide Diltiazem Malate

Drug Guide

Generic Name

Diltiazem Malate

Brand Names Tiamate

Classification

Therapeutic: Antihypertensive, Antianginal

Pharmacological: Calcium Channel Blocker

FDA Approved Indications

Hypertension
Chronic stable angina pectoris
Vasospastic angina (Prinzmetal's angina)

Mechanism of Action

Diltiazem inhibits calcium ions from entering vascular smooth muscle and cardiac cells, causing relaxation of coronary and peripheral arteries, reducing myocardial oxygen demand, and decreasing blood pressure.

Dosage and Administration

Adult: Typically 180-240 mg per day in divided doses, adjusted based on clinical response.

Pediatric: Not approved for pediatric use without specialist consultation.

Geriatric: Use with caution; start at lower doses due to increased risk of hypotension and adverse reactions.

Renal Impairment: Adjust dose in severe impairment; closely monitor blood pressure and cardiac function.

Hepatic Impairment: Use with caution; start at lower doses and titrate carefully.

Pharmacokinetics

Absorption: Well absorbed orally; approximately 40-50% bioavailability due to first-pass metabolism.

Distribution: Extensive protein binding (~80%).

Metabolism: Hepatic via CYP3A4; undergoes extensive first-pass metabolism.

Excretion: Primarily excreted in urine (about 60%), with some eliminated in feces.

Half Life: 3 to 4.5 hours; extended-release formulations may vary.

Contraindications

Hypersensitivity to diltiazem or other calcium channel blockers
Idiopathic ventricular tachycardia
Sick sinus syndrome without a pacemaker
2nd or 3rd degree AV block

Precautions

Heart failure, hypotension, severe hepatic impairment, ventricular hypertrophy, recent myocardial infarction

Adverse Reactions - Common

Headache (Common)
Dizziness (Common)
Peripheral edema (Common)
Flushing (Common)

Adverse Reactions - Serious

Bradycardia (Uncommon)
AV block (Uncommon)
Heart failure exacerbation (Uncommon)
Liver enzyme elevation (Rare)

Drug-Drug Interactions

Beta-blockers (additive effect on cardiac depression)
Grapefruit juice (increases diltiazem levels)
CYP3A4 inhibitors (potentiate effects)

Drug-Food Interactions

Grapefruit juice

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor blood pressure, heart rate, and ECG for rhythm changes; assess for signs of heart failure.

Diagnoses:

Risk for decreased cardiac output
Risk for hypotension

Implementation: Administer with food to reduce gastrointestinal upset; monitor vital signs; educate patient on orthostatic hypotension.

Evaluation: Observe for reduction in anginal episodes, blood pressure control, and adverse reactions.

Patient/Family Teaching

Take medication exactly as prescribed; do not discontinue abruptly.
Report swelling, shortness of breath, or irregular heartbeat.
Avoid grapefruit juice and alcohol.
Rise slowly from sitting or lying positions to prevent falls.

Special Considerations

Black Box Warnings:

None specific, but caution advised in heart failure and significant conduction system disease.

Genetic Factors: Cytochrome P450 metabolism may influence drug levels; pharmacogenetic testing not routine.

Lab Test Interference: May cause alterations in liver function tests and blood counts.

Overdose Management

Signs/Symptoms: Severe hypotension, bradycardia, AV block, conduction failure, cardiogenic shock.

Treatment: Supportive therapy, intravenous calcium, vasopressors if needed; atropine for bradycardia; dialysis generally not effective.

Storage and Handling

Storage: Store at room temperature, away from light and moisture.

Stability: Stable until expiration date on package.