Generic Name

Diltiazem Hydrochloride

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Classification

FDA Approved Indications

• Hypertension
• Angina pectoris (chronic stable angina, vasospastic angina)
• Chronic stable angina in certain cases

Mechanism of Action

Diltiazem inhibits calcium ion influx into vascular smooth muscle and cardiac muscle, leading to dilation of coronary and peripheral arteries, reducing cardiac contractility, and decreasing myocardial oxygen demand.

Dosage and Administration

Adult: Typically 180-420 mg daily in divided doses or once daily in sustained-release forms, titrated based on response.

Pediatric: Use not generally recommended; consult specialist for pediatric use.

Geriatric: Start at lower dose due to increased sensitivity and risk of hypotension.

Renal Impairment: Adjust dose cautiously; monitor blood pressure and heart rate.

Hepatic Impairment: Use with caution; dose adjustment may be necessary, as drug metabolism may be impaired.

Pharmacokinetics

Absorption: Well absorbed orally with peak plasma levels in 2-4 hours.

Distribution: Widely distributed; moderate protein binding (~90%).

Metabolism: Extensively metabolized in the liver via CYP3A4.

Excretion: Primarily via feces; small amount excreted in urine.

Half Life: 3-7 hours for immediate-release; longer for extended-release formulations.

Contraindications

• Severe hypotension
• 2nd or 3rd degree AV block (without pacemaker)
• Acute myocardial infarction with pump failure

Precautions

• Use cautiously in heart failure, hepatic impairment, and in patients on beta-blockers.

Adverse Reactions - Common

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

Adverse Reactions - Serious

• Bradycardia (Serious)
• AV block (heart block) (Serious)
• Hypotension (Serious)
• Worsening heart failure (Serious)

Drug-Drug Interactions

• Beta-blockers (additive effect on heart rate and contractility)
• Digoxin (may increase levels)
• CYP3A4 inhibitors or inducers (alter metabolism)

Drug-Food Interactions

• Grapefruit juice (increases plasma levels)

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Take medication exactly as prescribed.
• Do not stop abruptly to avoid precipitating angina or hypertension.
• Report signs of swelling, dizziness, slow heartbeat, or chest pain.
• Limit grapefruit juice to reduce interaction risk.

Special Considerations

Black Box Warnings:

• May cause or exacerbate heart failure in some patients.
• Use cautiously in patients with conduction abnormalities.

Genetic Factors: CYP3A4 polymorphisms may affect metabolism.

Lab Test Interference: May alter liver function tests; monitor accordingly.

Overdose Management

Signs/Symptoms: Severe bradycardia, hypotension, AV block, cardiogenic shock, and potentially death.

Treatment: Supportive care, activated charcoal if ingestion recent, calcium gluconate IV for calcium channel blocker overdose, vasopressors, and pacing if needed.

Storage and Handling

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

Stability: Stable under recommended storage conditions.