Generic Name

Isosorbide Dinitrate

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Classification

FDA Approved Indications

• Angina pectoris

Mechanism of Action

Isosorbide Dinitrate relaxes vascular smooth muscle by releasing nitric oxide, which stimulates guanylate cyclase to increase cyclic GMP levels, leading to vasodilation. This reduces myocardial oxygen demand and alleviates anginal symptoms.

Dosage and Administration

Adult: Typically 5-40 mg 3-4 times daily, taken on an empty stomach. Dose titration based on response.

Pediatric: Use is not generally approved for pediatric patients; consult specific clinical guidelines.

Geriatric: Start at lower end of dosing range; monitor for hypotension and tolerance.

Renal Impairment: Use cautious dosing; may require dose adjustments.

Hepatic Impairment: Use with caution; liver function impairment may affect drug metabolism.

Pharmacokinetics

Absorption: Well absorbed orally, subject to first-pass metabolism.

Distribution: Distributed widely in body tissues.

Metabolism: Primarily hepatic via conjugation and oxidation.

Excretion: Excreted mainly in urine as metabolites.

Half Life: 1-4 hours for immediate-release; longer for sustained-release formulations.

Contraindications

• Hypersensitivity to nitrates
• Concurrent use with phosphodiesterase inhibitors (e.g., sildenafil)

Precautions

• Use with caution in hypotension, increased intracranial pressure, anemia, or known glaucoma. Tolerance may develop with continuous use. Use during pregnancy only if clearly needed; data are limited.

Adverse Reactions - Common

• Headache (Very common)
• Dizziness (Common)
• Flushing (Common)
• Orthostatic hypotension (Uncommon)

Adverse Reactions - Serious

• Reflex tachycardia (Uncommon)
• Methemoglobinemia (rare) (Rare)

Drug-Drug Interactions

• Other antihypertensives, alcohol, phosphodiesterase inhibitors

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Take medication exactly as prescribed.
• Be aware of possible headache and dizziness. Avoid driving if dizzy.
• Report any signs of severe headache, hypotension, or allergic reactions.
• Do not switch formulations without consulting healthcare provider.

Special Considerations

Black Box Warnings:

• None specific for Isosorbide Dinitrate.

Genetic Factors: Nitrate tolerance may develop more rapidly in some individuals.

Lab Test Interference: No significant interference noted.

Overdose Management

Signs/Symptoms: Severe hypotension, tachycardia, dizziness, fainting.

Treatment: Discontinue drug immediately. Supportive care including intravenous fluids and vasopressors if necessary. Seek emergency medical attention.

Storage and Handling

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

Stability: Stable for 24 months when stored properly.