Generic Name

Dihydroergotamine

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Classification

FDA Approved Indications

• Migraine with or without aura
• Cluster headaches

Mechanism of Action

Dihydroergotamine is a potent vasoconstrictor that acts on alpha-adrenergic and serotonin receptor sites, leading to vasoconstriction of cranial blood vessels and reduction of neurogenic inflammation involved in migraines.

Dosage and Administration

Adult: The typical dose is 1 mg administered intravenously, intramuscularly, or subcutaneously at the onset of migraine. Repeat every hour as needed, up to 2 mg in 24 hours.

Pediatric: Use is generally not recommended in children due to limited data.

Geriatric: Use with caution; start at lower doses due to increased risk of vasoconstriction and blood flow issues.

Renal Impairment: Adjust dosage and monitor closely, as renal impairment can prolong drug effects.

Hepatic Impairment: Use with caution; hepatic metabolism may be impaired, increasing drug levels.

Pharmacokinetics

Absorption: Poor oral absorption; administered parenterally or intranasally.

Distribution: Widely distributed; crosses the blood-brain barrier.

Metabolism: Primarily hepatic via CYP3A4 enzyme system.

Excretion: Metabolites excreted in bile and urine.

Half Life: Approximately 2 hours.

Contraindications

• History of coronary artery disease, peripheral vascular disease, hypertension, or liver disease.
• Pregnancy (category X), lactation.

Precautions

• Use with caution in patients with risk factors for vasospasm, ischemic heart disease, or cerebrovascular disease. Monitor blood pressure and circulatory status during therapy.

Adverse Reactions - Common

• Nausea, vomiting (Common)
• Vasoconstriction leading to cold extremities, hypertension (Common)

Adverse Reactions - Serious

• Ischemic events (e.g., myocardial infarction, stroke) (Serious (rare but severe))
• Vasospasm leading to gangrene (Rare)

Drug-Drug Interactions

• Inhibitors of CYP3A4 (e.g., macrolide antibiotics, azole antifungals, protease inhibitors) due to increased risk of ergotism.

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Do not use in pregnancy or breastfeeding.
• Report any signs of cold extremities, pain, numbness, or unusual skin color changes.
• Avoid concurrent use of other vasoconstrictive agents.

Special Considerations

Black Box Warnings:

• Risks of vasoconstriction may lead to ischemia and gangrene.
• Use caution with CYP3A4 inhibitors.

Genetic Factors: Genetic variations in CYP3A4 may affect metabolism.

Lab Test Interference: May affect blood pressure monitoring and vascular assessments.

Overdose Management

Signs/Symptoms: Severe vasoconstriction, ischemia, hypertension.

Treatment: Discontinue drug, provide supportive care, administer vasodilators if indicated, and implement measures to improve circulation.

Storage and Handling

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

Stability: Stable for the duration of labeled expiration date.