naratriptan hydrochloride


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naratriptan hydrochloride

Amerge, Naramig (UK)

Pharmacologic class: Selective 5-hydroxytryptamine1 (5-HT1) agonist

Therapeutic class: Vascular headache suppressant, antimigraine drug

Pregnancy risk category C

Action

Binds with specific 5-HT1 receptors in intracranial blood vessels and sensory trigeminal nerves, leading to vasoconstriction and migraine relief

Availability

Tablets: 1 mg, 2.5 mg

Indications and dosages

Migraine headache

Adults: 1 or 2.5 mg P.O. as single dose; may repeat in 4 hours. Don't exceed 5 mg in 24 hours; don't use to treat more than four headaches per month.

Dosage adjustment

• Mild to moderate renal or hepatic impairment

Contraindications

• Hypersensitivity to drug or its components

• Hemiplegic or basilar headaches

• Severe renal, cardiovascular or hepatic impairment

• History of cerebrovascular or peripheral vascular conditions

• Ischemic bowel disease

• Uncontrolled hypertension

• Use of ergot-type drugs (such as dihydroergotamine) and other 5-HT1 agonists within 24 hours

• MAO inhibitor use within past 14 days

Precautions

Use cautiously in:

• mild to moderate renal or hepatic impairment, cardiovascular risk factors

• elderly patients (not recommended)

• pregnant or breastfeeding patients

• children (safety not established).

Administration

• Know that drug does not prevent migraine.

• Give only if patient's cardiovascular status has been evaluated and determined to be safe, and if first dose can be given under supervision.

Adverse reactions

CNS: dizziness, drowsiness, malaise, fatigue, paresthesia, cerebral hemorrhage, subarachnoid hemorrhage, stroke, other cerebrovascular events

CV: significant blood pressure elevation including hypertensive crisis (rare), coronary artery vasospasm, myocardial infarction, ventricular fibrillation or tachycardia

GI: nausea, vomiting, colonic ischemia with abdominal pain, bloody diarrhea

Other: pain or pressure sensation in throat or neck, peripheral vascular ischemia, serotonin syndrome, hypersensitivity including anaphylaxis or anaphylactoid reactions

Interactions

Drug-drug. Ergot-type compounds (dihydroergotamine, methysergide): prolonged vasospastic reaction

Hormonal contraceptives: increased naratriptan blood level and effects

MAO inhibitors: increased systemic exposure to naratriptan, increased risk of adverse reactions

Selective serotonin reuptake inhibitors: weakness, hyperreflexia, incoordination Sibutramine: serotonin syndrome

Drug-herbs. S-adenosylmethionine (SAM-e), St. John's wort: increased risk of adverse serotonergic effects

Drug-behaviors. Cigarette smoking: increased naratriptan metabolism

Patient monitoring

• Maintain especially close monitoring in patients with cardiovascular risk factors (such as hypertension, hypercholesterolemia, obesity, diabetes mellitus, cigarette smoking, strong family history), postmenopausal women, and men older than age 40.

• Assess vital signs and ECG.

• Monitor neurologic status closely. Institute safety measures as needed to prevent injury.

Discontinue drug if serotonin syndrome is suspected.

Patient teaching

• Tell patient to take at first sign of headache.

• Advise patient to take second dose (if approved) at least 4 hours after first dose if headache has not gone away completely or has returned.

• Caution patient not to take more than two tablets in a 24-hour period.

Instruct patient how to recognize and immediately report signs and symptoms of stroke and other neurologic conditions, serotonin syndrome, hypersensitivity, or bloody diarrhea.

• Advise patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.

• Tell patient to avoid cigarette smoking and to discuss herb use with prescriber.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, herbs, and behaviors mentioned above.