Naratriptan

Naratriptan is a triptan with slower onset and longer duration than other triptans, used for acute treatment of migraine. It causes fewer adverse effects and less recurrence, which suits people with prolonged attacks or menstrual-related migraine, at the cost of a slower response.

Mechanism. Serotonin 5-HT1B/1D receptor agonist that constricts cranial vessels and inhibits release of calcitonin gene-related peptide.

Pharmacokinetics. Bioavailability about 70% and half-life about 6 hours. Peak is reached in 2 to 3 hours. It is cleared partly by the kidney and partly by cytochrome P450 enzymes, with no monoamine oxidase involvement.

First-line and alternative use. Acute migraine attacks, especially slow-onset or recurrent attacks.

• Oral naratriptan: 2.5 mg at onset. If migraine returns, repeat after at least 4 hours. Maximum 5 mg in 24 hours.

• Short-term prevention of menstrual migraine (off-label, specialist): 1 mg twice daily for 5 days, starting 2 days before expected menses.

Kidney, liver, weight and age.

• Kidney: mild to moderate impairment, maximum 2.5 mg in 24 hours. Severe impairment (creatinine clearance under 15 mL/min), contraindicated.

• Liver: mild to moderate impairment, maximum 2.5 mg in 24 hours. Severe impairment, contraindicated.

• Older adults: avoid over age 65 unless cardiovascular status is clear.

Contraindications. Ischaemic heart disease, previous myocardial infarction, coronary vasospasm, peripheral vascular disease, previous stroke or transient ischaemic attack, uncontrolled hypertension, hemiplegic or basilar migraine, severe renal or hepatic impairment, ergotamine or another triptan within 24 hours, and hypersensitivity.

Serious adverse effects. Myocardial infarction, coronary vasospasm, arrhythmia, stroke, serotonin syndrome, and medication overuse headache.

Common adverse effects. Nausea, dizziness, fatigue, tingling and throat or chest tightness, generally milder than with other triptans.

Interactions. Ergot alkaloids and other triptans are contraindicated. Selective serotonin reuptake inhibitors and St John's wort add serotonin syndrome risk. Naratriptan is a sulphonamide, so use caution with sulphonamide allergy.

Common prescribing errors. Repeating within 4 hours. Not reducing the dose in kidney or liver impairment. Use on more than 10 days each month.

Special groups.

• Pregnancy: limited data; avoid unless clearly needed.

• Breastfeeding: use with caution.

• Children: not licensed under 18 years in most regions.

Formulations. Tablets 1 and 2.5 mg. Swallow with water.

Monitoring.

• Baseline blood pressure, cardiovascular risk and kidney function.

• Headache diary, with acute treatment limited to under 10 days each month.

Stopping. No taper is needed.

Referral and escalation. Refer for poor response, frequent attacks, or suspected medication overuse headache.