Eletriptan

Eletriptan is a triptan used for acute treatment of migraine, with strong efficacy but significant interactions because it is a cytochrome P450 3A4 substrate. It is contraindicated with boosted protease inhibitor antiretroviral regimens and several macrolide and azole antimicrobials.

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

Pharmacokinetics. Bioavailability about 50% and half-life about 4 hours. It is cleared by cytochrome P450 3A4. Food increases absorption, especially fatty meals.

First-line use. Acute migraine attacks with or without aura.

• Oral eletriptan: 40 mg at onset (20 mg if 40 mg is not tolerated). If migraine returns, repeat after at least 2 hours, and give a second dose of up to 40 mg. Maximum 80 mg in 24 hours.

• If 40 mg is not effective for an attack, use 80 mg for the next attack if allowed by the label.

Kidney, liver, weight and age.

• Kidney: mild to moderate impairment, start 20 mg and limit to 40 mg in 24 hours. Severe impairment, contraindicated or avoided depending on the label.

• Liver: mild to moderate impairment, no adjustment. Severe impairment, avoid.

• 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, severe hepatic impairment, ergotamine or another triptan within 24 hours, and strong cytochrome P450 3A4 inhibitors (ketoconazole, itraconazole, clarithromycin, erythromycin, ritonavir, nelfinavir, nefazodone) within 72 hours.

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

Common adverse effects. Asthenia, dizziness, somnolence, nausea, dry mouth, and throat or chest tightness.

Interactions. Strong cytochrome P450 3A4 inhibitors are contraindicated, and moderate inhibitors (verapamil, diltiazem, fluconazole) need caution. Strong inducers (rifampicin, carbamazepine, phenytoin) lower levels. Ergot alkaloids and other triptans are contraindicated.

Common prescribing errors. Prescribing with boosted protease inhibitor regimens such as lopinavir with ritonavir or atazanavir with ritonavir. Giving a macrolide or azole without checking. Use on more than 10 days each month.

Special groups.

• Pregnancy: limited data; avoid unless clearly needed.

• Breastfeeding: use with caution; delay breastfeeding for 24 hours in some labels.

• Regional: antiretroviral regimens and rifampicin are common in East Africa, so review the medicines list before prescribing.

Formulations. Tablets 20 and 40 mg (and 80 mg in some markets). Swallow with water.

Monitoring.

• Baseline blood pressure and cardiovascular risk review, and a medicines review for cytochrome P450 3A4 inhibitors.

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

Stopping. No taper is needed.

Referral and escalation. Refer for poor response or frequent attacks needing prevention.