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Migraine Pregnancy: Avoid — insufficient data; animal studies show reproductive toxicity; use triptan or paracetamol alternatives in pregnancy

Lasmiditan

Brand names: Reyvow

Adult dose

Dose: 50–200 mg orally as a single dose at onset of migraine
Route: Oral
Frequency: Single dose; may repeat after 2 hours if inadequate response
Max: 200 mg per day (max 2 doses; second dose only if first partially effective)
Take as soon as migraine starts. Do NOT drive or operate machinery for at least 8 hours after taking — CNS depression persists. Available as 50 mg and 100 mg tablets.

Paediatric dose

Dose: Seek specialist opinion N/A/kg
Route: Oral
Frequency: N/A
Max: N/A
Not established in paediatrics; seek specialist paediatric neurology opinion

Dose adjustments

Renal

No dose adjustment required

Hepatic

No dose adjustment in mild-moderate impairment; avoid in severe hepatic impairment

Paediatric weight-based calculator

Not established in paediatrics; seek specialist paediatric neurology opinion

Clinical pearls

  • Mechanism: first-in-class selective 5-HT1F receptor agonist (ditan class) — 5-HT1F receptors expressed on trigeminal nerve terminals; lasmiditan inhibits calcitonin gene-related peptide (CGRP) release and trigeminovascular signalling; critically, 5-HT1F receptors are NOT expressed in coronary vessels — lasmiditan has NO vasoconstrictive effect
  • KEY ADVANTAGE over triptans: no vasoconstrictive activity — safe in patients with established cardiovascular disease, ischaemic heart disease, stroke history, or uncontrolled hypertension where triptans are contraindicated
  • SAMURAI trial (NEJM 2019): lasmiditan 200 mg vs placebo — 32% achieved pain freedom at 2 hours vs 15% placebo; SPARTAN trial confirmed dose-response across 50 mg, 100 mg, and 200 mg
  • MHRA: licensed for acute treatment of migraine (with or without aura) in adults; not for migraine prevention; NICE assessment ongoing in UK
  • DRIVING WARNING MANDATORY: lasmiditan causes CNS impairment lasting up to 8 hours — patients MUST NOT drive or operate machinery; this is a MHRA black box equivalent warning; schedule dose at time of sleep
  • No serotonin syndrome data vs triptans: combination with SSRIs/SNRIs not specifically studied; serotonin syndrome theoretical concern but 5-HT1F binding not associated with the serotonergic side effect profile of 5-HT1B/1D activation

Contraindications

  • Known hypersensitivity to lasmiditan
  • Driving within 8 hours of taking — ABSOLUTE (CNS depression)

Side effects

  • Dizziness (most common — dose-dependent; 11–15%)
  • Paraesthesias
  • Sedation and fatigue
  • Nausea
  • CNS effects: cognitive slowing, diplopia (dose-dependent)
  • DYSSOMNIA (sleep disturbance)

Interactions

  • CNS depressants (alcohol, benzodiazepines, opioids) — additive CNS depression; AVOID alcohol for 8 hours
  • P-glycoprotein substrates (lasmiditan inhibits P-gp — may increase digoxin exposure; monitor digoxin levels)
  • Serotonergic drugs (theoretical risk — lasmiditan is a 5-HT1F agonist; limited interaction data)

Monitoring

  • Headache diary (frequency, time to pain freedom, adverse effects)
  • CNS side effects (dizziness, sedation — dose-related)
  • Use frequency (medication overuse headache risk with frequent use — as per triptans)

Reference: BNFc; BNF 90; SAMURAI trial NEJM 2019;381(23):2230-2241; SPARTAN trial NEJM 2019;381(23):2245-2256; MHRA SPC; EAN Migraine Guidelines 2022. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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