IC4 Migraine meds pharmacology Flashcards
(29 cards)
What causes a headache/migraine? (pathophysiology)
vasodilation of intracranial extracerebral (ie. meningeal) bood vessels –> activation of perivascular trigeminal nerves –> releases vasoactive neuropeptides –> promotes neurogenic inflammation
What are the common OTC meds that can be used for headache/mild migraine?
paracetamol
NSAIDs
What are the medications available for moderate to severe migraines refractive to NSAIDs and paracetamol?
- cafergot
- sumatriptan
- erenumab
What are the components of cafergot?
caffeine + ergotamine
Describe the MOA of cafergot
Ergotamine: 5-HT1B/1D receptor agonist + alpha adrenergic receptor partial agonist
Caffeine: cranial vasoconstrictor + enhances GI absorption of ergotamine
When can cafergot be used?
Acute treatment of migraine
What quirk does cafergot have?
Inhibits 3A4
What is the impact of its quirk?
Avoid use with other 3A4 inhibitors eg. macrolide abx as it increases risk of ergot toxicity
What are the common side effects of cafergot?
N/V
What are the rare side effects of cafergot?
- Hypersensitivity
- MI
- Ergot poisoning
What drugs cannot be used together with cafergot?
other vasoconstricting agents eg. ergot alkaloids, sumatriptan, other 5HT1 agonists
Describe the MOA of sumatriptan
Selective agonist for 5-HT1B and 5-HT1D receptors on trigeminal nerves and intracranial extracerebral (ie. meningeal) blood vessels
*does not affect cerebral blood flow
When can sumatriptan be used?
Acute treatment of migrane w or w/o aura and those a/w menstrual period in women
What are the common side effects of sumatriptan?
- Dysgeusia (unpleasant taste)
- N/V
- Dizziness
- Flushing, tingling sensation
What are the rare and serious side effects of sumatriptan?
- Serotonin syndrome (feeling agitated & restless, other mental changes eg. hallucination, heavy sweating/shivering, fast HR/irregular heartbeat, rigit/twitching muscles, N/V or diarrhoea)
- MI
What are the contraindications of sumatriptan?
- hypersensitivity to triptans
- concurrent MAOi
- MI
- uncontrolled HTN, IHD, PVD, CVA, TIA, severe hepatic impairment
How is sumatriptan cleared?
mainly via hepatic metabolism via MAO-A
Can sumatriptan be used in pediatrics?
no
Can sumatriptan be used in elderly >65?
use with caution
Can sumatriptan be used in pregnancy?
use w caution
Can sumatriptan be used in breastfeeding
excreted into breastmilk; withhold breastfeeding for 8-12h after dose
Can sumatriptan be used in renal impairment?
yes; no dosage adj req
Can sumatriptan be used in hepatic impairment?
mild-moderate: dose reduction (due to increased F)
severe: C/I
What are the key DDIs to look out for sumatriptan?
- ergotamines (avoid sumatriptan within 24h of ergot meds; avoid ergot meds within 6h after taking sumatriptan)
- MAOi (cannot use triptan within 2wk of discontinuation of MAOi)
- triptans (cannot take another triptan within 24h after taking sumatriptan)
