Strong vasodilators cause vasodilation and oedema, which activate pain nerve endings. This pain can be described as one’s head feeling as though it is about to explode.
5-HT or serotonin receptors, agonists constrict the arteries which then inhibits trigeminal nerve transmission and vasoactive peptide release.
Ergotamine is a partial 5-HT1 agonist which causes vasoconstriction in the intracranial arteries and inhibits trigeminal nerve transmission.
Side effects include nausea, vomiting, diarrhoea, hallucinations, gangrene strong vasoconstriction, tachycardia and rebound headache. Contra-indications include cardiovascular disease, hypertension, patients suffering from liver and kidney impairment, pregnancy, and psychosis.
Sumatriptan, Zolmitriptan, Almotriptan, Eletriptan, Naratriptan- These drugs are 5-HT1B/1D/1F agonists. They constrict the large arteries, inhibits trigeminal nerve transmission and vasoactive peptide release.
Metoclopramide-Anti-emetic, D2 antagonist at the chemoreceptor trigger zone in CNS
Cyclizine-Anti-emetic, First-generation ant-histamine, competitive antagonist at H1, muscarinic, alpha and 5-Ht receptors.
Beta-blockers and alpha 2 agonists can be used as migraine prophylaxis. Propranolol(B-blocker) helps to stop a migraine but should not be taken during a migraine. Clonidine (alpha-2 agonist) causes vasodilation before initial vasoconstriction, but caution should be taken as it could induce a migraine attack. Calcium channel blocker-drugs could also be used such as Verapamil, Flunarizine (could prevent often attacks of migraines, Blocks H1) and Diltiazem. These drugs cause vasodilation after initial vasoconstriction. Side effects when taking Flunarizine include weight gain, depression, and fatigue.