Sumatriptan is a?

SUMATRIPTAN *Selective agonist of the 5-HT1B/1D receptor *No interaction with adrenergic, dopaminergic and cholinergic receptors, GABA MOA: *Blockade of 5-HT1D/1B mediated constriction of dilated extracerebral blood vessel *Constriction of the aeriovenous shunt of carotid aery *Inhibition of release of 5-HT and inflammatory neuropeptides around the affected vessels - suppression of neurogenic inflammation *Suppression of impulse transmission in the trigeminovascular system Kinetics: *Poorly absorbed from GIT, bioavailability - 10 - 15% only *Complete absorption after subcutaneous administration *Metabolized by MAO-A and excreted in the urine, t1/2 is 2-3 Hrs *Administration & Doses: -The onset of an acute attack of migraine -Better tolerated than ergotamine -50 to 100 mg as initial dose and repeated after 24 Hrs if required -Should not be given is the first dose fails -SC dose - 12 mg (1 ml) stat and repeated if required *Adverse effects: Dose-related - Tightness of chest, feeling of heat, paresthesia of limbs, dizziness, and weakness (sho lasting) - common with SC route -Risk of MI and seizure and death Contraindications: IHD, epilepsy, hypeension, pregnancy, hepatic and renal impairment