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What is Drug of choice in acute severe migraine is: and explain in detail?
MIGRAINE *Severe, throbbing, pulsating headache usually unilateral headache (few hours to a few days in duration) *Associated with nausea, vomiting, sensitivity to light and sound, flashes of light, loose motion and others *Types: -Classical with aura -Without aura (common) *Pathophysiology: -Pulsatile dilatation of temporal or ceain cranial vessels -Vascular theory: initial vasoconstriction or shunting of blood through carotid aerio-venous anastomosis causing cerebral ischaemia -Neurogenic theory: depression of coical electrical activity followed by depression *Migraine attack associated with (based on histological studies): *sterile neurogenic perivascular edema *inflammation (clinically effective antimigraine medication reduce perivascular inflammation) SUMATRIPTAN *Selective agonist of 5-HT1B/1D receptor *No interaction with other 5-HT receptors *No interaction with adrenergic, dopaminergic and cholinergic receptors, GABA MOA: *Blockade of 5-HT1D/1B mediated constriction of dilated extracerebral blood vessel *Constriction of aeriovenous shunt of carotid aery *Inhibition of release of 5-HT and inflammatory neuropeptides around the affected vessels - supression of neurogenic inflammation *Supression of impulse transmission in trigeminovascular system Kinetics: *Poorly absorbed from GIT, bioavailability - 10 - 15% only *Complete absorption after subcutaneous administration Metabolized by MAO-A and excreted in urine, t1/2 is 2-3 Hrs *Administration & Doses: -Onset of acute attack -Better tolerated than ergotamine -50 to 100 mg as initial dose and repeated after 24 Hrs if required -Should not be given is 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 Ref: KD tripathi 8th ed