Sumatriptan

Class

Indications

Administration/Absorption

Dosage

Distribution

  • Volume of distribution 2.7 L/kg [subcutaneous dosing]

Mechanism

  • Selective agonist of vascular serotonin ((5-hydroxytryptamine; 5-HT) type 1-like receptors, likely the 5-HT1D and 5-HT1B subtypes

    • The 5-HT1B and 5-HT1D receptors function as autoreceptors

    • Adenylate cyclase activity is inhibited via regulatory G proteins; increases intracellular calcium, and affects other intracellular events

    • Inhibits the firing of serotonin neurons and cause a reduction in the synthesis and release of serotonin upon activation

  • Has no significant affinity or pharmacological activity at:

    • 5-HT2, 5-HT3 receptor subtypes

    • Alpha1-, alpha2-, or beta-adrenergic receptors

    • Dopamine1 or 2 receptors

    • Muscarinic receptors

    • Benzodiazepine receptors

  • This results in vasoconstriction and inhibtion of sensory nociceptive (trigeminal) nerve firing and vasoactive neuropeptide release.

Excretion

  • Hepatic metabolism

    • In vitro studies with human microsomes suggest that sumatriptan is metabolized by monoamine oxidase (MAO), predominantly the A isoenzyme.

  • Only 3% of the dose is excreted in the urine as unchanged sumatriptan

    • 42% of the dose is excreted as the major metabolite, the indole acetic acid analogue of sumatriptan

  • Half-life 2.5 hrs

Side effects

  • Symptoms of overdose include convulsions, tremor, paralysis, inactivity, ptosis, erythema of the extremities, abnormal respiration, cyanosis, ataxia, mydriasis, salivation, and lacrimation

Interactions

Contraindications