ClassIndications
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
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