Sumatriptan

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Sumatriptan (Imitrex®, Imigran®) is a triptan drug originally developed by Glaxo for the treatment of migraine headaches. Several dosage forms for sumatriptan have been approved, including tablets, solution for injection, and nasal inhalers. Sumatriptan was the first triptan available (in 1991), and, in the United States and most developed countries, is available only by medical prescription.

Image:Sumatriptan.png sumatriptan
4-methylaminosulfonyl-N,N-dimethyltryptamine
Chemical formula	C₁₄H₂₁N₃O₂S
Molecular weight	295.40
Bioavailability	15% (oral)/ 96 % (s.c)
Metabolism	MAO
Elimination half life	2.5 hours
Excretion	60% urine 40% feces
Pregnancy category	C
Delivery	tablet, subcutaneous injection, nasal spray
Indicated for: migraine headache cluster headache
Contraindications: coronary artery disease monoamine oxidase inhibitors
Side effects: Severe: coronary artery vasospasm transient myocardial ischemia myocardial infarction ventricular tachycardia ventricular fibrillation hypertensive crisis Atypical sensations: paresthesia Cardiovascular: palpitations syncope hypertension hypotension Ear, nose, and throat: tinnitus sensitivity to noise sinusitis allergic rhinitis upper respiratory inflammation Gastrointestinal: diarrhea Muscular: myalgia Neurological: phonophobia photophobia Respiratory: dyspnea Skin: sweating Miscellaneous: hypersensitivity

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Mode of action

Sumatriptan is a 5-HT (5-HT_1D) agonist. The specific receptor subtype it activates is present in the cranial and basilar arteries. Activation of these receptors causes vasoconstriction of those dilated arteries. Sumatriptan is also shown to decrease the activity of the trigeminal nerve.

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Pharmacokinetics

Sumatriptan is administered in several forms; tablets, subcutaneous injection, and nasal spray. Oral administration (as succinate) suffers from poor bioavailability, partly due to presystemic metabolism — some of it gets broken down in the stomach and bloodstream before it reaches the target arteries. A new rapid-release tablet formulation has the same bioavailability, but the maximum concentration is achieved on average 10-15 minutes earlier. When injected, sumatriptan is faster acting (usually within a minute), but the effect lasts for a shorter time. Sumatriptan is metabolised primarily by monoamine oxidase A into an indole acetic acid analogue, part of which is further conjugated with glucuronic acid. These metabolites are excreted in the urine and bile.

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References

Carpay J, Schoenen J, Ahmad F. Efficacy and tolerability of sumatriptan tablets in fast-disintegrating, rapid-release formulation for the acute treatment of migraine. Clin Ther 2004;26(2):214-223