Article: Sumatriptan

Sumatriptan
Systematic (IUPAC) name
1-[3-(2-dimethylaminoethyl)-1H-indol-5-yl]- N-methyl-methanesulfonamide
Identifiers
CAS number	103628-46-2
ATC code	N02CC01
PubChem	5358
DrugBank	APRD00379
Chemical data
Formula	C14H21N3O2S
Mol. weight	295.402 g/mol
Pharmacokinetic data
Bioavailability	15% (oral)/ 96 % (s.c)
Protein binding	14%-21%
Metabolism	MAO
Half life	2.5 hours
Excretion	60% urine; 40% feces
Therapeutic considerations
Pregnancy cat.	C
Legal status
Routes	tablet, subcutaneous injection, nasal spray

Sumatriptan (Imitrex, Imigran,Imigran Recovery ) is a triptan drug including a sulfonamide group which was originally developed by Glaxo for the treatment of migraine headaches.

Approval and availability

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. In the United Kingdom, sumatriptan is available over the counter, under the name of Imigran Recovery. It is sold in packs of two 50mg tablets for approximately £7.99. Larger pack sizes, the nasal spray, and the liquid preparation for injection are still only available by prescription.

Mode of action

Often times, seratonin levels in the brain become extremely erratic before the onset of a migraine. In an attempt to stabalize this, sumatriptan is administered to help aid in leveling the seratonin levels in the brain. Sumatriptan is structurally similar to seratonin, and is a 5-HT (5-HT_1D) agonist, which is the same receptor that seratonin binds to. 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.

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.