Large doses of sumatriptan can cause sulfhemoglobinemia, a rare condition in which the blood changes from red to greenish-black, due to the integration of sulfur into the hemoglobin molecule. If sumatriptan is discontinued, the condition reverses within a few weeks.
The most common side-effects reported by at least 2% of patients in controlled trials of sumatriptan (25, 50, and 100 mg tablets) for migraine are atypical sensations (paresthesias and warm/cold sensations) reported by 4% in the placebo group and 5–6% in the sumatriptan groups, pain and other pressure sensations (including chest pain) reported by 4% in the placebo group and 6–8% in the sumatriptan groups, neurological events (vertigo) reported by less than 1% in the placebo group and less than 1% to 2% in the sumatriptan groups. Malaise/fatigue occurred in less than 1% of the placebo group and 2–3% of the sumatriptan groups. Sleep disturbance occurred in less than 1% in the placebo group to 2% in the sumatriptan group.
Mechanism of action
Sumatriptan is structurally similar to serotonin (5HT), and is a 5-HT (types 5-HT1D and 5-HT1B) agonist. The specific receptor subtypes it activates are present on the cranial arteries and veins. Acting as an agonist at these receptors, sumatriptan reduces the vascular inflammation associated with migraines.
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, which, it is presumed, accounts for sumatriptan's efficacy in treating cluster headaches. The injectable form of the drug has been shown to abort a cluster headache within fifteen minutes in 96% of cases.
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 10 minutes), 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. Only about 3% of the active drug may be recovered unchanged.
There is no simple, direct relationship between sumatriptan concentration (pharmacokinetics) per se in the blood and its anti-migraine effect (pharmacodynamics). This paradox has, to some extent, been resolved by comparing the rates of absorption of the various sumatriptan formulations, rather than the absolute amounts of drug that they deliver.
Sumatriptan was the first clinically available triptan (in 1991). In the United States, it is available only by medical prescription. However, it can be bought over the counter in the UK and Sweden in 50 mg dosage. Several dosage forms for sumatriptan have been approved, including tablets, solution for injection, and nasal inhalers.
On April 15, 2008, the US FDA approved Treximet, a combination of sumatriptan and naproxen, an NSAID. This combination has shown a benefit over either medicine used separately.
In July 2009, the US FDA approved a single-use jet injector formulation of sumatriptan. The device delivers a subcutaneous injection of 6 mg sumatriptan, without the use of a needle. Autoinjectors with needles have been previously available in Europe and North America for several years.
On November 6, 2008, Par Pharmaceutical announced that it would begin shipping generic versions of sumatriptan injection (sumatriptan succinate injection) 4 mg and 6 mg starter kits and 4 mg and 6 mg pre-filled syringe cartridges to the trade immediately. In addition, Par anticipates launching the 6 mg vials early in 2009.
Mylan Laboratories Inc., Ranbaxy, Sandoz, Dr. Reddy's Pharmaceuticals and other companies have received FDA approval for generic versions of Imitrex tablets in 25-, 50-, and 100-milligram doses since 2009. The drug is available in U.S. and European markets, since Glaxo's patent protections have expired in those jurisdictions. However, sales of a generic delivered via nasal spray are still restricted in the United States.
WO 0134561 This is based on the original procedure. The hydrazine is prepared using "one-pot" methodology.
Treatment of the appropriately functionalized hydrazine hydrochloride with 4-chlorobutanal dimethyl acetal in ethanol and aqueous HCl gives an intermediate hydrazone.
Disodium phosphate was added and the reaction mixture was refluxed. This reaction is known as the Grandberg variation of the Fischer indole synthesis and involves displacement of the chloro group with the ammonia released during the formation of the indole ring.
Reaction of the 1° amine with formaldehyde and sodium borohydride in the presence of a buffer completes the synthesis.
^Pete, B. L.; Bitter, I. N.; Szántay, Jr., C.; Schön, I. N.; Töke, L. S. (1998). "Synthesis of 5-Substituted Indole Derivatives, I. An Improved Method for the Synthesis of Sumatriptan". Heterocycles48 (6): 1139. doi:10.3987/COM-97-8087.edit
^Pete, B. L.; Bitter, I. N.; Harsányi, K. L. N.; Tõke, L. S. (2000). "Synthesis of 5-Substituted Indole Derivatives, Part II. Synthesis of Sumatriptan through the Japp-Klingemann Reaction". Heterocycles53 (3): 665. doi:10.3987/COM-99-8815.edit