Triptans, belonging to a family of tryptamine-based drug, are selective serotonin receptor (5-HT) agonists used in the treatment of acute migraine attacks andcluster headaches. Basis for the discovery of triptans was laid in 1960s by observations that vasoconstriction produced by 5-HT, ergotamine, and noradrenaline reduced migraine attacks. Platelet 5-HT levels were found to be reduced during migraine. As 5-HT itself could not be researched, efforts were focused on the receptors of 5-HT in order to discover and develop a more specific agonist for 5-HT receptors. This led to discovery of several types and subtypes of 5-HT. Several compounds were tested and discarded because of low bioavailability. Continued research led to the discovery of the first triptan drug,sumatriptan, that had both vasoconstriction effect as well as better oral bioavailability. Sumatriptan was first launched in Europe in 1991 and became available 1993 in the United States. Several other triptans have been developed since then. Marketed triptans for migraine are:
Sumatriptan/naproxen, combination of a triptan with a long-acting nonsteroidal antiinflammatory drug, is approved for acute treatment and sustained relief of migraine.
Pharmacodynamics.5-HTreceptors are all G-protein coupled receptors except for 5-HT3, which is a ligand-gated ion channel. The receptors that have been found to be involved in migraine are 5-HT1B, 5-HT1D, and 5-HT1F receptors. 5-HT1B receptors are found in meningeal arteries. The 5-HT1D receptors are located primarily in the trigeminal nerve in the central nervous system; they are also found in vascular smooth muscles. The amino acids contributing to the binding of ligands to the receptor are aspartic acid, phenylalanine, serine, threonine, tryptophan, and tyrosine.
Effect on migraine. Triptans are specific and selective agonists for the 5-HT1 receptors. There is an increase in the rate of brain serotonin (5-HT) synthesis during migraine attacks, and triptans exert a negative feedback regulation of brain serotonin synthesis along with modulation of pain pathways(Sakai et al 2008).Sumatriptanbinds to 5-HT1D receptors; zolmitriptan, rizatriptan, naratriptan, almotriptan, and frovatriptan binds to 5-HT1B/1D; and eletriptan binds to 5-HT1B/1D/1F receptors. Triptans have no significant activity at 5-HT2 or 5-HT3 receptors or at dopamine, gamma-aminobutyric acid, or adrenoreceptors. The beneficial effect of triptans in patients with migraine is related to their multiple mechanisms of action at sites implicated in the pathophysiology of migraine. These mechanisms include:
• Vasoconstriction of painfully dilated cerebral vessels without affecting cerebral circulation.
• Inhibition of nociceptive neurotransmission.
• Inhibition of the release of vasoactive peptides by trigeminal nerves.
• Sumatriptan has direct scavenging activity on free radicals and nitric oxide, but it inhibits the nitric oxide response by inhibiting trigeminal activation andCGRPrelease.
• Neither peripheral nor central trigeminovascular neurons are directly inhibited by triptans, but the action appears to be exerted through presynaptic 5HT1 receptors in the dorsal horn to block synaptic transmission between axon terminals of the peripheral trigeminovascular neurons and cell bodies of their central counterparts.
Effect on non-migrainous pain. 5-HT receptors are not localized to afferents in the head but are found throughout the body, suggesting that the triptans should be able to modulate non-migrainous pain; triptans have been shown effective in various non-cranial, non-migrainous pain states. Triptans have no effect on acute pain, but they profoundly reverse experimental hypersensitivity in behavioral models of inflammatory pain in mice. The ability of the triptans to regulate inflammatory pain is affected by the expression and localization of the 5-HT receptor, which is upregulated in persistent injury and pain. Thus, these results suggest that triptans can provide treatment of prolonged orchronic pain. Advantages of using triptans as analgesics are:
• Triptans are non-addictive and less susceptible to substance abuse, unlike other analgesics such as morphine.
• Triptans may potentiate the analgesic effects when used in combination with other analgesics.
• Such combination therapy may allow lower doses of drugs to be effective, reduce tolerance in long-term efficacy, and increase the therapeutic index.
Pharmacokinetics.The pharmacokinetics of oral triptans is shown in Table 1.
Table 1. Pharmacokinetics of Oral Triptans
Renal clearance (mL/min-1)
After absorption, triptans are extensively metabolized to an inactive indoleacetic acid analog that is excreted mainly in the urine. Pharmacokinetics varies according to the method of delivery. A linear relationship is observed between total applied current and sumatriptan delivery to reach therapeutic blood levels following transdermal delivery by an iontophoresis patch, which uses an electrical current to propel sumatriptan across intact skin into underlying tissue.
Relatively shorttmaxand good bioavailability are associated with rapid onset of action. Ability to cross theblood-brain barrierand relatively long terminal elimination half-life may result in a lower incidence of headache recurrence. Sumatriptan and rizatriptan undergo first-pass hepatic metabolism and result in lower bioavailability.
Formulations and methods of delivery of triptans.The delivery system of triptans plays an important role in the onset of action. Subcutaneous injection is the fastest way to control rapidly progressing migraine attacks. The sumatriptan nasal spray provides faster onset of action than the tablets, but it is not suitable for all patients because of bad taste and lack of consistency of response.
The drawbacks of triptans for the treatment of migraine are: (1) low oral bioavailability and (2) low concentration of active metabolites. Improved formulations and methods of delivery would be beneficial. Currently available routes of administration of triptans include subcutaneous (sumatriptan), nasal spray (sumatriptan and zolmitriptan), rectal (sumatriptan), rapidly-dissolving wafer (rizatriptan and zolmitriptan), and oral tablets (all).
In comparative clinical trials, oral triptans outperform oral ergotamine mostly because of the extremely low oral bioavailability of ergotamine; compared with NSAIDs, triptans are not, in most cases, superior to aspirin(Tfelt-Hansen 2009).
Triptans are indicated for the treatment of migraine headaches.
Off-label and investigational uses.Triptans are under investigation for migraine variants, and special methods of administration are also being studied. Triptans seem to be safe and effective treatment for mosthemiplegic migrainepatients(Artto et al 2007). Investigational uses include those for non-migraine headaches and other conditions:
• Patients receiving ergot compounds. Triptans should not be given intravenously within 24 hours of administration of an ergot compound.
• Patients who have demonstrated hypersensitivity to any triptan.
Goals and duration of treatment
Clinical studies show that most patients who fail to obtain adequate alleviation of symptoms with one triptan may be successfully treated with a different triptan. The 7 available triptans show more similarities than differences in action. Almotriptan 12.5 mg is as effective assumatriptan100 mg and zolmitriptan 2.5 mg(Chen and Ashcroft 2007). None of the available triptans produce an effective response in every migraine attack, and prolonged use of triptans may produce an increase in the migraine frequency and headache. A survey has shown that compliance with triptan therapy included satisfaction and confidence in triptans’ ability to stop the migraine and associated symptoms(Cady et al 2009).
The ideal triptan for migraine.Some of the disadvantages of triptans have been overcome with the introduction of newer triptans such as zolmitriptan and naratriptan, but the search for new agents continues. The desirable properties sought for a drug for acute migraine are:
• It should be more efficacious than currently available drugs.
• It should be tolerated better.
• The recurrence rate should be low.
• It should have a prophylactic role as well.
• It should provide improved patient choice.
Individualization of use of triptans for migraine.With a large number of triptans now available, it may be possible to match individual patient needs with the specific characteristics of the individual triptans to optimize therapeutic benefit. Pharmacogenetics provides the possibility of tailoring the therapeutic approach to individual patients in order to maximize treatment efficacy while minimizing the potential for unwanted side-effects(Buzzi 2008). Pain relief by triptans is significantly modulated by a common genetic variant–G protein beta3(Schurks et al 2007). Genetic profiling of predisposition to migraine should facilitate the development of more effective diagnostic and therapeutic applications. The development of the International Hap Map project could provide a powerful tool for identification of the candidate genes in this complex disease, and pharmacogenomics research could be the promise for individualized treatments and prevention of adverse drug response(Piane et al 2007). Pharmacogenomics will most likely provide a stronger scientific basis for optimizing triptan therapy on the basis of each patient’s genetic constitution(Tfelt-Hansen and Brosen 2008).
Doses, formulations, and duration of action of triptans are shown in Table 3.
Table 3. Doses, Formulations, and Duration of Action of Triptans
Maximum daily dose (mg)
Onset of action (min)
Duration of action
25, 50, 100
Precautions and use in special groups
Pediatric.Safety in children has not been established.
Geriatric.No information is known about the safety in patients over the age of 65 years because they were excluded from clinical trials.
Pregnancy.Triptans fall into category C of the United States Food and Drug Administration regarding safety of use during pregnancy. Animal reproduction studies have shown an adverse effect on the fetus, and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks. Although pregnancy registries are maintained by the manufacturer, triptan use in pregnancy has not been extensively studied. There are no data to suggest teratogenicity for any of the triptans although preterm birth rates appear to be elevated(Soldin et al 2008). Caution should be exercised in recommending the use of triptans during pregnancy.
Triptans are secreted in human milk, and caution should be exercised when administering any of the triptans to nursing mothers.
Anesthesia.No special precautions are required for patients on triptans.
Triptans are compatible with most of the commonly used drugs, including those used for the treatment of headaches. Concomitant use of triptans andSSRIsor selective serotonin/norepinephrine reuptake inhibitors can lead toserotonin syndrome. An alert was issued by the United States Food and Drug Administration in 2006 for this interaction based on reports of 27 cases in a 5-year period, which have not been validated or have not met the criteria of serotonin syndrome diagnosis. In view of the small number of case reports among a large number of patients who take this drug combination, one publication states that this combination can be used where clinically appropriate and that physicians should familiarize themselves with detection of serotonin syndrome(Wenzel et al 2008). Interactions may also occur with the following categories of drugs:
• Ergot-containing compounds
• Monoamine oxidase inhibitors
• Calcium channel-blocking antagonists
• Beta blockers
Triptans are generally well tolerated with minor adverse effects. Those reported include the following: