New migraine-specific medications, the triptans, are changing the clinician’s approach to the treatment of migraine. These drugs are pharmacologically based on agonism of serotonin (5-hydroxytryptamine; 5-HT) receptors.
The triptans are selective 5-HT1B/1D receptor agonists and are believed to reverse the mechanisms of migraine, which may include changes in durai vessel calibre, neurogenic inflammation and central trigeminal neuronal activation.
The first marketed triptan was sumatriptan. Sumatriptan is available in a highly effective and rapidly active subcutaneous injectable formulation (optimal dose 6mg), as well as nasal (optimal dose 20mg), oral (optimal dose 50mg) and suppository (optimal dose 25mg) forms. The multiple forms allow for maximal flexibility in crafting an acute care regimen for patients.
New triptans are being released in rapid sequence; each new drug has some distinct clinical advantages. All of the triptans released after sumatriptan are more lipophilic and have higher oral bioavailability than sumatriptan. Zolmitriptan was the second marketed triptan, and is available in oral tablet form (optimal dose 2.5mg). A fast melt preparation is to be released in Europe in 1999 and a nasal spray form is under development. Zolmitriptan is a well absorbed oral triptan with very high consistency of effect in nonblind studies of over 1 year in duration.
Naratriptan (optimal dose 2.5mg) has a relatively slow onset of action but is associated with the lowest headache recurrence rate of the currently available triptans. It has a very good adverse event profile with excellent tolerability.
Rizatriptan is available as an oral tablet and a rapidly dissolving oral wafer (melt formulation). The optimal dose is 10mg. It is similar to sumatriptan in being an effective oral triptan with a relatively high recurrence rate.
Future triptans include eletriptan, which has a very high efficacy in oral form at a dose of 80mg, but a high rate of adverse events at this dose. Lower doses (20 and 40mg) are similar in profile to sumatriptan. Frovatriptan (optimal dose 2.5mg) has an onset of effect and overall efficacy similar to those of naratriptan, but a very low recurrence rate. Almotriptan has the highest oral bioavailability of the triptans.
Selection of an acute care migraine medication should be based on need for specific delivery form, headache- and pain-free response at 2 and 4 hours after administration, adverse event profile, consistency of response and recurrence rate.
Adverse events for triptans include tightening, flushing and paraesthesias of unknown cause. All triptans cause narrowing of arteries, including coronary arteries, and although serious adverse vascular events are very rare, triptan use is contraindicated in patients with vascular disease.