triptans

introduction

triptans are a group of tryptamine-based drugs used to Rx acute migraines
they were introduced in the 1990's and have variable efficacy on aborting a migraine attack, and do not prevent it recurring.
they are not addictive and generally are effective within 30-90 minutes of responders.
poor responders should consider taking a dose within 20min of onset or trying a different triptan.
not for use in pregnancy

act on serotonin 5-HT_1B and 5-HT_1D receptors in cranial blood vessels causing their vasoconstriction, and in nerve endings, and inhibition of pro-inflammatory neuropeptide release (eg. CGRP, substance P).

severe hepatic impairment
uncontrolled hypertension;
CAD; IHD; Prinzmetal's angina; peripheral vascular disease;
CVA, TIA history;
ergotamine incl derivatives (+/- 24 hrs);
concomitant 5HT1 receptor agonists;
potent CYP3A4 inhibitors (ketoconazole, itraconazole, erythromycin, clarithromycin, amprenavir, ritonavir, indinavir, saquinavir, nelfinavir, nefazodone (within 48 hrs))

not for use in hemiplegic, ophthalmoplegic, basilar migraine, headache assoc with stroke, aneurysm rupture, other serious conditions;
excessive use;
CV disease (or risk); heart failure; myocardial ischaemia risk;
renal impairment;
elderly > 65 yrs; pregnancy, lactation, children < 17 yrs

recurrence of migraine later that day
a range of common but usually not clinically important adverse effects
serotonin syndrome if concurrent use of other serotonergic agents or in overdose
large does of sumatriptan (> 200mg/d) may cause sulfhaemoglobinaemia
theoretically risk of:
- coronary artery spasm but life-threatening cardiac events are rare, nevertheless, it should not be used in those with ischaemic heart disease
- exacerbation of a migraine-induced neurologic event associated with intracranial vasoconstriction and CNS ischaemia

Imigran
usual oral dose is 50-100mg
usual s/c dose is 6mg
sumatriptan was the first triptan available and was introduced in the US in 1991
Zelrix was introduced in 2008 in the US as a computer chip controlled iontophoretic transdermal patch which can deliver a single dose through the skin within 30min.
see also wikipedia