Monoamine oxidase with triptans

The triptans should be used with caution in patients on lithium, monoamine oxidase inhibitors or selective serotonin reuptake inhibitors, due to the rare occurrence of the serotonin syndrome. 

Drugs used in the treatment of acute migraine, such as sumatriptan and rizatriptan, are 5-HTiB/iD-receptor agonists and could theoretically interact pharmacodynami-cally with SSRIs to cause serotonin toxicity. Triptans are metabolized mainly by monoamine oxidase, which makes pharmacokinetic interactions with SSRIs unlikely. Although case series have suggested that sumatriptan can be safely combined with SSRIs (SEDA-22, 14), there are occasional reports of toxicity. 

Some of the triptans are metabolized by monoamine oxidase and they should not be used with monoamine oxidase inhibitors. This includes almotriptan (34), rizatriptan (35), sumatriptan (36), and zolmitriptan (28). The effect of moclobemide on the pharmacokinetics of almotriptan was less than with other triptans (34). 

The triptans are contraindicated in patients who have a history of ischemic or vasospastic CAD, cerebrovascular or peripheral vascular disease, or other significant cardiovascular diseases. Because triptans may cause an acute, usually small, increase in blood pressure (BP), they also are contraindicated in patients with uncontrolled hypertension. Naratriptan is contraindicated in patients with severe renal or hepatic impairment. Rizatriptan should be used with caution in patients with renal or hepatic disease but is not contraindicated in such patients. Sumatriptan, rizatriptan, and zolmitriptan are contraindicated in patients who are taking monoamine oxidase inhibitors. 

CYP1A2 and may therefore be expeeted to have additional interaetions. The picture with zolmitriptan beeomes more eomplieated sinee it is also metabolised by monoamine oxidase A. Naratriptan appears unlikely to undergo significant pharmacokinetic interactions since half the dose is excreted unchanged and the rest metabolised by a variety of isoenzymes. A summary of the metabolic pathways of the triptans can be found in Table 16.2 , (below). 

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