Drug information of Rizatriptan

Rizatriptan

Drug group:

Rizatriptan is used to treat migraine headaches. Rizatriptan will only treat a headache that has already begun. It will not prevent headaches or reduce the number of attacks.

Mechanism of effect

Three distinct pharmacological actions have been implicated in the antimigraine effect of the triptans: (1) stimulation of presynaptic 5-HT1D receptors, which serves to inhibit both dural vasodilation and inflammation; (2) direct inhibition of trigeminal nuclei cell excitability via 5-HT1B/1D receptor agonism in the brainstem and (3) vasoconstriction of meningeal, dural, cerebral or pial vessels as a result of vascular 5-HT1B receptor agonism.

Pharmacodynamic

Rizatriptan is a selective agonist of serotonin (5-hydroxytryptamine; 5-HT) type 1B and 1D receptors.

Pharmacokinetics

Absorption:Rapid following oral administration. Bioavailability is 45%. Food has no effect on the bioavailability of rizatriptan. However, administering rizatriptan with food will delay by 1 hour the time to reach peak plasma concentration.Protein binding:14%. Rizatriptan is metabolized by monoamine
oxidase A isoenzyme (MAO-A) to an inactive indole acetic acid metabolite. Approximately 14% of an oral dose is excreted in urine as unchanged rizatriptan while 51% is excreted as indole acetic acid metabolite, indicating substantial first pass metabolism. Half life:2-3 hours

Dosage

Usual Adult Dose for Migraine
Use only after a clear diagnosis of migraine has been established Initial dose: 5 mg or 10 mg orally, once -Provided there has been a response to first dose,
a second dose may be administered at least 2 hours later if migraine returns. Maximum dose: 30 mg in a 24-hour period Usual Pediatric Dose for Migraine
Use only after a clear diagnosis of migraine has been established 6 years or older and weight less than 40 kg:
-Initial dose: 5 mg orally once 6 years or older and weight 40 kg or greater: -Initial dose: 10 mg orally once Maximum: 1 dose in any 24-hour period

Alerts

1-Cerebral hemorrhage, subarachnoid hemorrhage, and stroke have occurred in patients treated with 5-HT1 agonists, and some have resulted in fatalities. 2-For patients with coronary artery disease (CAD) risk factors, a
cardiovascular evaluation should be performed prior to initiating therapy; for patients who have satisfactorily completed a cardiovascular evaluation, consider administering first dose in a medically supervised setting and performing an ECG immediately following administration.
3-Use with caution; dose adjustment may be considered in patients with severe hepatic impairment, however, no specific guidelines have been suggested.

Points of recommendation

1-This drug should be used only where a clear diagnosis of migraine has been established; if a patient does not respond, the diagnosis of migraine should be reconsidered before treating subsequent attacks.
2-ECG monitoring should be considered in the interval following the first dose in patients with risk factors for coronary artery disease (CAD) who have satisfactorily completed a cardiovascular evaluation, consider periodic cardiovascular evaluation in intermittent long-term users with cardiovascular risk factors.
3-Patients should be informed of the possibility of developing medication overuse headaches.
4-This drug may impair judgment, thinking, or motor skills; have patient avoid driving or operating machinery until adverse effects are determined.

Pregnancy level

C


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