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Rizatriptan

Rizatriptan is a serotonin receptor agonist belonging to the group of triptans, and is approved as a pharmaceutical for the treatment of migraine headaches. It is currently offered in the form of tablets and Rizatriptansublingual tablets under the trade name Maxalt and Maxalt ® ® lingua by the manufacturer, MSD Sharp & Dohme.

The admission was made in 1998 in the U.S. by the FDA and in the same year and in Germany by the Federal Institute for Drugs and Medical Devices.

Rizatriptan is a prescription drug.

Pharmacology

Pharmacodynamics
Rizatriptan, like the other triptans is an approved Serotoninagonist. It acts on the agonist 5-HT1B receptors that result in the vasoconstriction or narrowing of the intracranial blood vessels.

An additional action on the mechanisms of the 5-HT1D receptor-mediated inhibition is postulated on the distribution of vasoactive neuropeptides, and the central pain transmission in the brain stem.

Pharmacokinetics
The absorption of rizatriptan runs relatively fast, the calculated for the maximum plasma concentration of Tmax is approximately 50 minutes, which provides a high bio-availability achieved by about 45 per cent take up and a half-life of two to three hours.

For peroral administration of 10 milligrams the onset is after 30 minutes.

Dosage and administration

Rizatriptan is used in doses of five and ten milligrams in the form of tablets and sublingual tablets.

In both dosage forms, it is in the form of its salt-containing benzoic acid, 7.265 or 14.53 mg rizatriptan benzoate. The standard dose is ten milligrams; a dose of five milligrams should be used in hepatic or renal function.

In general the drug does not act preventively, but it is taken at the first sign of a migraine headache, in general, a single dose is sufficient, but in case of insufficient effect after a two hour period a second dose can be taken.
The total daily dose should not exceed 20 milligrams, in approximately one third of patients; they may have after the first dose a recurrence of headaches, so that a second application is necessary.

Approximately 10 to 20 percent of patients do not respond to treatment with rizatriptan.

Rizatriptan is like all the triptans,it is a weapon of choice for the acute treatment of moderate and severe migraine headaches, due to the risk profile and costs of the drug it is only used in reserve in long-term treatment.

Through frequent use, the drug may also increase the frequency of migraine attacks and lead to a drug-induced permanent headache.

Side-effects

Rizatriptan is generally described as well tolerated with the most common adverse effects include hot flashes, dry mouth and thirst, temporary muscle weakness, dizziness, nausea, weakness and fatigue, further palpitations, tachycardia, and dyspnea.

As life-threatening, but rare side effects these may include heart attack and the provocation and induction of severe arrhythmias, and because of these rare side effects, driving and other potentially dangerous activities should be avoided after administration.

Risk groups and contraindications

The possible contraindications for which the use of rizatriptan should be done with caution, is if the patient has hypertension, diabetes mellitus, peripheral vascular disease and mild to moderate restrictions on the liver or kidney function.

The groups of people most at risk to the negative side effects, are post-menopausal women and smokers. In the presence of heart disease rizatriptan should not be used because of the risk of ischemic conditions, and vasospasm, nor should it be used for angina pectoris in patients with previous heart attacks and strokes, severe restrictions on the liver and kidney function, as well as two special forms of migraine, familial hemiplegic migraine FHM and Basilarmigräne.

Lack of clinical experience is also discouraged of the drug for the use in children and adolescents under the age of 18 and adults over 65, pregnant women and mothers during lactation.

Interactions

A combined use of the drug with other triptans is to be avoided because of the increased effect on the same mechanism of action, and the consequent increased risk of side effects, as well as the combination with ergot derivatives because of an increased vasospasm risk.

The combination of migraine drugs from other classes of compounds should be coordinated with the treating physician. The FDA warns of a potentially life-threatening interaction of the serotonin syndrome, ie an accumulation of too much serotonin in the nervous system, while taking a triptan and an antidepressant from the group of selective serotonin reuptake inhibitors SSRIs or selective serotonin and norepinephrine reuptake inhibitor SNRI.

The symptoms of serotonin syndrome may induce restlessness, hallucinations, loss of coordination, fast heart beat, blood pressure fluctuations, increased body temperature, increased to include reflexes, nausea, vomiting and diarrhoea.

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