Difference between rizatriptan and sumatriptan

Introduction

Repeated attacks of headaches affecting mostly one side of the head associated with other symptoms such as nausea and vomiting are termed as migraine. Between episodes of migraine, the person is symptom free. One of the most common medications given for symptoms of headache is triptans. This class of drugs includes almotriptan, eletriptan, sumatriptan, rizatriptan and some others.

Sumatriptan was the first of the triptans to be used and the others followed. They are medically known as ‘serotonin agonists’. Serotonin is a chemical in the brain which attaches to specific cells in the body and once it’s bound, it can produce a set of reactions based on which cell is stimulated. Triptans cause the same effect as body’s own serotonin does. Thus, when taken during an attack of migraine, it produces a narrowing of the dilated blood vessels in the brain which were responsible for the migraine headache. It is important to note that triptans cannot be taken to prevent an attack of migraine but should be consumed during the course of the attack. Triptans are available only in a pharmacy through a prescription.

Sumatriptan and rizatriptan belong to this class and are commonly used in treatment of migraine. Though they belong to the same class of drugs they have certain differences especially in the mechanism of action.

Difference in mechanism of action

Sumatriptan and rizatriptan when taken orally, take some amount of time to be absorbed into the blood stream and reach the brain to act. The time taken for the drug to reach the blood and become available to the tissues is much lesser in rizatriptan than sumatriptan. Rizatriptan is available within an hour as compared to sumatriptan that takes about 2-2.5 hours. Even the availability of drug compound when administered is more in rizatriptan. Due to this, rizatriptan has a faster onset of relief compared to sumatriptan. The time taken from drug intake to relief of symptoms is much faster in rizatriptan. Sumatriptan takes about an hour for onset of action as compared to rizatriptan which takes about 30 minutes.

Difference in chemical structure

Rizatriptan does not have a sulphur group in its basic chemical structure which is present in sumatriptan. The sulphur group can lead to allergy though no documented evidence shows allergy with sumatriptan. Rizatriptan’s molecular structure has an affinity for lipids or fats and tends to dissolve in them faste; thus having a higher degree of penetration in central nervous system.

Difference in formulations, dose and dosage

Sumatriptan is available in the form of tablets, injections or nasal sprays. Rizatriptan is available in the form of tablets or orally disintegrating tablets.

It has been seen that 10mg rizatriptan is much more effective than a 50 or 100mg of sumatriptan. Overall response is more consistent with rizatriptan.

Another important point to note is that rizatriptan is available as an orally dissolving tablet, such that the moment it comes in contact with the tongue it dissolves rapidly .Thus, there is no need to take water. Its easy administration makes it a preferred choice.

Both these drugs have similar side effects and tolerance levels and should not be taken without medical supervision.

Summary

Sumatriptan and rizatriptan are part of the Triptans class of drugs used in treatment of migraine. Sumatriptan was the pioneer drug , later other triptans like rizatriptan were produced. Rizatriptan is faster acting compared to sumatriptan. Sumatriptan contains sulphur and might cause allergy.