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Relpax for Migraine

Last updated on June 1, 2023

Brand Name Drug: Relpax
Active Ingredient Drug:  eletriptan
Indication: Treatment of symptoms of acute migraine headache
Company Name:  Pfizer Inc


During a migraine headache attack, brain activity changes induce inflammation of cerebral blood vessels and nerves. Attacks may be triggered by alcohol, certain foods, too much or too little sleep, menstruation, emotional stress, or environmental factors. Sumatriptan was the first serotonin agonist for treating migraine, but a new faster, more effective antimigraine drug: Relpax (eletriptan). Manufactured by Pfizer Inc., Relpax is also a serotonin agonist but its affinity for these receptors is different from that of sumatriptan.

How It Works

The triptan antimigraine drugs are derived from the serotonin molecule. They act on 5-hydroxytryptamine (HT) 1B/1D receptors on blood vessels, trigeminal neurons, and the trigeminal nucleus caudalis, causing constriction of extracerebral intracranial vessels, abolition of dural extravasation and neurogenic inflammation, and inhibition of trigeminal neuronal discharge. Relpax has more than a 6-fold higher affinity than sumatriptan at the 5-HT1D receptor and more than a 3-fold greater affinity at the 5-HT1B receptor. Relpax also binds potently to the 5-HT1F receptor.

New drug trials suggest that Pfizer’s drug Relpax (eletriptan) may be one of the most effective drugs for the treatment of migraine headaches. Researchers at Memorial University in St. John’s Newfoundland, conducted a randomized trial in 774 patients using 40 mg and 80 mg doses of eletriptan compared to 50 and 100 mg doses of the drug sumatriptan. It was found that 67 percent of the eletriptan 80 mg patients and 64 percent of the eletriptan 40 mg patients were pain-free two hours after dosing, compared to 53 percent of the patients who received sumatriptan 100 mg and 50 percent of those who received 50 mg. Two hours after dosing, 65 percent of patients in the eletriptan 80 mg group were able to resume at least some normal activities, compared to just 51 percent of patients in the 100 mg sumatriptan group. Results of the trials were presented by Dr. William Pryse-Phillips, neurologist and director of the migraine clinic at Memorial University, at the 9th Congress of the International Headache Society meeting in Barcelona, Spain.

Relpax: Clinical Study Results

RelpaxOne study compared the efficacy of Relpax with that of sumatriptan and placebo in 692 patients who suffered from migraine headaches. Subjects were randomized to receive oral Relpax (20 mg, 40 mg, or 80 mg), sumatriptan 100 mg, or placebo. Within 1 hour of administration, pain was reportedly reduced from moderate-severe to mild-none in 24% of those taking 20 mg Relpax, 38% of those taking 40 mg Relpax, and 41% of patients taking 80 mg Relpax, compared to 20% of patients taking 100 mg sumatriptan and 12% of subjects taking placebo – a significant difference.

At 2 hours, 77% of the Relpax group reported mild/no pain versus 55% of the sumatriptan group, while at 4 hours the corresponding values were 58% for Relpax and 46% for sumatriptan. Patient acceptability was 64% for 100 mg sumatriptan and 20 mg Relpax, 74% for 40 mg Relpax, and 84% for 80 mg Relpax, indicating that 80 mg of Relpax is the dose that patients preferred most.

Another study showed that Relpax is as effective in treating migraine during menstruation as it is during non-menstruation. A group of 454 women with migraine received 20 mg, 40 mg, or 80 mg Relpax, 100 mg of sumatriptan, or placebo. The results showed that 41% to 71% of women taking Relpax for a menstrually-related migraine reported a reduction in headache pain from moderate-severe to mild-none at 2 hours, as did 55% to 76% of women taking Relpax who were not menstruating. For sumatriptan, the 2-hour headache response was 54%. None of the results differed significantly from each other.

What the Patient Should Know

Adverse side effects associated with serotonin agonists include warmth and tingling, dizziness, nausea or vomiting, and chest or throat pain or tightness. As with all drugs, the patient should inform his or her healthcare provider of any other medications being taken, since serotonin agonists may interact with certain antidepressants and other medications.

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