Eletriptan

Eletriptan is a prescription drug used for the treatment of migraine headaches. It belongs to a family of antimigraine drugs called triptans. Other members of this family include sumatriptan (Imitrex) and zolmitriptan (Zomig). Triptans reduce the pain of a migraine by activating serotonin receptors on blood vessels and nerve cells. The U.S. Food and Drug Administration approved eletriptan in December 2002.

Other Names
Eletriptan is marketed by Pfizer under the following names:


 * Relpax in the United States and Canada
 * Relert in the United Kingdom

Uses
Eletriptan is used to treat migraines with or without aura in adults. However, it is not used to prevent attacks.

How is Taken
Eletriptan is available in 20-mg, 40-mg, and 80-mg (as Relert) oral tablets. Single doses of either strength are effective. If pain relief is not sufficient after one dose, another can be taken at least two hours after the first. Serious adverse reactions can occur if more than 80 mg of eletriptan is taken within a 24-hour period.

How Works
The pain and other symptoms of migraines are caused by dilated blood vessels and inflammation in the brain. Dilated (widened) blood vessels leak fluid, which accumulates and causes pain. Inflammation is caused by chemicals released from nerves. Serotonin, or 5-hydroxytryptamine, is a neurotransmitter. Neurotransmitters carry signals from one neuron to another neuron, a muscle, or other tissue. In the brain, serotonin constricts blood vessels and reduces release of inflammatory chemicals and other pain mediators from nerves.

Like all other triptans, eletriptan binds to and activates serotonin receptors. In this way, it acts like serotonin–it constricts blood vessels and prevents the release of chemicals that promote inflammation.

How the Body Affects
Eletriptan is well absorbed, with peak circulating levels occurring approximately 1.5 hours after dosing. The time required for the concentration of the drug in the blood to be reduced by half, the half-life, is approximately four hours. Eletriptan is primarily metabolized in the liver by the enzyme CYP3A4. It is then excreted in the urine.

Side Effects
Below are the most common side effects of eletriptan:


 * feelings of weakness
 * nausea
 * dizziness
 * somnolence (sleepiness)

Risks and Precautions
Eletriptan can increase blood pressure in people with mild or moderate kidney impairment. Lower doses reduce the risk of toxicity in these people.

The elevated blood pressure caused by the drug also poses significant risk in people with the following conditions:


 * pre-existing, uncontrolled high blood pressure
 * coronary heart disease
 * angina (chest pain)
 * abnormal heartbeats and/or abnormal electrical conduction in the heart (arrythmias)
 * heart failure

Drug Interactions
One of the most potentially harmful interactions with eletriptan occur with other drugs that potentiate the action of serotonin. In the most serious interaction, the serotonin syndrome can result. This syndrome, which can be life-threatening, is due to over-activation of serotonin receptors. Symptoms of the syndrome include confusion, hallucinations, rapid heart beat, feeling faint, fever, sweating, muscle spasm, difficulty walking and/or diarrhea. The list of drugs below activate the serotonin system and could interact with eletriptan:


 * the selective serotonin reuptake inhibitor antidepressants (e.g., paroxetine (Paxil), fluoxeitne (Prozac))
 * the serotonin-norepinephrine reuptake inhibitor mood stabilizers (e.g., venlafaxine (Effexor))
 * other triptans (e.g., sumatriptan, zolmitriptan)
 * ergotamine-containing or ergot-type medications (e.g., dihydroergotamine [DHE] or methysergide)
 * monoamine oxidase inhibitors (MAO inhibitors like selegiline)

Drugs that inhibit the liver enzyme CYP3A4, including ketoconazole (Nizoral), itraconazole (Sporanox), and erythromycin, could elevate blood concentrations of eletirptan by reducing its metabolism.

Overdosage
Some patients in clinical trials had received single, 120 mg doses of eletriptan without any side effects. Overdosage has the potential to have harmful cardiovascular consequences, such as high blood pressure or more serious cardiovascular events.

Research
One study compared the effectiveness of eletriptan with that of sumatriptan and placebo. Response rates two hours after taking one of the three drugs were 24% for placebo, 55% for 100 mg sumatriptan, 54% for 20 mg eletriptan, 65% for 40 mg eletriptan, and 77% for 80 mg eletriptan. The highest dose of eletriptan had a significantly greater response rate than did sumatriptan.