Antimigraine Drugs; Uses/Indications, Side Effects, Interactions

Antimigraine Drugs; Uses/Indications, Side Effects, Interactions

Antimigraine drugs are the groups of drug that are used for treatment or prevention of a migraine. A migraine is a primary headache disorder characterized by recurrent headaches that are moderate to severe. Typically, the headaches affect one half of the head, are pulsating in nature, and last from two to 72 hours. Associated symptoms may include nausea, vomiting, and sensitivity to light, sound, or smell. The pain is generally made worse by physical activity. Up to one-third of people have an aura: typically a short period of visual disturbance that signals that a headache will soon occur. Occasionally, an aura can occur with little or no headache following it.

Classifications / Types of Antimigraine

Mechanism of Action of Antimigraine

Their action is attributed to their agonist effects on serotonin 5‑HT1B and 5‑HT1D receptors in blood vessels (causing their constriction) and nerve endings in the brain, and subsequent inhibition of pro-inflammatory neuropeptide release, including CGRP and substance P. Triptans are selective agents for 5-HT1B and 5-HT1D and have low or even no affinity for other types of 5-HT receptors.

5-HT receptors are classified into seven different families named 5-HT1 to 5-HT7. All receptors are G protein-coupled receptors with seven transmembrane domains with the one exception of 5-HT3 receptor which is a ligand-gated ion channel. There is a high homology in the amino acid sequence within each family. Each family couples to the same second messenger systems. Subtypes of 5-HT1 are the 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E, and 5-HT1F receptors. All 5-HT1D receptors are coupled to inhibition of adenylate cyclase. 5-HT1Band 5-HT1D receptors have been difficult to distinguish on a pharmacological basis. After cloning two distinct genes for 5-HT1B and 5-HT1D receptors, a better insight into distribution and expression in different tissues was gained, except in brain tissue where they are overlapping in several areas

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Most mammalian species, including humans, have 5-HT1D binding sites widely distributed throughout the central nervous system. 5-HT1D receptors are found in all areas of the brain but they differ in quantity at each area. An important initiator of head pain is suggested to be the activation of trigeminovascular afferent nerves which upon activation releases neuropeptides such as CGRP, substance P and neurokinin A. Also they are thought to promote neurogenic inflammatory response important for sensitization of sensory afferents, and also transmission and generation of head pain centrally. 5-HT1D has been found responsible for inhibition of neurogenic inflammation upon administration with sumatriptan and other related compounds that act on prejunctional 5-HT1D receptors.

All triptans, like the older drug dihydroergotamine, have agonistic effects on the 5-HT1D receptor. Comparison of sumatriptan and dihydroergotamine showed that dihydroergotamine has high affinity and sumatriptan has a medium affinity for 5-HT1D. Triptans have at least three modes of action. These antimigraine mechanisms are:

  1. vasoconstriction of pain-producing intracranial extracerebral vessels by a direct effect on vascular smooth muscle. Sumatriptan and rizatriptan have been shown to cause vasoconstriction in the human middle meningeal arteries.
  2. inhibition of vasoactive neuropeptide release by trigeminal terminals innervating intracranial vessels and the dura mater. The trigeminocervical complex has 5-HT1D receptors that bind dihydroergotamine and triptans in humans. Rizatriptan has been shown to block dural vasodilation and plasma protein extravasation by inhibiting the release of CGRP via activation of receptors on preganglionic trigeminal sensory nerves terminals. Sumatriptan is shown to inhibit potassium stimulated CGRP secretion from cultured trigeminal neurons in a dose dependent manner and may also inhibit the release of substance P.
  3. inhibition of nociceptive neurotransmission within the trigeminocervical complex in the brainstem and upper cervical spinal column. Rizatriptan has central trigeminal antinociceptive activity.
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Other possibilities of triptans in antimigraine effects are modulation of nitric oxide-dependent signal transduction pathways, nitric oxide scavenging in the brain, and sodium-dependent cell metabolic activity.

Indications of Antimigraine

  • Migraines

Contra-Indications of Antimigraine

Do not take almotriptan within 24 hours before or after using another migraine headache medicine

Side Effects of Antimigraine

The most common

More common

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Rare

Drug Interactions of Antimigraine

Antimigraine drugs may interact with the following drug, supplements, & may change the efficacy of the drug

References

Antimigraine Drugs

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