Pharmacology
Summary
The lesson focused on the treatment and prophylaxis of migraines, which are characterized by severe, throbbing, unilateral headaches that can last from a few hours to a few days. These headaches can be categorized into classic migraine, characterized by a variable aura that can involve nausea, vomiting, visual scotomas, and speech abnormalities, and common migraine, which lacks the aura but comes with a similar type of headache. The pain experienced is due to the activation of the trigeminal nerve afferents which innervate intracranial arteries, particularly in the meninges, leading to the release of vasoactive neuropeptides such as calcitonin gene-related peptide, substance P, and neurokinin A. This induces vasodilation and protein extravasation, causing neurogenic inflammation.
The lesson elucidated the role of Sumatriptan and related agents as the first line of therapy for acute severe migraine attacks in most patients. Sumatriptan is selective agonists of the 5-HT 1B and 5-HT 1D receptors located on the meningeal vessels, the trigeminal nerve, and the brainstem. This activation directly on cerebral and meningeal vessels may induce vasoconstriction, attenuating inflammation, and decreasing the stretch at pain receptors. Other treatment options mentioned include the use of NSAIDs, calcium channel blockers, beta blockers, valproic acid, topiramate, and tricyclic antidepressants such as amitriptyline, many of which have proven to be effective for migraine prevention.
Lesson Outline
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FAQs
Triptans are specialized medications developed primarily for migraine relief. They achieve their effect by targeting and activating 5-HT1B and 5-HT1D receptors present in the brain's blood vessels and nerve endings. This action leads to the constriction of dilated blood vessels and dampens inflammation, consequently reducing migraine-associated pain.
Nonsteroidal anti-inflammatory drugs (NSAIDs) are valuable in migraine treatment as they diminish inflammation and offer pain respite. They can complement other migraine therapies to boost their efficiency. For prevention, NSAIDs serve as an alternative when other preventive strategies are contraindicated or lead to adverse reactions.
The trigeminal nerve is pivotal in migraine pathophysiology. During a migraine episode trigeminal afferents are activated, prompting the release of vasoactive peptides (CGRP, substance P, neurokinin A) onto meningeal vessels, resultin in vasodilation and protein extravasation. Triptans intervene by binding 5-HT1b and 5-HT1d receptors on the meningeal vessels, which helps minimize this inflammatory response and alleviating pain.
