USMLE® Step 1 style questions USMLE
A 50 year old woman with a history of headaches presents with complaints of chest pain. She described the pain as pressure, and tightness in her chest. She said that the pain occurred after taking a drug, the name of which she forgot. The most likely mechanism of this drug is?
Content Reviewers:Yifan Xiao, MD
Contributors:Tanner Marshall, MS, Evan Debevec-McKenney, Victoria S. Recalde, MD, Elizabeth Nixon-Shapiro, MSMI, CMI
Migraines are the second most common primary headache.
They’re often preceded by symptoms like irritability, depression, and fatigue that can begin hours to days before the headache itself. Sometimes there can be an aura where people experience strange smells, lights, visual disturbances, or even hallucinations before the onset of the migraine.
As if this was not bad enough, these headaches tend to come with nausea and vomiting, irritability, and pain or discomfort with lights, sounds, and smells called photophobia, phonophobia, and osmophobia, respectively.
During childhood, individuals can have nausea and vomiting without the headaches; and that’s called an abdominal migraine.
To remember the main features of migraines, you can use the mnemonic POUND, where P stands for pulsatile headache, O stands for one-day duration, U stands for unilateral, N for nausea, and D for disabling.
Although the underlying mechanism causing migraines isn’t well understood, there are some clues.
Concentrations of the neurotransmitter, serotonin, increase during the aura, triggering vasoconstriction, and then decrease to lower-than-normal levels during the migraine attack, triggering vasodilation. This change in the blood vessel size may be a trigger for pain receptors, causing the headache.
Even sleeping too much or too little can sometimes trigger a migraine.
There are two treatment approaches for migraine: acute treatment to help manage the pain; and preventive treatment to keep headaches from happening in the first place, in individuals that have severe, debilitating headaches.
Acutely, pain medications work best if they’re used at the first sign of an attack, during the early symptoms, and aura.
So, triptans should be prescribed when people with mild symptoms don’t respond to analgesics, or when symptoms are moderate to severe.
All of them can be given by mouth, but this may be impractical for people who have nausea or vomiting during the attack. For these situations, subcutaneous injections or a nasal spray of sumatriptan are available.
Side effects are generally mild, and include mild pain or burning sensations at the site of injection, paresthesia, fatigue, or dizziness, when given per orally.
Also, as it causes coronary vasospasm, it can bring about a type of chest pain called angina. Although it’s an uncommon side effect, that’s why triptans are contraindicated in people with hypertension, coronary artery disease, prinzmetal angina, and peripheral vascular disease.
It can also rarely cause myocardial ischemia or infarction, and arrhythmias as well.
Now, when used together with other serotonin receptor agonists, triptans can induce a serotonin syndrome, that comprises of cognitive symptoms, like headache, hallucinations, or coma; somatic symptoms, like tremors or hyperreflexia; and autonomic symptoms like tachycardia, nausea, diarrhoea, shivering, and sweating. So, people who have recently been given ergot alkaloids or other serotonin agonists mustn’t use triptans, at least for 24 hours.
Ergots are also agonist at 5-HT serotonin receptors. However, they're not specific for 5-HT1 receptors, and that means they have more side effects than triptans.
For example, when they stimulate 5HT3 receptors in the vomiting center of the brain, they can trigger nausea or vomiting.
In a similar aspect, as ergot stimulate contraction of the smooth muscle in the wall of blood vessels, they also stimulate contraction of the uterine smooth muscle, an oxytocic effect that can lead to premature labor in pregnant women, causing fetal distress and miscarriage. So, they’re contraindicated during pregnancy.
- "Katzung & Trevor's Pharmacology Examination and Board Review,12th Edition" McGraw-Hill Education / Medical (2018)
- "Rang and Dale's Pharmacology" Elsevier (2019)
- "Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th Edition" McGraw-Hill Education / Medical (2017)
- "Treatment of acute migraine headache" Am Fam Physician (2011)
- "Migraine Headache Prophylaxis" Am Fam Physician (2019)
- "Spotlight on Anti-CGRP Monoclonal Antibodies in Migraine: The Clinical Evidence to Date" Clin Pharmacol Drug Dev (2017)
- "Triptans and ergot alkaloids in the acute treatment of migraine: similarities and differences" Expert Review of Neurotherapeutics (2013)
- "The pathophysiology of migraine: implications for clinical management" Lancet Neurol (2018)