1. Why sumatriptan is preferred over ergotamine in acute migraine attack

• Receptor selectivity: Sumatriptan is a selective 5-HT1B/1D receptor agonist, causing selective constriction of cranial/meningeal vessels and inhibiting trigeminal neuropeptide (CGRP) release. Ergotamine is a non-selective agonist at 5-HT, alpha-adrenergic, and dopaminergic receptors, producing widespread vasoconstriction (Harrisons Principles of Internal Medicine, 22E).
• Better efficacy and tolerability: Sumatriptan gives faster, more reliable relief with fewer side effects; ergotamine causes more nausea, vomiting and vasospasm-related adverse effects (Lippincott Illustrated Reviews - Pharmacology).
• Safety margin: Ergotamine has a narrow therapeutic index, cumulative toxicity with repeated dosing (ergotism - peripheral vasospasm, gangrene), and is contraindicated in pregnancy, peripheral vascular disease and hypertension, whereas sumatriptan has a more predictable, self-limiting side-effect profile.

2. Aspirin may precipitate bronchial asthma in susceptible individuals

• Aspirin inhibits cyclo-oxygenase (COX), blocking the synthesis of prostaglandins including PGE2, which normally suppresses the lipoxygenase pathway.
• With COX blocked, arachidonic acid is shunted into the lipoxygenase pathway, causing overproduction of cysteinyl leukotrienes (LTC4, LTD4, LTE4) - potent bronchoconstrictors and mucus secretagogues (Robbins Pathologic Basis of Disease; Katzung's Pharmacology).
• This produces "aspirin-exacerbated respiratory disease" (Samter's triad: asthma, nasal polyps, aspirin sensitivity) - an attack of bronchospasm in susceptible (usually atopic/polyp-bearing) individuals, not a true IgE allergy.

3 & 4. Why aspirin is not recommended / avoided in children with viral infections (viral fever)

• Epidemiological studies linked aspirin use during viral illnesses (influenza, varicella/chickenpox) in children to Reye's syndrome - an acute, potentially fatal encephalopathy with fatty degeneration and failure of the liver (Firestein & Kelley's Textbook of Rheumatology; Essentials of Forensic Medicine and Toxicology).
• The mechanism is thought to involve aspirin-induced mitochondrial injury in hepatocytes, impairing beta-oxidation and the urea cycle, precipitating hepatic failure with cerebral edema, in the setting of viral infection.
• Because of this risk, aspirin is contraindicated in children/adolescents under about 12-16 years with viral fever; paracetamol is used instead as the safe antipyretic.

5. Drugs used for prophylaxis of migraine and management of acute attack

• Beta-blockers - propranolol, metoprolol (drugs of choice)
• Calcium channel blockers - flunarizine, verapamil
• Antiepileptics - topiramate, sodium valproate/divalproex
• Antidepressants - amitriptyline, venlafaxine
• Anti-CGRP monoclonal antibodies / botulinum toxin A (for chronic migraine) (Lippincott Illustrated Reviews - Pharmacology; Kaplan & Sadock's Comprehensive Textbook of Psychiatry)

• Mild-moderate: NSAIDs (aspirin, naproxen, ibuprofen) or paracetamol, often with an antiemetic (metoclopramide)
• Moderate-severe: Triptans (sumatriptan, zolmitriptan, etc.) - first line; combining a triptan with naproxen improves response and reduces recurrence
• Ergotamine/dihydroergotamine - reserved for cases unresponsive to triptans (Harrison's; Katzung's)

6. Why sumatriptan should be avoided in patients with coronary artery disease

• Sumatriptan acts on 5-HT1B receptors present not only on cranial vessels but also on coronary arteries, causing coronary vasoconstriction/spasm (Fuster and Hurst's The Heart; Bradley and Daroff's Neurology in Clinical Practice).
• In a patient with underlying atherosclerotic CAD, this added vasospasm can reduce coronary flow enough to precipitate angina, myocardial ischemia, or infarction, and can provoke arrhythmias.
• Hence sumatriptan (and other triptans) are contraindicated in patients with known CAD, coronary vasospasm (Prinzmetal's angina), uncontrolled hypertension, or significant cardiovascular risk factors (Katzung's Basic and Clinical Pharmacology; ROSEN's Emergency Medicine).

7. Why aspirin is contraindicated in bronchial asthma

• Aspirin inhibits COX-1, decreasing the bronchodilator/anti-inflammatory prostaglandin PGE2.
• Arachidonic acid metabolism is shunted toward the 5-lipoxygenase pathway, generating excess cysteinyl leukotrienes, which are far more potent bronchoconstrictors than histamine and also increase mucus secretion and vascular permeability.
• In sensitive asthmatics (particularly those with nasal polyps/chronic rhinosinusitis - "aspirin triad"), even small doses can trigger severe, sometimes life-threatening bronchospasm within minutes to hours, so aspirin (and other non-selective COX inhibitor NSAIDs) is contraindicated in these patients (Robbins Pathologic Basis of Disease, p. Drug-Induced Asthma; Fishman's Pulmonary Diseases and Disorders).