Pharmacology Cheat Sheet
Autacoids, Inflammation and Pain
NSAIDs, paracetamol, gout, DMARDs and migraine pharmacology for NEET-PG: aspirin mechanism, NAC antidote, methotrexate rules, and triptan facts.
MedNext Academy | 3 min read
Clinically reviewed by Dr Shameer Deen, MBBS, MS, MRCS
Autacoids, Inflammation and Pain
NSAIDs, paracetamol, gout, DMARDs and migraine pharmacology for NEET-PG: aspirin mechanism, NAC antidote, methotrexate rules, and triptan facts.
Autacoids and anti-inflammatory drugs covering histamine, serotonin, prostaglandins, NSAIDs, paracetamol, gout therapy, DMARDs, and migraine management.
High-yield lines
- Aspirin is unique in irreversibly acetylating cyclooxygenase, so a single low dose abolishes platelet thromboxane A2 for the platelet's lifespan; all other NSAIDs are reversible.
- Naproxen is the most cardiovascular-neutral NSAID, whereas diclofenac carries the highest cardiovascular risk among traditional agents.
- Paracetamol is the analgesic of choice in children, pregnancy, peptic ulcer disease, and aspirin or NSAID hypersensitivity.
- The paracetamol antidote is N-acetylcysteine, most effective within 8 to 10 hours of ingestion, and treatment is guided by the Rumack-Matthew nomogram.
- Colchicine is the drug of choice for acute gout, acute pericarditis, and it also closes a patent ductus arteriosus when given as indomethacin.
- Allopurinol and febuxostat should never be started during an acute gout flare because urate mobilisation worsens the attack.
- Methotrexate is the anchor DMARD in rheumatoid arthritis, taken weekly with folic acid, and its overdose antidote is folinic acid (leucovorin).
- Every patient must be screened for latent tuberculosis and hepatitis B before starting any biologic, especially a TNF inhibitor.
- Propranolol is the best-evidenced migraine prophylactic, while verapamil is the drug of choice for cluster-headache prophylaxis.
- Sumatriptan given subcutaneously has the fastest onset, and frovatriptan has the longest half-life, favouring menstrual migraine.
- Cimetidine has the worst CYP450 interaction profile and antiandrogenic effects, whereas famotidine is the most potent and cleanest H2 blocker.
- Cyproheptadine is the antidote in serotonin syndrome, which develops fast with hyperreflexia and clonus after a serotonergic drug.
- Misoprostol is a PGE1 analogue that protects gastric mucosa, and alprostadil (PGE1) keeps the ductus arteriosus patent in ductal-dependent congenital heart disease.
- Aspirin-exacerbated respiratory disease combines asthma, nasal polyps, and NSAID sensitivity, and responds to leukotriene modifiers.
Mapped competency codes
- PH1.16
Continue into the full chapter
This summary maps to PH3-autacoids-and-anti-inflammatory-drugs.
Frequently Asked Questions
Why does low-dose aspirin work as an antiplatelet for the platelet lifespan?
Aspirin irreversibly acetylates cyclooxygenase, and anucleate platelets cannot synthesise new enzyme, so the effect lasts about 7 to 10 days.
What is the antidote for paracetamol overdose?
N-acetylcysteine, which replenishes glutathione and conjugates NAPQI; it is most effective within 8 to 10 hours of ingestion.
Which NSAID has the highest cardiovascular risk and which is safest?
Diclofenac carries the highest cardiovascular risk, while naproxen is the most cardiovascular-neutral.
How is serotonin syndrome distinguished from neuroleptic malignant syndrome?
Serotonin syndrome is fast with hyperreflexia and clonus, while NMS is slow with lead-pipe rigidity and hyporeflexia; the antidote for serotonin syndrome is cyproheptadine.
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