Neurosurgery notes/Pharmacology/Anti-inflammatory/NSAID

NSAID

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Anti-inflammatory

Arachidonic acid pathways

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Nonsteroidal anti-inflammatory drugs (NSAIDs)

  • Ibuprofen, naproxen, indomethacin, ketorolac, diclofenac, meloxicam, piroxicam
  • Mechanism
    • Reversibly inhibit cyclooxygenase (both COX‑1 and COX‑2), block prostaglandin synthesis.
  • Clinical uses
    • Antipyretic, analgesic, anti‑inflammatory; indomethacin is used to close PDA.
  • Adverse effects
    • Interstitial nephritis, gastric ulcer (prostaglandins protect gastric mucosa), renal ischemia (prostaglandins vasodilate afferent arteriole), aplastic anemia.

Aspirin

  • Mechanism
    • NSAID that irreversibly inhibits cyclooxygenase (both COX‑1 and COX‑2) via covalent acetylation → ⬇️ synthesis of TXA₂ and prostaglandins; ⬆️ bleeding time; no effect on PT, PTT; effect lasts until new platelets form.
  • Clinical uses
    • Low dose (<300 mg/day): ⬇️ platelet aggregation;
    • Intermediate dose (300-2400 mg/day): antipyretic and analgesic;
    • High dose (2400-4000 mg/day): anti‑inflammatory.
  • Adverse effects
    • Gastric ulceration, tinnitus (CN VIII), allergic reactions (especially in patients with asthma or nasal polyps). Chronic use → acute kidney injury, interstitial nephritis, GI bleeding. Risk of Reye syndrome in children with viral infection. Toxic doses → respiratory alkalosis early, but transition to mixed metabolic acidosis-respiratory alkalosis. Overdose treated with sodium bicarbonate, NaHCO₃.
  • Aspirin and ibuprofen have well-defined antiplatelet effects.

Celecoxib

  • Mechanism
    • Reversibly and selectively inhibits cyclooxygenase (COX) isoform 2 (”Selecoxib”), which is found in inflammatory cells and vascular endothelium and mediates inflammation and pain; spares COX‑1, which helps maintain gastric mucosa. Thus, does not have the corrosive effects of other NSAIDs on the GI lining. Spares platelet function as TXA₂ production is dependent on COX-1.
  • Clinical use
    • Rheumatoid arthritis and osteoarthritis.
  • Adverse effects
    • ⬆️ risk of thrombosis; sulfa allergy.
  • May possibly exert prothombotic effects via inhibition of endothelial cell function (MI and strokes).

Individual features of specific nonsteroidal anti-inflammatory drugs

Drug
Individual feature / comment
Aspirin
Particularly effective for pain due to bone metastasis involving the spine.
Ibuprofen
Noted association with Reye syndrome in children.
Ketorolac
Only parenteral NSAID; very useful in neurosurgical patients highly sensitive to narcotics; usual adult dose 30 mg IV or IM every 6 h, maximum 120 mg/day.
Celecoxib
COX‑2 inhibitor; 200 mg twice daily is considered an effective dose.
  • NSAIDs, nonsteroidal anti-inflammatory drugs; IV, intravenously; IM, intramuscularly