Comparative Pharmacology
Head-to-head clinical analysis: ACETAMINOPHEN AND IBUPROFEN versus ASPIRIN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ACETAMINOPHEN AND IBUPROFEN versus ASPIRIN.
ACETAMINOPHEN AND IBUPROFEN vs Aspirin
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Acetaminophen is a centrally acting analgesic and antipyretic whose exact mechanism is not fully understood, but is thought to involve inhibition of cyclooxygenase (COX) in the brain and modulation of cannabinoid receptors. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that non-selectively inhibits COX-1 and COX-2, reducing prostaglandin synthesis.
Irreversibly inhibits cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) via acetylation, reducing prostaglandin and thromboxane A2 synthesis. Also activates lipoxin biosynthesis (inflammation resolution).
Oral: Acetaminophen 325 mg and ibuprofen 200 mg, 1-2 tablets every 6 hours as needed, not exceeding 6 tablets/24 hours.
325-650 mg PO q4-6h prn; max 4 g/day
None Documented
None Documented
Acetaminophen: 2-3 hours (normal hepatic function). Ibuprofen: 2-4 hours (immediate-release); prolonged in overdose or hepatic impairment.
30 minutes for aspirin (parent drug); salicylic acid: 2-3 hours after low doses, 15-30 hours after high doses due to saturable metabolism and renal reabsorption. Clinical context: prolonged half-life in overdose, renal impairment, and elderly patients.
Acetaminophen: renal excretion of metabolites (glucuronide 55%, sulfate 30%, cysteine/mercapturate <10%); <5% unchanged. Ibuprofen: renal excretion of metabolites (conjugates) 90%; <10% unchanged; minor biliary/fecal.
Renal excretion of salicylates (75-85% as salicyluric acid, 10% as free salicylic acid, 5-10% as glucuronide conjugates); dose-dependent, with renal clearance decreasing at higher doses due to saturation of metabolic pathways. Biliary/fecal elimination is minimal (<5%).
Category D/X
Category C
NSAID
NSAID / Antiplatelet