Ibuprofen
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ibuprofen pharmacology mechanism of action dosing indications
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ibuprofen adverse effects contraindications drug interactions
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Ibuprofen
Ibuprofen is a non-steroidal anti-inflammatory drug (NSAID) — one of the most widely used analgesic, anti-inflammatory, and antipyretic medications available both over-the-counter and by prescription.
Mechanism of Action
Ibuprofen nonselectively and reversibly inhibits COX-1 and COX-2 (cyclooxygenase isozymes), blocking the conversion of arachidonic acid into prostaglandins and thromboxane A2. Prostaglandins mediate pain, fever, and inflammation, so inhibiting their synthesis produces ibuprofen's therapeutic effects. (Opioid Prescribing for Analgesia After Common Otolaryngology Operations, p. 19)
Indications
| Category | Examples |
|---|---|
| Pain | Headache, dental pain, musculoskeletal pain, dysmenorrhea, post-operative pain |
| Inflammation | Arthritis (OA, RA), gout, bursitis, tendinitis |
| Fever | Adults and children (>6 months) |
| Other | Pericarditis, patent ductus arteriosus (IV form in neonates) |
Dosing
| Use | Adult Dose | Max Daily Dose |
|---|---|---|
| OTC analgesic/antipyretic | 200–400 mg every 4–6 h | 1,200 mg/day |
| Prescription (pain/inflammation) | 400–800 mg every 6–8 h | 3,200 mg/day |
| Pediatric (fever/pain) | 5–10 mg/kg every 6–8 h | 40 mg/kg/day |
Take with food to reduce GI upset.
Adverse Effects
- Gastrointestinal: GI irritation, ulceration, bleeding (most common concern; COX-1 inhibition reduces protective prostaglandins in gastric mucosa)
- Renal: Reduced renal perfusion, acute kidney injury — especially in volume-depleted or elderly patients
- Cardiovascular: Elevated blood pressure, increased risk of MI and stroke with prolonged use (less so than selective COX-2 inhibitors, but still present)
- Hematologic: Reversible platelet inhibition, increased bleeding time
- Hepatic: Transaminase elevation (rare)
- Hypersensitivity: NSAID-exacerbated respiratory disease (aspirin/NSAID-sensitive asthma), urticaria, angioedema
Contraindications
- Active peptic ulcer disease or GI bleeding
- Severe renal or hepatic impairment
- History of NSAID/aspirin-induced hypersensitivity (asthma, urticaria)
- Third trimester of pregnancy (causes premature closure of ductus arteriosus)
- Perioperative use in CABG surgery
- Heart failure (can worsen fluid retention)
Key Drug Interactions
| Drug | Interaction |
|---|---|
| Warfarin / anticoagulants | Increased bleeding risk |
| Aspirin (low-dose) | Ibuprofen can competitively block aspirin's irreversible COX-1 binding, reducing cardioprotective effect |
| ACE inhibitors / ARBs | Reduced antihypertensive effect; increased AKI risk ("triple whammy" with diuretics) |
| Diuretics | Reduced diuretic efficacy; risk of AKI |
| Lithium / Methotrexate | Reduced renal clearance → toxicity |
| SSRIs | Additive GI bleeding risk |
Special Populations
- Elderly: Use with caution — higher risk of GI bleed and renal impairment; consider gastroprotection (e.g., PPI)
- Pregnancy: Safe in 1st–2nd trimester with caution; avoid in 3rd trimester
- Children <6 months: Not recommended
- CKD/Heart failure: Avoid if possible; use lowest effective dose for shortest duration if necessary
Comparison to Other NSAIDs
| Drug | COX selectivity | GI risk | Cardiovascular risk | Duration |
|---|---|---|---|---|
| Ibuprofen | Non-selective | Moderate | Lower than COX-2 inhibitors | Short-acting (4–8 h) |
| Naproxen | Non-selective | Moderate | Lowest among NSAIDs | Long-acting (8–12 h) |
| Celecoxib | COX-2 selective | Lower | Higher | 12–24 h |
| Aspirin | Non-selective (irreversible) | Higher | Protective at low dose | Variable |
Is there a specific aspect of ibuprofen you'd like to go deeper on — dosing in a specific condition, comparison to another drug, or management of an overdose?
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