Naproxen
Second line non-steroidal anti-inflammatory drug (NSAID)
Mechanism of action: A propionic acid derivative non-steroidal anti-inflammatory drug (NSAID). It is a non-selective inhibitor of cyclooxygenases COX-1 and COX-2, thus results in a decrease in the synthesis of prostaglandins which are involved in pain and inflammatory processes.
Presentation: tablet. Oral suspension & effervescent tablet not available in OUH.
Suggested dose: 250mg – 500mg twice a day for adults over 50kg with normal hepatic and renal function
Co-prescribe proton pump inhibitor (PPI) cover.
Oral absorption: Very high bioavailability, peak plasma concentration at 0.5-3 hours
Protein binding: 99% protein bound, principally to albumin
Metabolism: Naproxen is extensively metabolized in the liver by cytochrome P450 to 6-0-desmethyl naproxen.
Elimination: Metabolites excreted in the urine, with very little of the drug excreted unchanged
Half-life: 12-17 hours
Significant interactions (see the BNF for more interactions):
- Aspirin: NSAIDs competitively inhibit aspirin binding to platelets so antagonise the cardioprotective effect of low-dose aspirin
- Lithium: NSAIDs increase the serum lithium level and reduce lithium clearance, risking acute lithium intoxication
- Anti-hypertensives: NSAIDs compromise the efficacy of anti-hypertensive drugs such as ß-adrenergic blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and diuretics.
- Methotrexate: toxic interaction between naproxen and methotrexate
Further prescribing information (side effects, contraindications, interactions):