Naproxen
Class: non-steroidal anti-inflammatory drug (NSAID)
Indications (NB some may be unlicensed): pain associated with inflammation (including bone pain), dysmenorrhoea, itch, sweating; acute migraine; post-operative pain; acute gout
Contraindications/cautions: Sensitivity to aspirin or other NSAIDs (includes asthma, angioedema, urticaria or rhinitis precipitated by aspirin or NSAID); GI ulceration (active or history of), severe heart failure; renal or hepatic impairment (avoid in severe impairment) and caution in other cardiac conditions. Caution in use in the elderly & those with coagulation defects
Adverse reactions: common: GI discomfort, nausea, diarrhoea, indigestion; can lead to GI ulceration (caution: if elderly, on steroids or aspirin), increased blood pressure, headache, dizziness, sodium & fluid retention less common: rash, nephrotoxicity, hepatitis, oedema, tinnitus, proctitis (rectal administration). NB Inhibits platelet aggregation – may prolong bleeding time
Metabolism/clearance: metabolised by metabolising enzyme CYP2C8/9 mainly in the liver
Interactions:
- increased clinical effect/toxicity of naproxen (due to increased blood concentrations) may occur with some CYP metabolising enzyme inhibitors (see above) e.g. fluconazole, ketoconazole, voriconazole
- decreased clinical effect/toxicity of naproxen (due to decreased blood concentrations) may occur with some CYP metabolism enzyme inducers (see above) e.g. phenobarbitone, phenytoin, rifampicin
- increased clinical effect/toxicity of lithium, digoxin, methotrexate and warfarin may occur with naproxen due to increased concentrations of these drugs via kidney excretion competition so monitor
- decreased clinical effects of diuretics (e.g. furosemide) and beta blockers (e.g. propranolol) may occur with naproxen
- increased risk of renal toxicity and hyperkalaemia with ACE inhibitors may occur with naproxen
- additive risk of bleeding may occur with warfarin and heparin in combination with naproxen
| Dosing: | ||
|---|---|---|
| oral: | normal release | 500 to 1,000 mg per day in 2 divided doses or 275 mg every 6 to 8 hours (max 1,375 mg) |
| sustained release | 750 to 1,000 mg per day as a single dose | |
| subcut: | not available | |
| rectal: | not available (try diclofenac) | |
Syringe driver: not available
Mechanism of action: NSAIDs reduce prostaglandin production by inhibiting cyclo-oxygenase, resulting in analgesic, anti-inflammatory and anti-pyretic effects
Peak effect: oral normal release: 2 to 4 hours
Duration: 7 hours