Naproxen

Pronunciation

Naproxen 250mg

Introduction

Generic Name 藥名	HA Code 藥物代碼	Classification藥物分類
Naproxen Sodium Tablet 275mg		P1S1S3

Mechanism of Action

Non-opioid Analgesic (NSAID) Anti-inflammatory agent, Nonselective COX inhibitor, inhibits COX-1 and COX-2

Dosage

In the treatment of rheumatic disorders:

Oral: 500 mg to 1 g daily either as a single dose or in 2 divided doses.

In other painful conditions such as dysmenorrhea and acute musculoskeletal disorders:

Oral: initially 500 mg, followed by 250 mg every 6 to 8 hours, up to a maximum daily dose of 1.25 g on the first day and 1 g thereafter.

In acute gout: Oral: initial dose 750 mg followed by 250 mg every 8 hours

Naproxen has been given rectally in similar doses to those used orally.

Administration in children

In the treatment of juvenile idiopathic arthritis for children aged 2 years and over:

Oral: 10 mg/kg daily in 2 divided doses.

For musculoskeletal disorders,

oral: 5 mg/kg twice daily (maximum of 1 g daily).

Side Effects

As for NSAIDs in general.

Naproxen suppositories can cause rectal irritation and occasional bleeding.

Naproxen should be used with caution in renal impairment, and use is not recommended in patients whose creatinine clearance is less than 20 mL/min.

Common side effects include heartburn, nausea, dyspepsia, diarrhoea, constipation, gastrointestinal ulceration/bleeding, headache, dizziness, rash, salt and fluid retention, and high blood pressure.

Note: Naproxen poses an intermediate risk of stomach ulcers compared with ibuprofen, which is low-risk, and indomethacin which is high-risk.

Effects on the blood: localized spontaneous bleeding, bruising and prolonged bleeding time have been reported.

It also increases the risk of heart attack, stroke, kidney failure and liver failure.

NSAID can also worsen asthma.

Naproxen may cause muscle cramps in the legs in 3% of people.

Cardiovascular risk

Chronic ibuprofen use has been found correlated with risk of progression to hypertension and myocardial infarction (heart attack). Both the U.S. Food and Drug Administration (FDA) and The European Medicines Agency (EMA) issues warnings of increased heart attack and stroke risk.

Skin

NSAIDs has been associated with the onset of bullous pemphigoid. It can also cause serious skin adverse events such as exfoliative dermatitis, Stevens-Johnson syndrome, and toxic epidermal necrolysis which can be fatal.

Pharmacokinetics

Naproxen and naproxen sodium are readily absorbed from the gastrointestinal tract. Peak plasma concentrations occur about 1 to 2 hours after ingestion of naproxen sodium and about 2 to 4 hours after ingestion of naproxen.

At therapeutic concentrations it is more than 99% bound to plasma proteins.

Diclofenac penetrates synovial fluid; it crosses the placenta and small amounts are distributed into breast milk.

Naproxen has a plasma elimination half-life of about 12 to 17 hours.

It is excreted mainly in the urine (about 95%). Less than 5% of a dose appears in the faeces.