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Related to Relafen: Norflex


(na-byoo-me-tone) ,


(trade name)


Therapeutic: antirheumatics
Pregnancy Category: C


Symptomatic management of rheumatoid arthritis and osteoarthritis.


Inhibits prostaglandin synthesis.

Therapeutic effects

Suppression of pain and inflammation.


Absorption: Nabumetone (a prodrug) is 80% absorbed after oral administration; 35% is rapidly converted to 6-methoxy-2-naphthylacetic acid (6-MNA), which is the active drug.
Distribution: Unknown.
Protein Binding: >99%.
Metabolism and Excretion: 6-MNA is metabolized by the liver to inactive compounds.
Half-life: 24 hr (increased in severe renal impairment).

Time/action profile (analgesia/anti-inflammatory effects)

PO1–2 daysfew days–2 wk12–24 hr


Contraindicated in: Hypersensitivity;Use with other NSAIDs, including aspirin; cross-sensitivity may occur;Active GI bleeding or ulcer disease;Peri-operative pain from coronary artery bypass graft (CABG) surgery; Lactation: Lactation.
Use Cautiously in: Severe renal, or hepatic disease;History of ulcer disease; Obstetric: Avoid using during 2nd half of pregnancy due to potential of NSAIDs to cause premature closure of ductus arteriosus; Pediatric: Safety not established.

Adverse Reactions/Side Effects

Central nervous system

  • agitation
  • anxiety
  • confusion
  • depression
  • dizziness
  • drowsiness
  • fatigue
  • headache
  • insomnia
  • malaise
  • weakness

Ear, Eye, Nose, Throat

  • abnormal vision
  • tinnitus


  • dyspnea
  • hypersensitivity pneumonitis


  • edema
  • fluid retention
  • vasculitis


  • gi bleeding (life-threatening)
  • abdominal pain (most frequent)
  • diarrhea (most frequent)
  • ↑ liver function tests
  • anorexia
  • constipation
  • dry mouth
  • dyspepsia
  • flatulence
  • gastritis
  • gastroenteritis
  • ↑ appetite
  • nausea
  • stomatitis
  • vomiting


  • albuminuria
  • azotemia
  • interstitial nephritis


  • exfoliative dermatitis (life-threatening)
  • stevens-johnson syndrome (life-threatening)
  • toxic epidermal necrolysis (life-threatening)
  • increased sweating
  • photosensitivity
  • pruritus
  • rash


  • prolonged bleeding time


  • weight gain


  • paresthesia
  • tremor


  • allergic reactions including anaphylaxis (life-threatening)
  • angioneurotic edema (life-threatening)


Drug-Drug interaction

↑ adverse GI effects with aspirin, other NSAIDs, potassium supplements, corticosteroids, or alcohol.Chronic use with acetaminophen may ↑ risk of adverse renal reactions.May ↓ effectiveness of diuretics or antihypertensives.May ↑ hypoglycemic effects of insulins or oral hypoglycemic agents.↑ risk of toxicity from methotrexate.↑ risk of bleeding with cefotetan, cefoperazone, valproic acid, anticoagulants, ticlopidine, clopidogrel, eptifibatide, tirofiban, or thrombolytic agents.↑ risk of adverse hematologic reactions with antineoplastics or radiation therapy.Concurrent use with cyclosporine may ↑ risk of renal toxicity.


Oral (Adults) 1000 mg/day as a single dose or divided dose twice daily; may be ↑ up to 2000 mg/day; use lowest effective dose during chronic therapy.

Availability (generic available)

Tablets: 500 mg, 750 mg

Nursing implications

Nursing assessment

  • Patients who have asthma, aspirin-induced allergy, and nasal polyps are at increased risk for developing hypersensitivity reactions. Monitor for rhinitis, asthma, and urticaria.
  • Assess pain and range of motion before and periodically throughout therapy.
  • Lab Test Considerations: Evaluate BUN, serum creatinine, CBC, and liver function periodically in patients receiving prolonged therapy.
    • Serum potassium, BUN, serum creatinine, alkaline phosphatase, LDH, AST, and ALT tests may show ↑ levels. Blood glucose, hemoglobin, and hematocrit concentrations, leukocyte and platelet counts, and CCr may be ↓.
    • May cause prolonged bleeding time.

Potential Nursing Diagnoses

Acute pain (Indications)
Impaired physical mobility (Indications)


  • Administration in higher than recommended doses does not provide increased effectiveness but may cause increased side effects. Use lowest effective dose for the shortest duration possible to minimize cardiac risks.
  • Oral: Administer with meals or antacids to decrease GI irritation and increase absorption.

Patient/Family Teaching

  • Advise patient to take this medication with a full glass of water and to remain in an upright position for 15–30 min after administration.
  • Instruct patient to take medication as directed. Take missed doses as soon as remembered but not if almost time for the next dose. Do not double dose.
  • May cause drowsiness, dizziness, or visual disturbances. Advise patient to avoid driving or other activities requiring alertness until response to the medication is known.
  • Advise patient to use sunscreen and protective clothing to prevent photosensitivity reactions.
  • Caution patient to avoid the concurrent use of alcohol, aspirin, acetaminophen, or other OTC medications without consulting health care professional.
  • Advise patient to inform health care professional of medication regimen before treatment or surgery.
  • Advise patient to consult health care professional if rash, itching, visual disturbances, tinnitus, weight gain, edema, black stools, persistent headache, or influenza-like syndrome (chills, fever, muscle aches, pain) occurs.

Evaluation/Desired Outcomes

  • Decreased pain and improved joint mobility. Partial arthritic relief is usually seen within 1 wk, but maximum effectiveness may require 2 wk or more of continuous therapy. Patients who do not respond to one NSAID may respond to another.
Drug Guide, © 2015 Farlex and Partners


A trademark for the drug nabumetone.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
References in periodicals archive ?
"GSK continues to believe that its actions were appropriate in obtaining and enforcing its patent for Relafen," the company said in a statement.
when it upheld a 2001 ruling that invalidated GSK's patent for nabumetone, the active ingredient in Relafen. The drug recorded about $239 million in sales last year.
Glaxo SmithKline fell 37p to pounds 19.10 after dealers dumped the stock when the group lost a court case to protect its US patent on Relafen, an arthritis drug.
As for pharmaceuticals, there's, been ad growth due to the promotion of products such as Flonase, Tagament and Relafen.
Another patent dispute that could be decided next year involves SmithKline Beecham PLC's Relafen, a drug that several generic companies hope to launch.
for urinary tract infections) and Relafen (from SmithKline Beecham Pharmaceuticals for arthritis).
The other potential candidates for patent extensions are ScheringPlough's cancer drug Eulexin; Bayer Corp.'s calcium channel blocker Nimotop; SmithKline Beecham PLC's nonsteroidal anti-inflammatory medication (NSAID) Relafen; Dermatop, Ortho Dermatological's corticosteroid emollient cream; RhonePouleneu Rorer Pharmaceuticals Inc.'s antibacterial drug Penetrex; Braccol Diagnostics' diagnostic agent Cardiogen-82; and G.D.
Drugs that would have realized major financial gains from the amendment were Claritin and Eulex-in, both made by Schering-Plough Corp.; SmithKline Beecham PLC'S Relafen; Cardiogen 82, made by Bristol-Myers Squibb Co.; Dermatop.
(Last year SmithKline was cited for Relafen, an arthritis medication.) Paxil, which is a potent and highly selective serotonin inhibitor, has been indicated for long-term treatment of depression and prevention of relapse.
Its recent new drug releases include Relafen, an anti-arthritis compound; Seroxat, an antidepressant; Kytril, an antinausea agent; Havrix, the world's first hepatitis A vaccine; and Paxil, a Prozac-like drug for depression.
Additionally, American Home Products Corp.'s Ismo (an analgesic for chest pains), Merck & Co.'s Zocor (a cholesterol-lowering treatment) and SmithKline Beecham PLC's Relafen arthritis treatment were given the go-ahead.