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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.


A trademark for the drug nabumetone.
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.
Relafen generated sales of pounds 23m for the company in 2002, down from pounds 156m the year before.
We feel that this settlement is a big victory for consumers of Relafen," said Sobol.
Class members' portion of the settlement will be determined based on the state in which Relafen or its generic alternative was purchased.
Similar actions from other plaintiffs in the Relafen antitrust matter, including claims made by Teva, chain drug stores and Eon Labs have also been settled, resulting in further payments from GSK.
Three distributors of generic pharmaceutical products have filed ANDAs for nabumetone, the active ingredient in Relafen, accompanied in each case with a certification of patent invalidity.
Product Therapeutic Category 1998 Sales pounds million $ million Seroxat/Paxil CNS 1,060 1,760 Augmentin Anti-infectives 964 1,600 Zantac Alimentary & Metabolic 757 1,257 Imigran/Imitrex CNS 698 1,159 Flixotide/Flovent Respiratory 498 827 Serevent Respiratory 498 827 Zinnat/Ceftin Anti-infectives 411 682 Zovirax Anti-infectives 403 669 Zofran Alimentary & Metabolic 389 646 Ventolin Respiratory 380 631 Epivir Anti-infectives 359 596 Engerix B Vaccine 346 574 Aquafresh Oral Healthcare 329 546 Becotide Respiratory 309 513 Wellbutrin CNS 307 510 Relafen Musculo-skeletal 307 510 Nicorette/Nicoderm OTC 299 496 Flixonase/Flonase Respiratory 273 453 Combivir Anti-infectives 267 443 8,854 14,699 Source: 1998 Annual Reports and Accounts
Other drugs covered by the bill that would continue to be sold free of price-dropping competition are: Cardiogen-82 (radiologic imaging), Daypro (arthritis), Dermatop (skin ailments), Eulexin (prostate cancer), Nimotop (stroke), Penetrex (urinary tract infections) and Relafen (arthritis).