Classifications: analgesic, nonsteroidal antiinflammatory drug (nsaid); antipyretic;
Therapeutic:nsaid, analgesic
; antipyretic
Prototype: Ibuprofen
Pregnancy Category: C


250 mg, 500 mg tablets


A long-acting nonsteroidal antiinflammatory drug (NSAID); unlike aspirin, inhibition of platelet function and effect on bleeding time are dose related and reversible, lasting only about 24 h after drug is discontinued. Is a non-narcotic analgesic agent. Exerts mild antipyretic effect; therefore it is not used clinically for this purpose. This NSAID has peripheral analgesic properties due to interfering with prostaglandin synthesis by inhibiting cyclooxygenase (COX) isoenzymes, COX-1 and COX-2.

Therapeutic Effect

Has analgesic and anti-inflammatory properties.


Acute and long-term relief of mild to moderate pain and symptomatic treatment of osteoarthritis and rheumatoid arthritis.


Patients in whom aspirin or other NSAIDs precipitate an acute asthmatic attack (bronchospasm), urticaria, angioedema, severe rhinitis, or shock; active peptic ulcer, GI bleeding; severe salicylate hypersensitivity. Safe use in children <12 y is not established. Pregnancy (category C); use during third trimester of pregnancy specifically contraindicated because NSAIDs are known to cause premature closure of ductus arteriosus in fetus.

Cautious Use

History of upper GI disease; preexisting renal disease; impaired renal or hepatic function; alcoholics; compromised cardiac function, and other conditions associated with fluid retention; patients receiving diuretics; bone marrow suppression; geriatric patients; hypertension; patients who may be adversely affected by prolonged bleeding time; lactation.

Route & Dosage

Pain Relief
Adult: PO 1000 mg followed by 500 mg q8–12h

Adult: PO 500–1000 mg/d in 2 divided doses (max: 1500 mg/d)


  • Give with water, milk, or food to reduce GI irritation. Food causes slight reduction in absorption rate, but does not affect total amount absorbed.
  • Store at 15°–30° C (59°–86° F) in tightly closed containers unless otherwise directed.

Adverse Effects (≥1%)

Body as a Whole: Hypersensitivity syndrome (fever, chills, rash, eosinophilia, changes in renal and hepatic function, anaphylactic reactions with bronchospasm). CNS: Headache, drowsiness, insomnia, dizziness, vertigo, light-headedness, fatigue, weakness, nervousness, confusion, disorientation. CV: Palpitation, tachycardia, peripheral edema. Special Senses: Tinnitus, hearing loss; blurred vision, reduced visual acuity, changes in color vision, scotomas, corneal deposits, retinal disturbances. GI: Nausea, GI pain, flatulence, GI bleeding, peptic ulcer, anorexia, eructation, cholestatic jaundice. Urogenital: Hematuria, proteinuria, interstitial nephritis, renal failure. Hematologic: Prolonged PT, anemia, decreased serum uric acid, transient elevations of liver function tests. Skin: Rash, toxic epidermal necrolysis, exfoliative dermatitis, urticaria. Other: Weight gain, hyperventilation, dyspnea, photosensitivity.

Diagnostic Test Interference

Diflunisal can lower serum uric acid concentrations by as much as 1.4 mg/dL and increased renal clearance of uric acid.


Drug: antacids decrease diflunisal absorption; aspirin and other nsaids increase risk of GI bleeding; increases risk of warfarin-induced hypoprothrombinemia; increases methotrexate levels and toxicity.


Absorption: Readily from GI tract. Onset: 1 h. Peak: 2–3 h. Duration: 12 h. Distribution: Probably crosses placenta; distributed into breast milk. Metabolism: In liver. Elimination: In urine. Half-Life: 8–12 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor for therapeutic effectiveness: Full antiinflammatory effect for arthritis may not occur until 8 d to several weeks into therapy.
  • Discontinue if patient presents signs of hepatic toxicity (see Appendix F).
  • Note: Although the antipyretic effect is mild, chronic or high doses may mask fever in some patients.

Patient & Family Education

  • Swallow tablet whole; do not crush or chew.
  • Take drug as prescribed. Doubling the dosage can produce greater than doubling of drug accumulation, particularly in patients receiving repetitive doses.
  • Report onset of visual or auditory problems immediately to physician.
  • Be aware of I&O ratio and pattern and check for and report peripheral edema and unusual weight gain.
  • Report promptly to physician the onset of melena, hematemesis, or severe stomach pain.
  • Do not drive or engage in other potentially hazardous activities until reaction to drug is known.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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