Classifications: analgesic, nonsteroidal antiinflammatory drug (nsaid); antipyretic;
Therapeutic: nsaid, analgesic; antipyretic

Prototype: Ibuprofen
Pregnancy Category: C


250 mg tablets


NSAID that inhibits COX-1 and COX-2 enzymes necessary for prostaglandin synthesis. It affects platelet function.

Therapeutic Effect

Analgesic, antiinflammatory, and antipyretic actions.


Short-term relief of mild to moderate pain including primary dysmenorrhea.


Hypersensitivity to drug; GI inflammation, or ulceration. Safety in children <14 y, during pregnancy (category C) is not established.

Cautious Use

History of kidney or liver disease; blood dyscrasias; asthma; cardiac arrhythmias; CHF; edema; diabetes mellitus; SLE; hypersensitivity to aspirin. Long term use increases risk of serious adverse events (see DRUG INTERACTIONS).

Route & Dosage

Mild to Moderate Pain
Adult: PO Loading Dose 500 mg PO Maintenance Dose 250 mg q6h prn


  • Give with meals, food, or milk to minimize GI adverse effects.
  • Do not use drug for a period exceeding 1 wk (manufacturer's warning).

Adverse Effects (≥1%)

CNS: Drowsiness, insomnia, dizziness, nervousness, confusion, headache. GI: Severe diarrhea, ulceration, and bleeding; nausea, vomiting, abdominal cramps, flatus, constipation, hepatic toxicity. Hematologic: Prolonged prothrombin time, severe autoimmune hemolytic anemia (long-term use), leukopenia, eosinophilia, agranulocytosis, thrombocytopenic purpura, megaloblastic anemia, pancytopenia, bone marrow hypoplasia. Urogenital: Nephrotoxicity, dysuria, albuminuria, hematuria, elevation of BUN. Skin: Urticaria, rash, facial edema. Special Senses: Eye irritation, loss of color vision (reversible), blurred vision, ear pain. Body as a Whole: Perspiration. CV: Palpitation. Respiratory: Dyspnea; acute exacerbation of asthma; bronchoconstriction (in patients sensitive to aspirin).

Diagnostic Test Interference

False-positive reactions for urinary bilirubin (using diazo tablet test).


Drug: Mefenamic acid may prolong bleeding time with oral anticoagulants, heparin; may increase lithium toxicity; increases pharmacologic and toxic activity of phenytoin, sulfonylureas, sulfonamides, warfarin because of protein binding displacement. Herbal: Feverfew, garlic, ginger, ginkgo increase bleeding potential.


Absorption: Rapidly and completely from GI tract. Peak: 2–4 h. Duration: 6 h. Distribution: Distributed in breast milk. Metabolism: Partially in liver. Elimination: 50% in urine, 50% in feces. Half-Life: 2 h.

Nursing Implications

Assessment & Drug Effects

  • Assess patients who develop severe diarrhea and vomiting for dehydration and electrolyte imbalance.
  • Lab tests: With long-term therapy (not recommended) obtain periodic complete blood counts, Hct and Hgb, and kidney function tests.

Patient & Family Education

  • Discontinue drug promptly if diarrhea, dark stools, hematemesis, ecchymoses, epistaxis, or rash occur and do not use again. Contact physician.
  • Notify physician if persistent GI discomfort, sore throat, fever, or malaise occur.
  • Do not drive or engage in potentially hazardous activities until response to drug is known. It may cause dizziness and drowsiness.
  • Monitor blood glucose for loss of glycemic control if diabetic.

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

© 2006-2022 Last Updated On: 11/20/2022 (0)
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