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# Mefanamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the anthranilic acid derivatives class. It exhibits analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Mild to moderate pain, including menstrual pain (dysmenorrhea).
* Rheumatoid arthritis and osteoarthritis (less commonly used for chronic conditions due to GI side effect profile).
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Maximum daily dose is 1500 mg.
* **Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed. Maximum daily dose is 1250 mg for this indication.
* Dosing duration should generally be limited to 7 days or less.
## Pediatric Dosing
Mefenamic acid is **not typically recommended for children under 14 years of age** due to lack of established safety and efficacy data in this population.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe impairment.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of bronchospasm, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal bleeding or a history of recurrent gastrointestinal ulceration or bleeding.
* Severe renal or hepatic impairment.
* Severe heart failure.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, dizziness, headache, rash.
* **Serious:** Gastrointestinal bleeding and ulceration, renal toxicity (including interstitial nephritis, papillary necrosis, renal failure), hepatic toxicity (including hepatitis, jaundice), cardiovascular thrombotic events (myocardial infarction, stroke), hypersensitivity reactions (including anaphylaxis, Stevens-Johnson syndrome, toxic epidermal necrolysis), bronchospasm, exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal bleeding and ulceration.
* **Other NSAIDs or Salicylates:** Increased risk of adverse effects, particularly gastrointestinal bleeding.
* **ACE Inhibitors/ARBs/Diuretics:** Reduced antihypertensive effect and increased risk of renal toxicity.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor renal function (serum creatinine, BUN) especially in patients with pre-existing renal disease or those at risk.
* Monitor liver function (ALT, AST, bilirubin) especially in patients with pre-existing liver disease.
* Monitor blood pressure.
* Assess for signs of hypersensitivity reactions.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Use the lowest effective dose for the shortest duration necessary.
* Consider gastroprotective agents (e.g., PPIs) in patients at high risk for GI complications.
* Advise patients to avoid concomitant use of aspirin or other NSAIDs.
* Discontinue use immediately if signs of bleeding, renal dysfunction, or hypersensitivity occur.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information, product monographs, and relevant guidelines before initiating or modifying therapy. Local protocols may dictate specific dosing or management strategies.
