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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It exhibits analgesic, anti-inflammatory, and antipyretic properties through the inhibition of cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Maximum daily dose: 1500 mg.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, starting with the onset of pain and bleeding and continuing for no more than 3 days.
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age due to limited safety and efficacy data. For specific indications in older children (14 years and older), dosing may mirror adult recommendations, but consultation with pediatric guidelines or specialists is advised.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustment is established, but reduced doses may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. No specific dose adjustment is established, but reduced doses may be considered in severe impairment.
## Contraindications
* Known hypersensitivity to mefenamic acid or other NSAIDs.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease (IBD) (e.g., Crohn's disease, ulcerative colitis).
* Severe heart failure.
## Adverse Effects
Common: Diarrhea, nausea, vomiting, abdominal pain, constipation, dizziness, headache.
Serious: Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events; renal toxicity; hepatic toxicity; hypersensitivity reactions; bronchospasm; Stevens-Johnson syndrome/toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal bleeding and ulceration.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) & Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of gastrointestinal bleeding.
* **Lithium:** Increased serum lithium levels, potential for toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
* **ACE inhibitors, Angiotensin II Receptor Blockers (ARBs), Beta-blockers:** May reduce antihypertensive effect and increase risk of renal impairment.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Renal function (serum creatinine, BUN) particularly in patients with pre-existing renal disease or those on concomitant nephrotoxic agents.
* Liver function tests (ALT, AST) if signs of liver dysfunction develop.
* Blood pressure, especially in patients with hypertension.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Due to the risk of renal toxicity and gastrointestinal bleeding, mefenamic acid should be used for the shortest duration necessary and at the lowest effective dose.
* Discontinue use immediately if signs of hypersensitivity, gastrointestinal bleeding, or renal/hepatic dysfunction occur.
* Not recommended for chronic use.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult current prescribing information, institutional protocols, and patient-specific factors before making any treatment decisions.*
