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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 inhibition of cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Mild to moderate pain, particularly associated with dysmenorrhea.
* Rheumatoid arthritis (RA) and osteoarthritis (OA).
## Adult Dosing
* **Pain/Dysmenorrhea:** 500 mg every 4-6 hours as needed.
* **RA/OA:** 500 mg three times daily.
* **Maximum Daily Dose:** 1500 mg.
## Pediatric Dosing
* **Pain/Dysmenorrhea:** Not established for children under 14 years.
* **RA:** Not established for children.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment.
* **Hepatic Impairment:** Use with caution.
## Contraindications
* 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).
* Severe renal or hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, constipation, dyspepsia, flatulence.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal failure; hepatic failure; hypersensitivity reactions; exacerbation of asthma; Stevens-Johnson syndrome/toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Other NSAIDs/Aspirin:** Increased risk of gastrointestinal toxicity and bleeding.
* **ACE Inhibitors/ARBs:** Reduced antihypertensive effect, increased risk of renal impairment.
* **Diuretics:** Reduced diuretic effect, increased risk of renal impairment.
* **Lithium:** Increased serum lithium levels, risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* **Baseline and periodic renal function tests (serum creatinine, BUN).**
* **Baseline and periodic liver function tests (ALT, AST).**
* **Monitor for signs and symptoms of gastrointestinal bleeding.**
* **Monitor for signs and symptoms of cardiovascular events.**
* **Monitor for signs and symptoms of hypersensitivity reactions.**
## Clinical Pearls
* Mefenamic acid should be used for the shortest duration necessary to control symptoms.
* Administer with food or milk to minimize gastrointestinal upset.
* Diarrhea is a particularly common and dose-limiting side effect.
* Avoid concurrent use with other NSAIDs.
* Use cautiously in elderly patients, who are at higher risk for adverse events.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making treatment decisions.*
