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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.
## Primary Indications
* Management of mild to moderate pain.
* Treatment of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 4 to 6 hours as needed. Do not exceed 4000 mg per day.
* **Dysmenorrhea:** 500 mg every 4 to 6 hours as needed, typically initiated at the onset of pain and bleeding. Do not exceed 4000 mg per day.
## Pediatric Dosing
Mefenamic acid is generally **not recommended** for use in children under 14 years of age due to limited data and potential safety concerns.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dosage reduction may be necessary in severe impairment.
* **Hepatic Impairment:** Use with caution. Dosage reduction may be necessary in severe impairment.
## 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.
* Renal or hepatic failure.
## Adverse Effects
Common adverse effects include diarrhea, nausea, vomiting, abdominal pain, constipation, and dyspepsia. Serious adverse effects can include gastrointestinal bleeding, ulceration, perforation, cardiovascular thrombotic events, myocardial infarction, stroke, renal papillary necrosis, interstitial nephritis, hepatic failure, and severe skin reactions (e.g., Stevens-Johnson syndrome, toxic epidermal necrolysis).
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal adverse effects.
* **Aspirin:** May decrease the cardioprotective effects of low-dose aspirin and increase gastrointestinal bleeding risk.
* **Diuretics:** Reduced diuretic effect and increased risk of renal toxicity.
* **Lithium:** Increased lithium levels and risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* **Renal function:** Monitor BUN and creatinine, especially in elderly patients or those with pre-existing renal disease.
* **Hepatic function:** Monitor liver enzymes, especially with long-term use or in patients with liver disease.
* **Gastrointestinal symptoms:** Assess for signs of bleeding or ulceration.
* **Blood pressure:** NSAIDs can elevate blood pressure.
* **Signs of hypersensitivity reactions.**
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Due to its potential for gastrointestinal toxicity, it is generally recommended for short-term use.
* Concurrent use with other NSAIDs or aspirin should be avoided unless specifically indicated and monitored.
* Discontinue use if diarrhea is persistent or severe.
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*Disclaimer: This information is intended for clinical use and does not substitute for professional medical advice. Always refer to the most current prescribing information and consult with a healthcare professional before making any treatment decisions.*
