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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term treatment of mild to moderate pain.
## Primary Indications
* Pain associated with osteoarthritis and rheumatoid arthritis.
* Menstrual pain (primary dysmenorrhea).
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Do not exceed 1500 mg in the first 24 hours, and do not exceed 1000 mg for any single dose.
* **Primary Dysmenorrhea:** 500 mg every 6 hours, starting at the onset of bleeding and associated pain. Treatment should not exceed 3 days.
## Pediatric Dosing
Mefenamic acid is not generally recommended for use in children under 14 years of age due to lack of established safety and efficacy.
## 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
* 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.
## Adverse Effects
Common adverse effects include diarrhea, nausea, vomiting, abdominal pain, constipation, dizziness, and rash. Serious adverse effects include gastrointestinal bleeding, ulceration, perforation, cardiovascular thrombotic events, renal failure, hepatic failure, and hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **SSRIs and SNRIs:** Increased risk of GI bleeding.
* **ACE inhibitors, ARBs, beta-blockers:** Reduced antihypertensive effect; increased risk of renal impairment.
* **Diuretics:** Reduced diuretic effect; increased risk of renal impairment.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* Monitor renal function, especially in patients with pre-existing renal disease or those taking concomitant nephrotoxic agents.
* Monitor blood pressure.
* Assess for signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid is generally indicated for short-term use.
* Should be taken with food or milk to minimize GI upset.
* Diarrhea is a common and sometimes dose-limiting side effect.
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**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and your healthcare provider for any questions regarding medication use.
