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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term relief of mild to moderate pain. It works by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Pain, mild to moderate, including:
* Dysmenorrhea
* Headache
* Dental pain
* Musculoskeletal pain
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Do not exceed 1500 mg in the first 24 hours of treatment, and do not exceed 1000 mg for any single dose. Treatment should not exceed 7 days.
## Pediatric Dosing
* Mefenamic acid is generally **not recommended** for children younger than 14 years of age. Safety and efficacy in this population have not been established.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustments are established, but dose reduction may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. No specific dose adjustments are established.
## 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.
* Active gastrointestinal bleeding or ulceration.
* Severe heart failure.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, headache, dizziness.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal failure; hepatotoxicity; hypersensitivity reactions; Stevens-Johnson syndrome/toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Aspirin:** May reduce the cardioprotective effect of low-dose aspirin; increased risk of GI toxicity.
* **Corticosteroids:** Increased risk of GI toxicity.
* **Diuretics, ACE inhibitors, ARBs:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
* **Other NSAIDs:** Increased risk of adverse effects.
## Monitoring
* **Renal function:** Monitor BUN and creatinine, especially in elderly patients or those with pre-existing renal disease.
* **Hepatic function:** Monitor LFTs, especially in patients with liver disease or those on long-term therapy.
* **Gastrointestinal symptoms:** Assess for signs and symptoms of GI bleeding or ulceration.
* **Blood pressure:** Monitor for increases in blood pressure.
## Clinical Pearls
* Mefenamic acid is typically used for short-term pain management.
* It should be taken with food or milk to minimize gastrointestinal upset.
* Due to the risk of GI bleeding and cardiovascular events, use the lowest effective dose for the shortest duration necessary.
* Discontinue use and seek medical attention if any signs of GI bleeding (black, tarry stools; bloody vomit) or cardiovascular events (chest pain, shortness of breath) occur.
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*Disclaimer: This information is intended for healthcare professionals and does not replace professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines for definitive patient management decisions.*
