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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for short-term management of mild to moderate pain. It is a weak acid with analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Pain associated with osteoarthritis and rheumatoid arthritis
* Primary dysmenorrhea
* Mild to moderate pain
## Adult Dosing
* **Initial dose:** 500 mg every 4-6 hours as needed.
* **Maximum daily dose:** 1500 mg.
* Treatment should not exceed 7 days.
## Pediatric Dosing
Mefenamic acid is **not recommended** for children under 14 years of age due to limited safety and efficacy data.
## Dose Adjustments
No dose adjustments are typically required for renal or hepatic impairment, but caution is advised. Use in elderly patients may require lower doses and increased monitoring due to potential for increased adverse effects.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* 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.
* Severe renal or hepatic impairment.
* Active peptic ulceration or gastrointestinal bleeding.
* Pregnancy in the third trimester.
## Adverse Effects
Common adverse effects include diarrhea, nausea, vomiting, abdominal pain, constipation, and dizziness. Serious adverse effects can include gastrointestinal bleeding, ulceration, perforation, cardiovascular events (myocardial infarction, stroke), renal toxicity, hepatotoxicity, and hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Other NSAIDs and Salicylates:** Increased risk of adverse effects, including gastrointestinal bleeding.
* **ACE inhibitors, ARBs, beta-blockers:** Decreased antihypertensive effect, increased risk of renal impairment.
* **Diuretics:** Decreased diuretic effect, increased risk of renal impairment.
* **Lithium, Methotrexate:** Increased serum levels and toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor renal function (BUN, creatinine) and hepatic function (LFTs), especially in patients with pre-existing conditions or those on long-term therapy.
* Monitor blood pressure.
* Assess for signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Due to the risk of diarrhea, it is generally recommended for short-term use only (up to 7 days).
* It is less commonly used than other NSAIDs due to its side effect profile, particularly diarrhea.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant guidelines for complete details. Individual patient circumstances may require different management.*
