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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the anthranilic acid derivative class. It exhibits analgesic, anti-inflammatory, and antipyretic properties through the inhibition of cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Treatment should not exceed 7 days.
* **Dysmenorrhea:** 500 mg every 6 hours starting with the onset of pain and bleeding, and continuing for the duration of the symptoms, up to 7 days.
The maximum recommended daily dose is 1500 mg.
## Pediatric Dosing
Mefenamic acid is generally **not recommended** for use in children under 14 years of age due to a lack of established safety and efficacy data.
## Dose Adjustments
No specific dose adjustments are typically required for hepatic or renal impairment, however, caution is advised due to potential for NSAID-induced organ damage. Mefenamic acid should be used with caution and at the lowest effective dose in elderly patients.
## 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.
* Active gastrointestinal bleeding or ulceration.
## Adverse Effects
* **Common:** Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), dizziness, headache.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal toxicity; hepatic toxicity; hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Other NSAIDs or salicylates:** Increased risk of adverse effects, including gastrointestinal toxicity.
* **Diuretics, ACE inhibitors, ARBs:** May reduce antihypertensive effect and increase risk of renal toxicity.
* **Lithium:** Increased lithium levels and risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Assess for signs of cardiovascular events.
* Monitor renal and hepatic function, especially with prolonged use or in patients with pre-existing organ impairment.
* Monitor for signs of hypersensitivity.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Due to its short half-life and risk of gastrointestinal side effects, mefenamic acid is typically recommended for short-term use only.
* It is essential to use the lowest effective dose for the shortest duration necessary to minimize risks.
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*This information is intended for clinical decision support and does not replace the need to consult the most current prescribing information and institutional protocols.*
