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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 and for dysmenorrhea.
## Primary Indications
* Mild to moderate pain (e.g., dental pain, musculoskeletal pain)
* Dysmenorrhea
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed.
* **Dysmenorrhea:** 500 mg orally every 6 hours as needed, typically starting with the onset of pain or bleeding and continuing for no more than 6 days per menstrual cycle.
* **Maximum dose:** 1500 mg per day (for general pain) or 1000 mg on the first day and then 500 mg every 6 hours thereafter (for dysmenorrhea) for a maximum of 6 days. Long-term use is not recommended.
## Pediatric Dosing
* Mefenamic acid is generally **not recommended for use in children under 14 years of age** due to limited data and potential risks. Some sources may suggest dosing for children 6 months and older, but this should be done with extreme caution and under strict medical supervision. Specific dosing varies by indication and weight, and is often calculated as 5-7 mg/kg per dose every 6-8 hours.
## Dose Adjustments
* **Renal impairment:** Use with caution. Dose reduction may be necessary in severe renal impairment.
* **Hepatic impairment:** Use with caution. Dose reduction may be necessary in severe hepatic impairment.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, 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.
* Severe heart failure, renal impairment, or hepatic impairment.
* Pregnancy (third trimester).
## Adverse Effects
Common: Nausea, vomiting, diarrhea, abdominal pain, constipation, dizziness, headache.
Serious: Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal failure; hepatic failure; hypersensitivity reactions; Stevens-Johnson syndrome; toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of bleeding.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
* **Other NSAIDs or salicylates:** Increased risk of adverse effects.
* **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect and increased risk of renal impairment.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor for signs and symptoms of cardiovascular events.
* Monitor renal function and liver function tests, especially with prolonged use or in patients with pre-existing impairment.
* Monitor blood pressure.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Use for the shortest duration necessary to control symptoms.
* Avoid concomitant use with other NSAIDs.
* Consider risks versus benefits in elderly patients or those with cardiovascular, renal, or hepatic disease.
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*Disclaimer: This information is intended for educational purposes and does not substitute for professional medical advice. Always consult with a qualified healthcare provider to determine the best course of treatment for your specific condition. Please verify the current prescribing information before making any decisions regarding medication.*
