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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) of the fenamate class.
## Primary Indications
* Short-term management of mild to moderate pain, including menstrual pain (dysmenorrhea).
* Management of pain and inflammation associated with osteoarthritis and rheumatoid arthritis.
## Adult Dosing
* **Pain:** 500 mg every 4-6 hours as needed. Do not exceed 4000 mg per day.
* **Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed.
* **Osteoarthritis/Rheumatoid Arthritis:** 750 mg three times daily.
## Pediatric Dosing
Mefenamic acid is generally not recommended for use in children under 14 years of age for pain. Dosing for juvenile rheumatoid arthritis in patients 14 years and older is the same as adult dosing for rheumatoid arthritis.
## 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.
* Active gastrointestinal bleeding or ulcer disease.
## Adverse Effects
Common adverse effects include: nausea, vomiting, diarrhea, abdominal pain, constipation, dizziness, headache, and rash. Serious adverse effects include: gastrointestinal bleeding and perforation, cardiovascular thrombotic events, myocardial infarction, stroke, renal failure, hepatic failure, and severe skin reactions.
## 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, particularly in the gastrointestinal tract.
* **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 gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor renal and hepatic function, especially in patients with pre-existing impairment or those on long-term therapy.
* Monitor blood pressure, as NSAIDs can increase blood pressure.
* Monitor for signs of hypersensitivity reactions.
## Clinical Pearls
* Shorten duration of use to the lowest effective dose to minimize risk.
* Administer with food or milk to reduce gastrointestinal upset.
* Consider gastroprotective agents (e.g., PPIs) in patients at high risk for GI complications.
* Discontinue if signs of serious cardiovascular or gastrointestinal events occur.
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*This information is for educational purposes only and does not substitute for professional medical advice. Always consult with a qualified healthcare provider to determine the appropriate treatment for your specific condition and to review the most up-to-date prescribing information.*
