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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It possesses analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 4 to 6 hours as needed.
* **Dysmenorrhea:** 500 mg every 4 to 6 hours as needed, starting with the onset of pain and bleeding.
* **Maximum Dose:** Not to exceed 1500 mg in a 24-hour period. Treatment duration is typically limited to 7 days.
## Pediatric Dosing
* Generally not recommended for children under 14 years of age due to lack of established safety and efficacy data.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Data is limited, but dose reduction may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. Data is limited, but dose reduction may be considered in severe impairment.
## 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.
* Active gastrointestinal bleeding or a history of recurrent gastrointestinal bleeding.
* Severe renal impairment.
* Severe hepatic impairment.
* Severe heart failure.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Abdominal pain, nausea, vomiting, diarrhea, dyspepsia, constipation, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal failure; hepatic failure; hypersensitivity reactions (including anaphylaxis); 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.
* **Other NSAIDs (including aspirin):** Increased risk of adverse effects, particularly gastrointestinal bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of gastrointestinal bleeding.
* **Diuretics and Antihypertensives:** May decrease their efficacy and increase risk of renal damage.
* **Lithium:** Increased serum lithium levels and risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* **Gastrointestinal:** Monitor for signs and symptoms of bleeding, ulceration, and perforation.
* **Renal:** Monitor renal function, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic:** Monitor liver function tests, especially in patients with pre-existing hepatic disease.
* **Cardiovascular:** Assess cardiovascular risk factors.
## Clinical Pearls
* Mefenamic acid is typically recommended for short-term use only.
* Administer with food or milk to minimize gastrointestinal upset.
* Ensure adequate hydration to prevent renal complications.
* Discontinue use immediately if signs of hypersensitivity or serious adverse events occur.
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**Disclaimer:** This information is intended for clinical use and does not substitute for professional medical advice. Always consult the most current prescribing information and product literature, and consider individual patient factors before making any treatment decisions.
