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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 6 hours as needed. Do not exceed 4000 mg/day.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, typically starting with the onset of pain and bleeding and continuing for the duration of the symptoms.
## Pediatric Dosing
Mefenamic acid is **not typically recommended** for use in pediatric patients for pain or dysmenorrhea due to limited data and potential safety concerns.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustment is established, but dose reduction may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. No specific dose adjustment is established, but dose reduction may be considered in severe impairment.
* **Elderly:** Consider reduced doses and increased monitoring due to potential for increased risk of adverse effects.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of bronchospasm, 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: Diarrhea, nausea, vomiting, abdominal pain, dyspepsia, constipation, headache, dizziness, rash.
Serious: Gastrointestinal bleeding, ulceration, perforation; renal failure; hepatic failure; cardiovascular thrombotic events (MI, stroke); hypersensitivity reactions; Stevens-Johnson syndrome; toxic epidermal necrolysis; exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **ACE inhibitors, ARBs, diuretics:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Lithium:** Increased serum lithium levels and risk of toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
* **Other NSAIDs, aspirin:** Increased risk of adverse effects, particularly gastrointestinal.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Renal function (BUN, creatinine) especially in patients with pre-existing renal disease or those at risk.
* Liver function tests (AST, ALT) if signs of hepatic impairment develop.
* Blood pressure.
* Signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid should be used at the lowest effective dose for the shortest duration necessary.
* Concomitant use with other NSAIDs or aspirin should be avoided unless specifically indicated and monitored closely.
* It is typically taken with food or milk to minimize gastrointestinal upset.
* Patients with a history of gastrointestinal disease should use with caution.
* Discontinue use immediately if signs of serious adverse effects occur.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the official prescribing information and current clinical guidelines for complete details and to ensure patient safety.*
