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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) of the anthranilic acid derivative 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 1500 mg in a 24-hour period.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, starting with the onset of bleeding and associated symptoms. Do not exceed 1500 mg in a 24-hour period.
* Treatment should be limited to a maximum of 7 days.
## Pediatric Dosing
The safety and efficacy of mefenamic acid in pediatric patients under 14 years of age have not been established.
## 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, aspirin, or other NSAIDs.
* History of NSAID-induced bronchospasm, asthma, rhinitis, or urticaria.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal (GI) bleeding or ulceration.
* Inflammatory bowel disease.
* Severe heart failure.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, constipation, headache, dizziness, rash.
* **Serious:** GI bleeding, ulceration, and perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal failure; hepatic failure; hypersensitivity reactions; bronchospasm; Stevens-Johnson syndrome/toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI adverse effects.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **ACE inhibitors, ARBs, Beta-blockers:** May decrease antihypertensive effect and increase risk of renal dysfunction.
* **Diuretics:** May decrease diuretic effect and increase risk of renal dysfunction.
* **Lithium:** Increased lithium levels and risk of toxicity.
* **Methotrexate:** Increased methotrexate levels and risk of toxicity.
## Monitoring
* Signs and symptoms of GI bleeding (e.g., melena, hematemesis, abdominal pain).
* Renal function (BUN, creatinine).
* Liver function tests (ALT, AST).
* Blood pressure.
* Signs and symptoms of cardiovascular events.
## Clinical Pearls
* Mefenamic acid is generally recommended for short-term use due to the risk of GI and cardiovascular adverse effects.
* Administer with food or milk to minimize GI upset.
* Diarrhea is a common dose-limiting side effect.
* Consider risks vs. benefits in patients with pre-existing renal disease, heart failure, or hypertension.
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**Disclaimer:** This information is intended for healthcare professionals and should not be considered a substitute for professional medical advice. Always consult the current prescribing information and relevant clinical guidelines for the most up-to-date and comprehensive drug information.
