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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.
* **Dysmenorrhea:** 500 mg every 6 hours, initiated at the onset of pain and bleeding, and continued for the duration of dysmenorrhea.
* **Maximum:** Not to exceed 4000 mg per day. Dosing beyond 7 days is not recommended.
## Pediatric Dosing
Mefenamic acid is not generally recommended for use in children under 14 years of age due to limited data on efficacy and safety.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustment is established, but may require dose reduction in severe impairment.
* **Hepatic Impairment:** Use with caution. No specific dose adjustment is established, but may require dose reduction 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.
## Adverse Effects
* **Common:** Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), dyspepsia, constipation, headache, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal injury; hepatic dysfunction; 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.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of bleeding.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased methotrexate levels and toxicity.
* **Other NSAIDs (including aspirin):** Increased risk of adverse effects, particularly gastrointestinal.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding or ulceration.
* Renal function (serum creatinine, BUN).
* Hepatic function (transaminases).
* Blood pressure.
## Clinical Pearls
* Should be taken with food or milk to minimize gastrointestinal upset.
* Duration of use should be limited to the shortest effective period.
* Due to potential for dizziness and drowsiness, caution patients regarding driving or operating machinery.
* Risk of serious cardiovascular thrombotic events, myocardial infarction, and stroke may increase with duration of use, as well as with pre-existing cardiovascular risk factors or disease.
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**Disclaimer:** This information is intended for clinical use and is not a substitute for professional medical advice. Always verify current prescribing information with an official drug monograph or your institution's formulary before making any clinical decisions.
