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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) from the fenamate class. It is used for the short-term relief of mild to moderate pain.
## Primary Indications
* Primary dysmenorrhea
* Mild to moderate pain, including pain associated with osteoarthritis, rheumatoid arthritis, and dental pain.
## Adult Dosing
* **Dysmenorrhea:** 500 mg every 4-6 hours as needed.
* **Other Pain:** 500 mg initially, followed by 250 mg every 4-6 hours as needed.
* **Maximum Dose:** 1500 mg per 24 hours. Dosing duration should not exceed 7 days.
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age due to lack of established efficacy and safety data.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dosage reduction may be necessary in severe impairment.
* **Hepatic Impairment:** Use with caution. Dosage reduction may be necessary in severe impairment.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* History of bronchospasm, asthma, allergic rhinitis, or urticaria precipitated by aspirin or other NSAIDs.
* Inflammatory bowel disease.
* Renal or hepatic failure.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dizziness, drowsiness, headache.
* **Serious:** Gastrointestinal bleeding, perforation, ulceration; renal toxicity (including interstitial nephritis, papillary necrosis, and renal failure); cardiovascular thrombotic events; hypersensitivity reactions; hepatic reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Diuretics:** Decreased diuretic efficacy; increased risk of nephrotoxicity.
* **Lithium:** Increased serum lithium levels and risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
* **Other NSAIDs:** Increased risk of gastrointestinal and renal adverse effects.
## Monitoring
* **Renal function:** Especially in patients with pre-existing renal disease or those on concomitant nephrotoxic agents.
* **Hepatic function:** Especially in patients with pre-existing hepatic disease.
* **Signs and symptoms of GI bleeding:** Melena, hematemesis, abdominal pain.
* **Blood pressure:** NSAIDs can increase blood pressure.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Should be used at the lowest effective dose for the shortest duration necessary to control symptoms.
* Risk of serious cardiovascular thrombotic events, myocardial infarction, and stroke can occur with NSAID use, even without prior CV events.
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**Disclaimer:** This information is intended for healthcare professionals and does not substitute for a comprehensive understanding of the drug. Always consult the most current prescribing information and institutional protocols before making any clinical decisions.
