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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
* Mild to moderate pain, particularly associated with:
* Dysmenorrhea
* Headache
* Toothache
* Muscle pain
* Rheumatic pain
* Inflammation associated with musculoskeletal disorders.
## Adult Dosing
* **Pain/Dysmenorrhea:** 500 mg every 6 hours as needed.
* **Maximum Daily Dose:** 1500 mg (three divided doses). A course of treatment typically should not exceed 7 days.
## Pediatric Dosing
Mefenamic acid is not generally recommended for use in children under 14 years of age due to limited safety and efficacy data.
## Dose Adjustments
No specific dose adjustments are routinely required for renal or hepatic impairment, however caution is advised. Patients with severe renal or hepatic impairment should have dosing carefully considered and potentially reduced.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of NSAID-induced bronchospasm, urticaria, or allergic rhinitis.
* Inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis).
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, headache, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal impairment; hepatic impairment; cardiovascular thrombotic events; hypersensitivity reactions; exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of gastrointestinal bleeding.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
* **ACE inhibitors, ARBs, Beta-blockers:** Reduced antihypertensive effect; increased risk of renal impairment.
* **Diuretics:** Reduced diuretic effect; increased risk of renal impairment.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Assess renal function (BUN, creatinine) and liver function (ALT, AST) periodically, especially with prolonged use or in patients with risk factors.
* Monitor blood pressure.
* Assess for signs of hypersensitivity or allergic reaction.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Due to potential dizziness and drowsiness, patients should exercise caution when driving or operating machinery.
* Use the lowest effective dose for the shortest duration necessary to minimize risks.
* Avoid concomitant use with other NSAIDs.
* Risk of serious cardiovascular thrombotic events, myocardial infarction, and stroke may increase with duration of use.
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**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for complete prescribing information. Always consult the most current product information and local protocols before prescribing.
