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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) of the fenamate class. It possesses analgesic, anti-inflammatory, and antipyretic properties through inhibition of cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain, including menstrual pain (dysmenorrhea).
* Management of pain associated with osteoarthritis and rheumatoid arthritis.
## Adult Dosing
* **Pain:** 500 mg every 4 to 6 hours as needed. Maximum daily dose is 1500 mg.
* **Dysmenorrhea:** 500 mg every 4 to 6 hours as needed. Maximum daily dose is 1500 mg.
* **Osteoarthritis/Rheumatoid Arthritis:** 500 mg every 4 to 6 hours. For some patients, 750 mg every 4 to 6 hours may be necessary, but the total daily dose should not exceed 1500 mg.
Treatment duration should be as short as possible and limited to symptomatic relief.
## Pediatric Dosing
Mefenamic acid is **not recommended** for use in children under 14 years of age due to concerns about potential gastrointestinal toxicity and lack of established efficacy and safety data.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Data is limited, but dose reduction may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. Data is limited, but dose reduction may be considered in severe impairment.
* **Elderly:** Consider using the lowest effective dose due to increased risk of adverse events.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, 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.
* Active gastrointestinal bleeding or ulceration.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, headache, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation, myocardial infarction, stroke, renal failure, hepatic failure, anaphylaxis, Stevens-Johnson syndrome, toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Other NSAIDs and Salicylates:** Increased risk of adverse effects, particularly gastrointestinal toxicity.
* **Diuretics and Antihypertensives:** May decrease antihypertensive effect and increase risk of renal toxicity.
* **Lithium and Methotrexate:** May increase serum levels and toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor for signs of cardiovascular events (e.g., chest pain, shortness of breath).
* Monitor renal and hepatic function, especially in patients with pre-existing impairment or those on long-term therapy.
* Monitor blood pressure.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Use for the shortest duration necessary due to the risk of serious gastrointestinal and cardiovascular events.
* Avoid concurrent use with other NSAIDs.
* Consider alternatives if patients have a history of peptic ulcer disease or GI bleeding.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols before making clinical decisions.*
