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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, including menstrual pain (dysmenorrhea).
* Relief of signs and symptoms of rheumatoid arthritis and osteoarthritis.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Rheumatoid Arthritis/Osteoarthritis:** 750 mg every 6 hours as needed, not to exceed 4000 mg/day.
## Pediatric Dosing
Mefenamic acid is generally **not recommended** for pediatric patients under 14 years of age due to limited safety and efficacy data.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment. Data on specific dose adjustments are limited.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe impairment. Data on specific dose adjustments are limited.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Inflammatory bowel disease (Crohn's disease, ulcerative colitis).
* Severe renal or hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include: nausea, vomiting, diarrhea, abdominal pain, constipation, dizziness, headache, rash, and fluid retention. Serious adverse effects include: gastrointestinal bleeding, ulceration, perforation, cardiovascular thrombotic events, myocardial infarction, stroke, renal impairment, hepatic toxicity, and hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Other NSAIDs and Salicylates:** Increased risk of GI toxicity and additive effects.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **ACE inhibitors, ARBs, Beta-blockers:** Reduced antihypertensive efficacy and increased risk of renal dysfunction.
* **Diuretics:** Reduced diuretic efficacy and increased risk of renal dysfunction.
* **Lithium:** Increased lithium levels and risk of toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* Signs and symptoms of GI bleeding or ulceration.
* Renal function (serum creatinine, BUN).
* Hepatic function (ALT, AST).
* Blood pressure.
* Signs and symptoms of cardiovascular events.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize GI upset.
* Duration of treatment should be as short as possible due to the risk of adverse effects.
* Patients with a history of cardiovascular disease or risk factors should use mefenamic acid with caution.
* Avoid concurrent use with other NSAIDs.
* The maximum recommended daily dose should not be exceeded.
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**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant guidelines before making any clinical decisions. Dosing and recommendations may vary based on individual patient factors and local protocols.
