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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term management of mild to moderate pain.
## Primary Indications
* Pain associated with osteoarthritis and rheumatoid arthritis.
* Menstrual pain (dysmenorrhea).
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Maximum dose is 1500 mg per day.
* **Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed. Maximum dose is 1250 mg per day.
* **Duration:** Typically for short-term use.
## Pediatric Dosing
* **General Pain/Dysmenorrhea:** Dosing is not well-established for children under 14 years of age. Use is generally not recommended in this age group. For patients 14 years and older, adult dosing may be considered.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary; however, specific guidelines are not well-defined. Monitor renal function closely.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary; however, specific guidelines are not well-defined. Monitor hepatic function closely.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of bronchospasm, asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease.
* Severe heart failure.
* Severe renal impairment.
* Severe hepatic impairment.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, headache, dizziness.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal failure; hepatic failure; hypersensitivity reactions; exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Aspirin:** May decrease the cardioprotective effect of low-dose aspirin and increase the risk of gastrointestinal adverse effects.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Diuretics:** Reduced diuretic efficacy and increased risk of nephrotoxicity.
* **Lithium:** Increased lithium levels and risk of toxicity.
* **Methotrexate:** Increased methotrexate levels and risk of toxicity.
## Monitoring
* **Renal function:** Serum creatinine, BUN, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic function:** Liver enzymes (ALT, AST), especially in patients with pre-existing hepatic disease or those at risk.
* **Gastrointestinal symptoms:** Monitor for signs of bleeding (melena, hematemesis) or ulceration.
* **Blood pressure:** NSAIDs can cause or worsen hypertension.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only.
* Administer with food or milk to reduce gastrointestinal upset.
* Patients with a history of GI bleeding or ulceration should use this medication with extreme caution or avoid it.
* Consider the risk of cardiovascular and renal adverse events, particularly with prolonged use or in high-risk patients.
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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 literature for complete details before making any treatment decisions. Dosing and recommendations may vary based on individual patient factors and local protocols.
