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# Mefenamic Acid
## Overview
Mefenamic acid is a non-steroidal 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.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain/Dysmenorrhea:** 500 mg every 6 to 8 hours as needed. Do not exceed 4000 mg daily. Treatment should not exceed 7 days.
## Pediatric Dosing
* **Age 14 years and older:** Dosing is the same as adults.
* **Younger than 14 years:** Mefenamic acid is generally not recommended due to limited data and potential for toxicity. Safety and efficacy have not been established.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Data is limited, but dose reduction may be necessary in severe impairment.
* **Hepatic Impairment:** Use with caution. Data is limited, but dose reduction may be necessary in severe impairment.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* 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.
* Active gastrointestinal (GI) bleeding or history of GI bleeding/ulceration with previous NSAID use.
* Severe heart failure, renal impairment, or hepatic impairment.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, headache, dizziness.
* **Serious:**
* **Cardiovascular:** Increased risk of myocardial infarction, stroke, and heart failure.
* **Gastrointestinal:** GI bleeding, ulceration, perforation.
* **Renal:** Renal impairment, interstitial nephritis, papillary necrosis.
* **Hepatic:** Hepatotoxicity, elevated liver enzymes.
* **Hematologic:** Anemia, leukopenia, thrombocytopenia.
* **Hypersensitivity:** Anaphylaxis, Stevens-Johnson syndrome, toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Other NSAIDs and Aspirin:** Increased risk of GI toxicity and other adverse effects.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **ACE inhibitors, ARBs, Beta-blockers:** Reduced antihypertensive effect; increased risk of renal impairment.
* **Diuretics:** Reduced diuretic effect; increased risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* **Renal function:** Especially in patients with pre-existing renal disease or those at risk.
* **Liver function:** Especially in patients with pre-existing hepatic disease or those at risk.
* **Hemoglobin/Hematocrit:** For signs of GI bleeding or anemia.
* **Signs and symptoms of GI bleeding:** Black tarry stools, hematemesis, abdominal pain.
* **Blood pressure:** NSAIDs can increase blood pressure.
## Clinical Pearls
* Mefenamic acid is typically used for short-term pain management.
* The risk of serious GI and cardiovascular events increases with dose and duration of use.
* It is generally recommended to use the lowest effective dose for the shortest duration necessary.
* Administer with food or milk to minimize GI upset.
* Avoid use in patients with active peptic ulcer disease or a history of NSAID-induced ulcers.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making treatment decisions. Dosing and indications may vary based on local protocols and individual patient factors.*
