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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) of the fenamate class. It works by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain in adults and children 12 years and older.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Maximum dose: 1500 mg daily.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, starting with the onset of pain or bleeding, whichever occurs first. Maximum dose: 1500 mg daily.
## Pediatric Dosing
* **Pain and Dysmenorrhea (12 years and older):** 500 mg every 6 hours as needed. Maximum dose: 1500 mg daily.
* **Dosing for children younger than 12 years is not established.**
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe impairment.
## 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.
* Active peptic ulceration or history of recurrent gastrointestinal (GI) bleeding.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, constipation, dyspepsia, dizziness, headache.
* **Serious:** GI bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal failure; hepatic failure; anaphylaxis; Stevens-Johnson syndrome; toxic epidermal necrolysis; exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **ACE inhibitors, ARBs, beta-blockers:** Reduced antihypertensive effect; increased risk of renal dysfunction.
* **Diuretics:** Reduced diuretic effect; increased risk of renal dysfunction.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* **GI symptoms:** Assess for signs and symptoms of bleeding or ulceration.
* **Renal function:** Monitor BUN, creatinine, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic function:** Monitor LFTs if signs of hepatic dysfunction occur.
* **Blood pressure:** Monitor for potential increases.
## Clinical Pearls
* Mefenamic acid is generally recommended for short-term use only due to the risk of GI and cardiovascular adverse effects.
* Advise patients to take with food or milk to minimize GI upset.
* Discontinue immediately if signs of GI bleeding (e.g., black, tarry stools, hematemesis) or hypersensitivity reaction occur.
* Ensure adequate hydration to minimize renal risk.
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*This information is for educational purposes only and does not substitute for professional medical advice. Always consult a qualified healthcare provider for diagnosis and treatment. Confirm current prescribing information with the manufacturer's package insert or other reliable sources before making any treatment decisions.*
