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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) of the fenamate class used for the short-term treatment of mild to moderate pain. It works by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Pain, including menstrual pain (dysmenorrhea).
* Rheumatoid arthritis and osteoarthritis (less commonly used than other NSAIDs).
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Do not exceed 4000 mg daily. Treatment duration typically should not exceed 7 days.
* **Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed.
## Pediatric Dosing
* **Pain:** Generally not recommended for children younger than 14 years. For children 14 years and older, adult dosing applies. Limited data exists for younger children.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustment is universally recommended, but dose reduction may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. No specific dose adjustment is universally recommended.
## Contraindications
* 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.
* Inflammatory bowel disease.
* Severe renal, hepatic, or cardiac impairment.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation.
* **Serious:** Cardiovascular thrombotic events (MI, stroke), GI bleeding, ulceration, perforation, renal impairment, hepatic dysfunction, hypersensitivity reactions, 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.
* **ACE inhibitors, ARBs, Beta-blockers:** May reduce antihypertensive efficacy and increase risk of renal impairment.
* **Diuretics:** May reduce diuretic efficacy and increase risk of renal impairment.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* Signs and symptoms of GI bleeding and ulceration.
* Renal and hepatic function, especially in patients with pre-existing impairment or those on long-term therapy.
* Blood pressure.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only.
* Consider prescribing a proton pump inhibitor (PPI) for patients at increased risk of GI complications.
* Ensure adequate hydration to minimize the risk of renal adverse effects.
* Advise patients to report any signs of bleeding (e.g., black tarry stools, hematemesis) or severe abdominal pain immediately.
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**Disclaimer:** This information is for educational purposes only and does not substitute for professional medical advice. Always consult with a qualified healthcare provider and verify the most current prescribing information before making any treatment decisions.
