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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for short-term management of mild to moderate pain.
## Primary Indications
* Pain associated with dysmenorrhea
* Mild to moderate pain (e.g., headache, dental pain, musculoskeletal pain)
## Adult Dosing
* **Pain/Dysmenorrhea:** 500 mg orally every 6 hours as needed. Do not exceed 7 days of use for pain. For dysmenorrhea, treatment should not exceed 6 days.
* **Maximum Dose:** 1500 mg daily.
## Pediatric Dosing
* **Children 12 years and older:** Dosing is the same as adults: 500 mg orally every 6 hours as needed.
* **Children younger than 12 years:** Safety and efficacy have not been established.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Mefenamic acid is primarily eliminated by the kidneys. Patients with severe renal impairment should not use this drug.
* **Hepatic Impairment:** Use with caution. Consider dose reduction in patients with severe hepatic impairment.
## Contraindications
* Hypersensitivity to mefenamic acid 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.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events; renal failure; hepatic failure; hypersensitivity reactions (including Stevens-Johnson syndrome and toxic epidermal necrolysis); bronchospasm; fluid retention and edema; hypertension.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **ACE inhibitors, ARBs, Beta-blockers:** Reduced antihypertensive efficacy; increased risk of renal impairment.
* **Diuretics:** Reduced diuretic efficacy; increased risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* **GI Symptoms:** Monitor for signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* **Renal Function:** Monitor BUN and creatinine, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic Function:** Monitor liver enzymes, especially in patients with hepatic impairment or those receiving long-term therapy.
* **Blood Pressure:** Monitor blood pressure, particularly in patients with hypertension.
## Clinical Pearls
* Due to its potential for GI toxicity, use the lowest effective dose for the shortest duration necessary.
* Mefenamic acid should be taken with food or milk to minimize GI upset.
* Avoid concomitant use with other NSAIDs to reduce the risk of additive toxicity.
* Due to the risk of aseptic meningitis, particularly in patients with autoimmune disorders (e.g., SLE), discontinue if symptoms occur.
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*Disclaimer: This information is intended for clinical use and does not replace full prescribing information. Always verify current prescribing information with the official product labeling and relevant guidelines.*
