Please check your internet connection and try again.
# Mefenamic Acid
## Overview
Mefenamic acid is an anthranilic acid derivative nonsteroidal anti-inflammatory drug (NSAID) that exhibits analgesic, anti-inflammatory, and antipyretic properties via non-selective inhibition of cyclooxygenase (COX-1/COX-2) enzymes.
## Primary Indications
* Management of mild to moderate pain.
* Treatment of primary dysmenorrhea.
* *Note: Treatment duration should not exceed 7 days.*
## Adult Dosing
* **Initial Dose:** 500 mg orally once, followed by 250 mg orally every 6 hours as needed.
* **Maximum Dose:** Do not exceed a total daily dose of 1,000 mg (1 g).
## Pediatric Dosing
* **Patients ≥14 years:** Use adult dosing guidelines.
* **Patients <14 years:** Safety and efficacy have not been established; use is generally discouraged.
## Dose Adjustments
* **Renal Impairment:** Avoid in patients with severe renal impairment (CrCl <30 mL/min). Use with caution in mild-to-moderate impairment; monitor renal function closely.
* **Hepatic Impairment:** Use with caution; monitor for signs of liver toxicity. Dosage reduction may be required.
## Contraindications
* Known hypersensitivity to mefenamic acid or other NSAIDs (including aspirin-induced asthma or urticaria).
* History of GI bleeding or perforation related to previous NSAID therapy.
* Active peptic ulcer disease or inflammatory bowel disease.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Severe renal or hepatic failure.
## Adverse Effects
* **GI:** Nausea, vomiting, diarrhea (frequent), abdominal pain, dyspepsia, risk of GI ulceration/bleeding.
* **CV:** Hypertension, peripheral edema, increased risk of thrombotic events (MI, stroke).
* **Renal:** Acute kidney injury, interstitial nephritis, fluid retention.
* **CNS:** Dizziness, headache, drowsiness.
* **Hematologic:** Potential for transient leukopenia, thrombocytopenia, or anemia.
## Key Drug Interactions
* **Anticoagulants:** Increased risk of bleeding (e.g., warfarin, apixaban).
* **Other NSAIDs/Aspirin:** Increased risk of GI toxicity and additive side effects.
* **ACE Inhibitors/ARBs/Diuretics:** Reduced antihypertensive efficacy and increased risk of acute renal failure.
* **Lithium/Methotrexate:** Decreased renal clearance leads to potential toxicity of these agents.
## Monitoring
* **GI:** Monitor for signs of bleeding (melena, hematemesis).
* **Renal:** Monitor serum creatinine and electrolytes, particularly in elderly or those on diuretics.
* **Blood Pressure:** Monitor periodically during chronic use.
* **Liver:** Monitor LFTs if signs of hepatic insufficiency develop.
## Clinical Pearls
* **Duration Limit:** Due to the risk of significant GI side effects, therapy is strictly limited to 7 days.
* **Administration:** Administer with food or milk to minimize GI irritation.
* **Diarrhea:** Mefenamic acid has a unique propensity to cause dose-related diarrhea; discontinue if this occurs.
* **Cardiovascular Caution:** Like all non-aspirin NSAIDs, it carries a boxed warning regarding cardiovascular thrombotic events.
***
**Educational Disclaimer:** This information is for educational purposes only. Clinical practice protocols and prescribing guidelines may vary by region. Always consult the latest official manufacturer prescribing information (package insert) and institutional formulary guidelines before prescribing or administering any medication.
