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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) with analgesic, anti-inflammatory, and antipyretic properties. It acts by inhibiting the cyclooxygenase (COX-1 and COX-2) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Mild to moderate pain.
* Primary dysmenorrhea.
* Symptomatic relief of fever (in pediatric formulations).
## Adult Dosing
* **Pain/Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed.
* **Duration:** Therapy should not exceed 7 days to minimize gastrointestinal and renal toxicity.
## Pediatric Dosing
*Note: Use is generally limited to children >6 months or >1 year depending on specific brand formulation (e.g., Meftal-P).*
* **Fever/Pain:** 6.5 mg/kg per dose, administered every 6 to 8 hours as needed.
* **Maximum Daily Dose:** Do not exceed 4 doses in a 24-hour period.
## Dose Adjustments
* **Renal Impairment:** Avoid or use with extreme caution in patients with severe renal impairment (CrCl <30 mL/min).
* **Hepatic Impairment:** Use with caution; monitor for signs of hepatotoxicity.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, or other NSAIDs (risk of cross-sensitivity).
* Active peptic ulceration or inflammatory bowel disease.
* History of GI bleeding or perforation related to previous NSAID therapy.
* Pre-operative pain management in the setting of coronary artery bypass graft (CABG) surgery.
* Severe heart failure.
## Adverse Effects
* **Gastrointestinal:** Nausea, diarrhea (most common), abdominal pain, dyspepsia, risk of GI ulceration/bleeding.
* **Renal:** Fluid retention, edema, potential for acute kidney injury.
* **Hematologic:** Potential for anemia or blood dyscrasias with long-term use.
* **CNS:** Dizziness, headache, drowsiness.
## Key Drug Interactions
* **Anticoagulants (e.g., Warfarin):** Increased risk of bleeding.
* **Antiplatelet agents/SSRIs:** Increased risk of GI bleeding.
* **Antihypertensives (ACE inhibitors, Diuretics, Beta-blockers):** Reduced efficacy of antihypertensive therapy and increased risk of renal impairment.
* **Lithium/Methotrexate:** Decreased renal clearance leading to increased toxicity.
## Monitoring
* Monitor for signs of GI bleeding (melena, hematemesis).
* Periodic renal function tests (BUN/SCr) and blood pressure monitoring in chronic users.
* Observe for signs of fluid retention or peripheral edema.
## Clinical Pearls
* **Diarrhea Risk:** Mefenamic acid is notoriously associated with diarrhea; if it develops, discontinue the medication.
* **Administration:** Administer with food or milk to decrease gastrointestinal irritation.
* **Duration:** Due to the risk of hemolytic anemia and hepatotoxicity with prolonged use, it is not indicated for chronic pain conditions.
* **Pediatric Safety:** Ensure the weight-based dose is strictly followed to prevent toxicity.
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**Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Prescribing practices vary by region and clinical context. Always consult the latest package insert, your institution's formulary, or local treatment guidelines before prescribing or administering medication.
