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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. Like other NSAIDs, it inhibits cyclooxygenase (COX-1 and COX-2) enzymes, reducing prostaglandin synthesis.
## Primary Indications
* Primary dysmenorrhea (short-term use, ≤ 7 days).
* Mild to moderate pain.
* *Note:* Use in rheumatologic conditions is generally superseded by other NSAIDs due to safety profiles.
## Adult Dosing
* **Standard Dose:** 500 mg initially, followed by 250 mg every 6 hours as needed.
* **Maximum Duration:** Usually limited to 1 week due to the risk of gastrointestinal and renal toxicity.
## Pediatric Dosing
* **Children > 14 years:** Follow adult dosing.
* **Children < 14 years:** Safety and efficacy are not well established. Its use is generally discouraged in pediatrics unless directed by a specialist, as safer alternatives (e.g., ibuprofen, acetaminophen) are preferred for antipyresis and pain. If used: 6.5 mg/kg every 8 hours (limited to 5 days).
## Dose Adjustments
* **Renal Impairment:** Avoid in severe renal impairment (CrCl < 30 mL/min). Use with caution in moderate impairment; dosage reduction may be required.
* **Hepatic Impairment:** Use with caution; monitor liver enzymes. Discontinue if abnormal liver function tests persist.
* **Geriatric:** Use the lowest effective dose for the shortest duration due to increased risk of GI bleeding and cardiovascular events.
## Contraindications
* Known hypersensitivity to mefenamic acid or other NSAIDs (including aspirin-sensitive asthma).
* History of active gastrointestinal ulceration or inflammatory bowel disease.
* Perioperative setting of coronary artery bypass graft (CABG) surgery.
* Severe renal or hepatic failure.
* Third trimester of pregnancy (risk of premature closure of ductus arteriosus).
## Adverse Effects
* **Common:** Abdominal pain, nausea, diarrhea, dyspepsia, dizziness.
* **Serious:** GI bleeding, ulceration, peptic perforation, cardiovascular events (MI, stroke), acute renal failure, interstitial nephritis, and hemolytic anemia (with chronic use).
## Key Drug Interactions
* **Anticoagulants (Warfarin):** Increases risk of bleeding.
* **Other NSAIDs/Aspirin:** Increases risk of GI toxicity and bleeding.
* **ACE Inhibitors/ARBs/Diuretics:** Reduces antihypertensive efficacy and increases risk of acute kidney injury.
* **Lithium/Methotrexate:** Increases serum concentrations and toxicity risk.
## Monitoring
* Baseline and periodic monitoring of renal function, blood pressure, and hemoglobin (if long-term/chronic use occurs).
* Monitor for signs of GI bleeding (melena, hematemesis).
* Assess for edema or worsening of heart failure.
## Clinical Pearls
* **Take with food:** Administration with food or milk helps minimize gastric irritation.
* **Short-term only:** Meftal-P is intended for acute, short-term management. Chronic, long-term use increases the risk of serious hematologic and GI adverse effects significantly more than other common NSAIDs.
* **Avoid in dehydration:** Advise patients to maintain adequate hydration to reduce renal stress while taking the medication.
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**Educational Disclaimer:** This information is for educational purposes and does not substitute for professional medical judgment. Prescribing information, local guidelines, and regulatory approvals vary by region. Always verify official product monographs and institutional protocols before prescribing or administering medication.
