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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is an anthranilic acid derivative nonsteroidal anti-inflammatory drug (NSAID). It exhibits analgesic, anti-inflammatory, and antipyretic properties via the inhibition of cyclooxygenase (COX-1 and COX-2) enzymes, leading to reduced prostaglandin synthesis.
## Primary Indications
* Mild to moderate pain, including primary dysmenorrhea.
* Short-term management of acute pain (not to exceed 7 days).
* Antipyretic use in pediatric populations (Meftal-P contains mefenamic acid/paracetamol combination in some markets; verify formulation).
## Adult Dosing
* **Acute Pain/Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed.
* **Maximum Duration:** 7 days.
* **Maximum Daily Dose:** Do not exceed 1.5 g total daily dose.
## Pediatric Dosing
* **Note:** Always verify specific regional labeling (e.g., Meftal-P is often formulated for children).
* **Antipyretic/Analgesic:** Generally 6.5 mg/kg body weight per dose, administered every 6–8 hours as needed.
* **Safety Note:** Use is typically restricted to children >6 months of age. Consult local clinical protols for age-stratified dosing limits.
## Dose Adjustments
* **Renal Impairment:** Contraindicated or requires significant caution in patients with severe renal impairment (CrCl <30 mL/min).
* **Hepatic Impairment:** Use with caution; monitor liver function tests. Dose reduction may be necessary.
* **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).
* Active peptic ulceration, inflammatory bowel disease, or GI bleeding.
* Severe heart failure, severe renal or hepatic impairment.
* Pre-operative pain management in the setting of coronary artery bypass graft (CABG) surgery.
## Adverse Effects
* **Common:** Nausea, abdominal pain, diarrhea (often dose-limiting), and dyspepsia.
* **Serious:** GI ulceration or hemorrhage, fluid retention, cardiovascular thrombotic events, nephrotoxicity, and skin reactions (e.g., Stevens-Johnson Syndrome).
## Key Drug Interactions
* **Anticoagulants/Antiplatelets (e.g., Warfarin):** Increased risk of bleeding.
* **ACE Inhibitors/ARBs/Diuretics:** Reduced antihypertensive effect and increased risk of acute renal failure.
* **Lithium/Methotrexate:** NSAIDs may decrease clearance, increasing toxicity risk.
* **Corticosteroids/SSRIs:** Increased risk of gastrointestinal ulceration.
## Monitoring
* **Renal/Hepatic:** Periodic monitoring of serum creatinine, BUN, and LFTs for chronic use.
* **Hematologic:** Monitor for signs of occult GI blood loss (e.g., anemia).
* **Cardiovascular:** Monitor blood pressure during initiation and maintenance.
## Clinical Pearls
* **GI Sensitivity:** Take with food or milk to minimize gastrointestinal discomfort.
* **Non-Selective:** As a non-selective COX inhibitor, its GI toxicity profile is significant; it should not be used as a first-line agent for chronic pain.
* **Combination Products:** If using "Meftal-P," confirm if it contains paracetamol to avoid double-dosing of acetaminophen.
* **Diarrhea:** Mefenamic acid is uniquely associated with diarrhea; if it develops, discontinue the drug immediately.
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**Educational Disclaimer:** This information is provided for educational purposes and does not constitute medical advice. Prescribing practices and availability may vary significantly by region. Always verify specific dosing, safety warnings, and contraindications against current institutional protocols, local regulatory product inserts, or reputable pharmacology databases (e.g., BNF, Lexicomp) prior to prescribing or administration.
