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# Mefenamic Acid (Meftal)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) that exhibits analgesic, anti-inflammatory, and antipyretic properties. It acts primarily by inhibiting the cyclooxygenase (COX-1 and COX-2) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Management of mild to moderate pain.
* Primary dysmenorrhea.
* *Note:* Use should generally be limited to short-term treatment (typically ≤ 7 days).
## Adult Dosing
* **Initial Dose:** 500 mg orally as a loading dose.
* **Maintenance Dose:** 250 mg orally every 6 hours as needed.
* **Maximum Duration:** Do not exceed 7 days of treatment due to increased risk of toxicity.
## Pediatric Dosing
* **Age >14 years:** Use adult dosing (500 mg initial, followed by 250 mg every 6 hours).
* **Age <14 years:** Safety and efficacy have not been firmly established. Use should be avoided unless under specialized pediatric rheumatology guidance.
## 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 elevated transaminases. Avoid in severe hepatic failure.
## Contraindications
* Known hypersensitivity to mefenamic acid or other NSAIDs (including aspirin-induced asthma/urticaria).
* History of active peptic ulceration or inflammatory bowel disease.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* History of renal or hepatic failure.
## Adverse Effects
* **Gastrointestinal:** Diarrhea (common), nausea, dyspepsia, GI bleeding, ulceration.
* **Renal:** Fluid retention, edema, acute renal failure, interstitial nephritis.
* **Hematologic:** Anemia (potential for prolonged use-related bleeding).
* **Neurologic:** Dizziness, headache, drowsiness.
* **Serious:** Increased risk of thrombotic cardiovascular events (e.g., MI, stroke).
## Key Drug Interactions
* **Anticoagulants (e.g., Warfarin):** Increased risk of bleeding.
* **Anti-platelet agents (e.g., Clopidogrel, Aspirin):** Increased risk of GI toxicity and bleeding.
* **ACE Inhibitors/ARBs/Diuretics:** Reduced antihypertensive effect and increased risk of renal impairment (nephrotoxicity).
* **Lithium:** May increase serum lithium levels, leading to toxicity.
* **Methotrexate:** May increase methotrexate levels, increasing risk of toxicity.
## Monitoring
* **Renal Function:** Serum creatinine and electrolytes for long-term or high-risk patients.
* **GI:** Monitor for signs/symptoms of occult or overt GI bleeding.
* **Blood Pressure:** Monitor for new or worsening hypertension.
## Clinical Pearls
* **Administration:** Take with food or milk to minimize potential gastrointestinal irritation.
* **Duration:** Mefenamic acid is specifically indicated for short-term use; chronic use is not recommended due to a higher incidence of diarrhea and systemic NSAID toxicities compared to other agents.
* **Pediatric Warning:** In some markets (such as India), "Meftal-P" is marketed as a pediatric suspension; however, clinical guidelines in many regions (e.g., US/EU) discourage its use in children due to limited safety data. Always adhere to local prescribing guidelines.
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*Disclaimer: This information is for educational purposes only. Drug dosing, contraindications, and regulatory indications can vary by region and clinical context. Always verify dosages and safety information against official prescribing information (package insert) or local hospital protocols before prescribing or administering medication.*
