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# Meftal (Mefenamic Acid)
## Overview
Mefenamic acid is an anthranilic acid derivative nonsteroidal anti-inflammatory drug (NSAID). It exhibits analgesic, anti-inflammatory, and antipyretic properties by inhibiting cyclooxygenase (COX-1 and COX-2) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Treatment of primary dysmenorrhea.
* Mild to moderate pain relief (short-term use, typically ≤7 days).
## 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
* **Adolescents (≥14 years):** Dosing is the same as adults (500 mg initial, then 250 mg every 6 hours).
* **Children (<14 years):** Safety and efficacy are not established. Use is generally avoided in this demographic.
## Dose Adjustments
* **Renal Impairment:** Contraindicated in severe renal impairment. Use with extreme caution in mild-to-moderate impairment; reduced dosing or frequency may be required.
* **Hepatic Impairment:** Use with caution; monitor for signs of liver toxicity.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of asthma or allergic-type reactions induced by aspirin or other NSAIDs.
* Active peptic ulceration or inflammatory bowel disease.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Severe renal or hepatic failure.
## Adverse Effects
* **Gastrointestinal:** Nausea, abdominal pain, diarrhea (common), peptic ulceration, and GI bleeding.
* **Renal:** Fluid retention, edema, renal impairment/failure.
* **Hematologic:** Anemia, leukopenia, thrombocytopenia (rare, with long-term use).
* **CNS:** Dizziness, headache, drowsiness.
* **Dermatologic:** Rash, Stevens-Johnson syndrome (rare).
## Key Drug Interactions
* **Anticoagulants (e.g., Warfarin):** Increased risk of bleeding due to platelet inhibition and GI mucosal injury.
* **Anti-hypertensives:** Reduces the efficacy of ACE inhibitors, ARBs, and diuretics.
* **Other NSAIDs/Corticosteroids:** Increased risk of GI ulceration and hemorrhage.
* **Lithium/Methotrexate:** NSAIDs can decrease renal clearance of these drugs, increasing toxicity.
## Monitoring
* Monitor hemoglobin/hematocrit and fecal occult blood if used beyond short-term durations.
* Serial assessment of renal function (BUN/Creatinine) and blood pressure.
* Monitor for signs of GI distress or hepatotoxicity.
## Clinical Pearls
* **GI Protection:** Always advise patients to take the medication with food or milk to minimize gastrointestinal irritation.
* **Diarrhea:** Mefenamic acid is uniquely associated with a higher incidence of diarrhea compared to other NSAIDs; if severe, discontinue the drug.
* **Cardiovascular Risk:** Like all NSAIDs, it may increase the risk of serious thrombotic events, myocardial infarction, and stroke.
* **Short-term Use:** It is not intended for chronic pain management. Always verify institutional protocols regarding duration limits.
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**Educational Disclaimer:** This information is for educational purposes only. Always consult the most current local prescribing information, clinical guidelines, or a practicing pharmacist before administering or prescribing any medication.
