Mefenemic%25252520acid

# Mefenamic Acid ## Overview Mefenamic acid is an anthranilic acid derivative nonsteroidal anti-inflammatory drug (NSAID). It exerts its effects primarily through the non-selective inhibition of cyclooxygenase (COX-1 and COX-2) enzymes, leading to reduced prostaglandin synthesis. ## Primary Indications * Treatment of primary dysmenorrhea. * Short-term relief of mild to moderate pain (typically ≤7 days). ## Adult Dosing * **Dysmenorrhea/Pain:** 500 mg orally initially, followed by 250 mg every 6 hours as needed. * **Maximum Dose:** Do not exceed 1,500 mg per day and do not use for longer than 7 days. ## Pediatric Dosing * **Children ≥14 years:** Use adult dosing regimen. * **Children <14 years:** Safety and efficacy have not been established. Not recommended. ## Dose Adjustments * **Renal Impairment:** Use with caution. Generally contraindicated in severe renal impairment (CrCl <30 mL/min). * **Hepatic Impairment:** Use with caution. Discontinue if liver function tests become abnormal or if signs/symptoms of liver disease develop. * **Geriatric:** Increased risk for serious gastrointestinal (GI) adverse events; use the lowest effective dose for the shortest duration. ## Contraindications * Known hypersensitivity to mefenamic acid or other NSAIDs (including aspirin-induced asthma/urticaria). * History of asthma precipitated by aspirin or NSAIDs. * Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery. * Active peptic ulcer disease or GI bleeding. * Severe renal or hepatic impairment. ## Adverse Effects * **GI:** Diarrhea (most common), nausea, vomiting, abdominal pain, increased risk of GI ulceration or hemorrhage. * **Renal:** Fluid retention, edema, transient elevation of serum creatinine, acute renal failure. * **Cardiovascular:** Increased risk of serious thrombotic events (myocardial infarction, stroke), hypertension. * **Hematologic:** Anemia, blood dyscrasias. * **Other:** Dizziness, headache, skin rash, pruritus. ## Key Drug Interactions * **Anticoagulants (e.g., Warfarin):** Increased risk of bleeding; monitor INR closely. * **Antiplatelet agents/SSRIs:** Increased risk of GI toxicity and bleeding. * **Antihypertensives (ACE inhibitors, ARBs, Diuretics):** NSAIDs may decrease the antihypertensive effect; increased risk of nephrotoxicity. * **Lithium/Methotrexate:** NSAIDs may reduce renal clearance, increasing systemic exposure and toxicity risk. ## Monitoring * **GI:** Monitor for signs of occult blood or gastric distress. * **Renal/Hepatic:** Periodic monitoring of serum creatinine, BUN, and liver transaminases (ALT/AST) during long-term use. * **Blood Pressure:** Regular monitoring in patients with hypertension. * **Hematology:** Periodically check complete blood count (CBC) if used for >1 week. ## Clinical Pearls * **Administration:** Take with food or milk to minimize gastric irritation. * **Diarrhea:** Diarrhea is a dose-related adverse effect; if severe diarrhea occurs, the drug should be discontinued promptly. * **Black Box Warning:** All NSAIDs carry a warning regarding the increased risk of serious cardiovascular thrombotic events and serious GI adverse events. * **Cross-reactivity:** Use caution in patients with aspirin-sensitive asthma due to potential cross-reactivity. *** *Disclaimer: This information is for educational purposes only. Always consult current, reputable clinical resources or institutional protocols, and refer to the manufacturer’s package insert for the most recent prescribing information before administration.*