Mefatal

# mefatal ## Overview - **Classification**: Nonsteroidal Anti-inflammatory Drug (NSAID) - **Mechanism**: Inhibits cyclooxygenase (COX-1 and COX-2) enzymes, reducing prostaglandin synthesis, thereby exerting analgesic, anti-inflammatory, and antipyretic effects. ## Primary Indications 1. **Acute Pain** - Mild to moderate pain for short-term use. 2. **Primary Dysmenorrhea** - Menstrual pain relief. 3. **Menorrhagia** - Reduction of excessive menstrual bleeding (off-label or in some regions). ## Adult Dosing ### Standard Dosing **Acute Pain / Primary Dysmenorrhea** - **Dose**: **500 mg** - **Frequency**: Initial dose, then **250 mg every 6 hours** - **Route**: Oral - **Duration**: Not to exceed **7 days** ### Dose Adjustments - **Renal Impairment**: **Not recommended** due to risk of renal toxicity. Avoid use in advanced renal disease. - **Hepatic Impairment**: Use with **caution**. Consider reduced doses and monitor liver function. Avoid in severe hepatic impairment. - **Elderly Patients**: Use **lowest effective dose** for shortest duration due to increased risk of GI, renal, and cardiovascular adverse effects. ## Pediatric Dosing *Mefenamic acid is generally not recommended for children under 14 years due to limited safety data and risk of adverse effects.* ### Neonates (0-28 days) - **Not recommended**. Contraindicated. ### Infants (1-12 months) - **Not recommended**. Contraindicated. ### Children (1-12 years) - **Generally not recommended**. Safety and efficacy not established. If used, typically **6.5 mg/kg/day** in divided doses. - **Frequency**: Typically **every 6 hours**. - **Maximum**: **250 mg/dose** for children, not to exceed **1500 mg/day**. - **Special Notes**: Use only if benefits outweigh risks, and other options are unsuitable. Monitor closely for GI and renal effects. ### Adolescents (13-18 years) - **Dose**: Start with **adult dosing (500 mg initial, then 250 mg q6h)**. - **Maximum**: **7 days** duration, **1250 mg/day**. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs. - **Absolute**: History of aspirin-induced asthma, urticaria, or allergic-type reactions. - **Absolute**: Active gastrointestinal (GI) bleeding or peptic ulcer disease. - **Absolute**: Severe renal or hepatic impairment. - **Absolute**: Coronary artery bypass graft (CABG) surgery peri-operative pain. - **Absolute**: Third trimester of pregnancy (premature closure of ductus arteriosus). ### Common Adverse Effects - **Very Common (>10%)**: Diarrhea, abdominal pain. - **Common (1-10%)**: Nausea, vomiting, dyspepsia, constipation, dizziness, headache, rash. - **Serious but Rare**: Gastrointestinal bleeding, perforation, renal failure, acute liver injury, cardiovascular thrombotic events (MI, stroke), severe skin reactions (SJS, TEN), anaphylaxis, aseptic meningitis. ### Key Drug Interactions - **Anticoagulants (Warfarin)**: Increased risk of bleeding. Monitor INR closely. - **Lithium**: Increased lithium levels, leading to toxicity. Monitor lithium levels. - **Diuretics (Furosemide, Thiazides)**: Reduced diuretic and antihypertensive effect. Monitor blood pressure. - **ACE Inhibitors / ARBs**: Increased risk of renal impairment. Monitor renal function. - **Methotrexate**: Increased methotrexate levels, leading to toxicity. Avoid concomitant use if possible. - **Corticosteroids / SSRIs**: Increased risk of GI bleeding. Use with caution. ## Monitoring & Follow-up - **Before Treatment**: Assess renal function (SCr, BUN), CBC, liver function tests (LFTs) in patients with risk factors. - **During Treatment**: Monitor for signs of GI bleeding (black stools, vomiting blood), peripheral edema, and changes in blood pressure. - **Clinical Signs**: Watch for persistent abdominal pain, unexplained fatigue, dark urine, yellowing of skin/eyes (jaundice), severe rash. ## Clinical Pearls - 💡 **Short-term Use**: Mefenamic acid should be used for the **shortest possible duration** (typically up to 7 days) to minimize adverse effects. - 💡 **Take with Food**: Advise patients to take with food, milk, or antacids to **reduce GI upset**. - 💡 **Hydration**: Ensure adequate hydration to **reduce risk of renal toxicity**, especially in patients with pre-existing renal conditions. - 💡 **Diarrhea Risk**: Mefenamic acid is notable for a higher incidence of **diarrhea** compared to other NSAIDs. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.