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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) of the fenamate class. It functions by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Dysmenorrhea:** 500 mg every 6 hours starting at the onset of pain or bleeding and continuing for the duration of symptoms, not to exceed 7 days in any month.
## Pediatric Dosing
* **Age < 6 months:** Safety and efficacy not established.
* **Age $\ge$ 6 months:** Dosing is typically based on weight, but specific pediatric dosing is not universally established and may vary by product labeling or local protocol. A common recommendation is 6.5 mg/kg every 6 hours.
## Dose Adjustments
No dose adjustments are typically required for renal or hepatic impairment, but caution is advised due to potential for NSAID-associated toxicity. Use the lowest effective dose for the shortest duration necessary.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis).
* Severe heart failure.
* Severe renal impairment.
* Severe hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), dyspepsia, headache, dizziness, and rash. Serious adverse effects include gastrointestinal bleeding, ulceration, perforation, renal toxicity, cardiovascular thrombotic events, and hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **ACE inhibitors and ARBs:** Reduced antihypertensive effect; increased risk of renal impairment.
* **Diuretics:** Reduced diuretic and antihypertensive effect; increased risk of renal impairment.
* **Lithium:** Increased lithium levels and risk of toxicity.
* **Methotrexate:** Increased methotrexate levels and risk of toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding.
* Monitor renal function, especially in patients with pre-existing renal disease or those taking concomitant nephrotoxic agents.
* Monitor for signs of cardiovascular events.
* Assess pain relief and efficacy.
## Clinical Pearls
* Should be taken with food or milk to minimize gastrointestinal upset.
* Limit duration of use to 7 days for pain management due to potential for serious adverse effects with prolonged use.
* Use with caution in patients with pre-existing heart failure, hypertension, or edema.
* Consider alternative analgesics if patients have a history of peptic ulcer disease or gastrointestinal bleeding.
*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines for definitive guidance. Dosing and safety information can vary based on product formulation and patient-specific factors.*
