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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It possesses analgesic, anti-inflammatory, and antipyretic properties, primarily through the inhibition of cyclooxygenase (COX) enzymes, thus 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 as needed, typically started at the onset of pain and bleeding, and continued for up to 3 days.
* **Maximum:** Do not exceed 4000 mg per day.
## Pediatric Dosing
* **Pain/Dysmenorrhea:** 6.5 mg/kg every 6 hours as needed.
* **Maximum:** Not to exceed adult doses. This dosing is generally for children aged 14 years and younger. Safety and efficacy in younger children are not well-established.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised. Mefenamic acid should be used with caution in patients with pre-existing renal or hepatic disease.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* 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.
* Severe heart failure.
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include:
* Gastrointestinal: Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation.
* Central Nervous System: Dizziness, drowsiness.
* Renal: Acute kidney injury (less common but serious).
* Hematologic: Anemia, leukopenia.
* Other: Rash, pruritus, headache.
Serious adverse effects include GI bleeding, ulceration, perforation, cardiovascular thrombotic events, myocardial infarction, stroke, renal failure, and hepatic failure.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **Diuretics, ACE Inhibitors, ARBs:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor renal function, especially in patients with pre-existing renal disease or those taking concurrent nephrotoxic agents.
* Monitor blood pressure.
* Assess for signs of hypersensitivity or allergic reactions.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only.
* Administer with food or milk to minimize gastrointestinal upset.
* Avoid concomitant use with other NSAIDs.
* Discontinue use if any signs of adverse GI effects, renal toxicity, or hypersensitivity occur.
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*Disclaimer: This information is intended for healthcare professionals and does not replace the need to consult the official prescribing information or a current drug compendium. Always verify current product information before prescribing or dispensing.*
