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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It exerts analgesic and anti-inflammatory effects 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 orally every 6 hours as needed.
* **Dysmenorrhea:** 500 mg orally every 6 hours, usually initiated at the onset of bleeding and associated pain.
* **Maximum daily dose:** 1500 mg.
* **Duration:** Not intended for use longer than 7 days.
## Pediatric Dosing
* Mefenamic acid is generally not recommended for children under 14 years of age due to limited safety and efficacy data.
* If used, dosing is typically based on weight, but specific recommendations are scarce and should be guided by expert consultation or local protocols.
## Dose Adjustments
* No specific dose adjustments are routinely required for renal or hepatic impairment, but caution is advised due to potential for renal and hepatic toxicity with NSAIDs. 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.
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), dizziness, and headache. Serious adverse effects may include gastrointestinal bleeding, ulceration, perforation, renal toxicity, hepatic 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.
* **Other NSAIDs (including aspirin):** Increased risk of adverse effects, particularly gastrointestinal.
* **ACE inhibitors, Angiotensin II Receptor Blockers (ARBs), Diuretics:** May diminish the antihypertensive effect and increase the risk of renal impairment.
* **Lithium:** Increased serum lithium levels and risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor renal function (BUN, creatinine) especially in patients with pre-existing renal disease or those on concomitant nephrotoxic agents.
* Monitor liver function tests if prolonged use is considered or if signs of hepatic dysfunction appear.
* Monitor for signs of cardiovascular events.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Use the lowest effective dose for the shortest duration necessary to minimize risks.
* Avoid concurrent use with other NSAIDs.
* Consider the risk of renal toxicity, especially in the elderly or those with risk factors.
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*This information is intended for healthcare professionals and does not replace the need to consult the official prescribing information or local guidelines.*
