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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) with analgesic and anti-inflammatory properties. It functions by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain.
* Primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed.
* **Dysmenorrhea:** 500 mg orally every 6 hours as needed, typically initiated at the onset of bleeding and associated pain.
* **Maximum Daily Dose:** 1500 mg (for short-term use, up to 7 days).
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age due to potential for side effects, including diarrhea and gastrointestinal upset. If used, dosing is typically based on weight and is at the discretion of the prescriber, often mirroring adult dosing on a weight-based calculation, but specific established pediatric guidelines are limited. Consult pediatric-specific resources or local protocols.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised, and lowest effective doses should be used. Monitor patients closely for adverse effects.
## 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.
* Active gastrointestinal bleeding or history of recurrent GI ulceration/bleeding.
* Severe renal, hepatic, or cardiac impairment.
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include diarrhea, nausea, vomiting, abdominal pain, constipation, dyspepsia, and dizziness. Serious adverse effects can include GI ulceration and bleeding, renal toxicity, cardiovascular thrombotic events, hepatotoxicity, and hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Aspirin:** May decrease the antiplatelet effect of low-dose aspirin; increased risk of GI toxicity.
* **ACE inhibitors, ARBs, Diuretics:** May decrease antihypertensive effect and increase risk of renal impairment.
* **Lithium, Methotrexate:** Increased serum levels and toxicity.
## Monitoring
* **GI symptoms:** Watch for signs of bleeding or ulceration.
* **Renal function:** Monitor BUN and creatinine, especially in patients with pre-existing renal disease or those on concomitant nephrotoxic agents.
* **Hepatic function:** Monitor LFTs if treatment is prolonged or in patients with liver disease.
* **Blood pressure:** Monitor for potential increases.
## Clinical Pearls
* Mefenamic acid should be used for the shortest duration necessary to control symptoms.
* It is generally reserved for situations where other NSAIDs are not effective or tolerated.
* Diarrhea is a common and dose-limiting side effect.
* Caution is advised in patients with cardiovascular risk factors.
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*This information is intended for clinical professionals. Always consult the most current prescribing information and institutional protocols before making clinical decisions.*
