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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits prostaglandin synthesis.
## Primary Indications
* Short-term treatment of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Maximum daily dose is 1500 mg. Treatment should not exceed 7 days.
* **Dysmenorrhea:** 500 mg every 6 hours starting at the onset of pain and bleeding, and continuing for the duration of the symptoms.
## Pediatric Dosing
Dosing in pediatric patients is not well-established and should be determined by a physician based on age, weight, and clinical condition.
## Dose Adjustments
No specific dose adjustments are necessary for renal or hepatic impairment, but caution is advised, and close monitoring for adverse effects is recommended due to potential for accumulation and toxicity.
## 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.
* Severe renal or hepatic impairment.
* Active gastrointestinal bleeding or ulceration.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, dyspepsia, constipation, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal failure; hepatotoxicity; cardiovascular thrombotic events; exacerbation of asthma; Stevens-Johnson syndrome; toxic epidermal necrolysis; anaphylaxis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal adverse effects.
* **SSRIs/SNRIs:** Increased risk of bleeding.
* **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect and increased risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate levels and toxicity.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Renal function (BUN, creatinine).
* Liver function (ALT, AST).
* Blood pressure.
* For signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid has a relatively short duration of action; frequent dosing is required.
* Due to its gastrointestinal side effect profile, it should be used at the lowest effective dose for the shortest duration necessary.
* Avoid use in patients with pre-existing renal or hepatic disease.
* The risk of cardiovascular events, though less studied with mefenamic acid compared to other NSAIDs, is still a concern.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant literature for complete and up-to-date drug details, including dosages, contraindications, warnings, precautions, and adverse reactions, before making any clinical decisions. This document does not replace professional medical judgment.
