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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to 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. Do not exceed 1500 mg in the first 24 hours of treatment, and do not exceed 1000 mg for any single dose.
* **Dysmenorrhea:** 500 mg every 6 hours starting at the onset of pain or bleeding, whichever comes first, and continuing for the duration of the symptoms, usually 2-3 days.
## Pediatric Dosing
Mefenamic acid is **not recommended** for use in pediatric patients under 14 years of age due to lack of established efficacy and safety.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, however, caution is advised. NSAIDs can lead to renal toxicity, and patients with pre-existing renal disease are at higher risk.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* Patients who have experienced 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).
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include diarrhea, nausea, vomiting, abdominal pain, constipation, and headache. Serious adverse effects include gastrointestinal bleeding, ulceration, perforation, cardiovascular thrombotic events, renal toxicity, hepatic reactions, and hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs):** Increased risk of bleeding.
* **Other NSAIDs/Aspirin:** Increased risk of adverse effects, particularly gastrointestinal bleeding.
* **Diuretics and Antihypertensives:** May decrease their efficacy 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.
* Monitor for signs of cardiovascular events.
* Monitor renal and hepatic function, especially in patients with pre-existing conditions or those on long-term therapy.
* Monitor for signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid should be used for the shortest duration necessary to control symptoms.
* Administer with food or milk to minimize gastrointestinal upset.
* Due to the risk of diarrhea, which can be severe, patients should be instructed to discontinue the drug and seek medical attention if severe diarrhea occurs.
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*This information is intended for healthcare professionals. Always consult the official prescribing information and current clinical guidelines for complete details before making any treatment decisions.*
