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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term treatment of mild to moderate pain, including menstrual pain. It works by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Mild to moderate pain
* Primary dysmenorrhea
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Do not exceed 1500 mg in 24 hours.
* **Primary Dysmenorrhea:** 500 mg every 6 hours as needed, starting at the onset of pain and bleeding. Treatment should not exceed 5 days per cycle.
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age due to lack of established safety and efficacy data.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised. Use the lowest effective dose for the shortest duration necessary.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, 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.
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include nausea, vomiting, diarrhea, abdominal pain, constipation, and headache. More serious adverse effects include gastrointestinal bleeding, ulceration, perforation, myocardial infarction, stroke, hypertension, and renal toxicity.
## 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 gastrointestinal bleeding.
* **Lithium:** Increased lithium levels and potential toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
* **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect and increased risk of renal impairment.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor for signs and symptoms of cardiovascular events (e.g., chest pain, shortness of breath).
* Monitor renal function, especially in patients with pre-existing renal disease or those on concomitant nephrotoxic agents.
* Monitor blood pressure.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Limit duration of use to the shortest possible time to manage symptoms.
* Consider the risks of NSAIDs (GI bleeding, cardiovascular events, renal toxicity) in all patients, particularly the elderly and those with pre-existing conditions.
* It is generally recommended to avoid concurrent use with other NSAIDs.
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This information is intended for clinical use and does not replace the need to consult the official prescribing information and relevant literature. Always verify current prescribing information for the most up-to-date details.
