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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the anthranilic acid derivative class. 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 every 4 to 6 hours as needed. Do not exceed 1500 mg in a 24-hour period for the first 7 days of treatment, and do not exceed 1000 mg in a 24-hour period if treatment continues beyond 7 days.
* **Dysmenorrhea:** 500 mg every 4 to 6 hours as needed, typically starting with the onset of pain or bleeding. Do not exceed 1500 mg in a 24-hour period.
## Pediatric Dosing
* Mefenamic acid is generally not recommended for children under 14 years of age due to lack of established safety and efficacy.
## Dose Adjustments
* No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised. Mefenamic acid should be used with caution in patients with pre-existing renal or hepatic disease.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of gastrointestinal bleeding or perforation related to NSAID use.
* Active peptic ulceration or history of recurrent peptic ulceration.
* Severe heart failure, severe renal impairment, or severe hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include nausea, vomiting, diarrhea, abdominal pain, constipation, and dyspepsia. Serious adverse effects can include gastrointestinal bleeding, ulceration, perforation, cardiovascular thrombotic events, renal failure, hepatic failure, and hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal adverse effects.
* **Selective Serotonin Reuptake Inhibitors (SSRIs):** Increased risk of gastrointestinal bleeding.
* **Other NSAIDs or Salicylates:** Increased risk of adverse effects, particularly gastrointestinal.
* **ACE inhibitors, ARBs, diuretics:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding or perforation.
* Assess renal and hepatic function, especially in patients with pre-existing disease or those on long-term therapy.
* Monitor for cardiovascular events.
* Assess for hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Limit duration of use to the shortest possible time necessary for symptom control.
* Avoid concomitant use with other NSAIDs.
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*This information is intended for healthcare professionals and does not substitute for comprehensive prescribing information. Always consult the official drug prescribing information and relevant clinical guidelines before making any treatment decisions.*
