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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.
## Primary Indications
* Pain, including menstrual pain (dysmenorrhea)
* Pain associated with inflammation
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Do not exceed 4000 mg per day. Treatment duration should generally not exceed 7 days.
* **Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed. Start at the onset of menstrual pain and continue for the duration of the pain, up to 7 days.
## Pediatric Dosing
Mefenamic acid is **not recommended** for children under 14 years of age due to lack of established efficacy and safety data in this population.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustment guidelines are established, but renal function should be monitored.
* **Hepatic Impairment:** Use with caution. No specific dose adjustment guidelines are established.
## 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.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, constipation, dizziness, headache, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal toxicity; hypersensitivity reactions; hepatic dysfunction.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Aspirin:** Mefenamic acid may reduce the cardioprotective effects of low-dose aspirin.
* **Lithium:** Increased lithium levels, risk of toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
* **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect and increased risk of renal impairment.
## Monitoring
* **Renal function:** Especially in patients with pre-existing renal disease or those at risk.
* **Hepatic function:** Particularly with prolonged use or in patients with liver disease.
* **Signs and symptoms of GI bleeding:** Black, tarry stools, hematemesis, epigastric pain.
* **Blood pressure:** NSAIDs can elevate blood pressure.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only.
* Patients should be advised to report any signs of GI bleeding or other serious adverse effects immediately.
* Due to the potential for diarrhea, ensure adequate hydration, especially in elderly patients or those with other risk factors.
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*This information is intended for clinical use and does not substitute for professional medical judgment. Always consult the most current prescribing information and relevant guidelines before making treatment decisions.*
