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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term management of mild to moderate pain. It functions by inhibiting prostaglandin synthesis.
## Primary Indications
* Short-term treatment of mild to moderate pain, including menstrual pain (dysmenorrhea).
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, starting at the onset of pain and menstrual flow.
* **Maximum Dose:** Not to exceed 1250 mg in any 24-hour period. Treatment should not exceed 7 days.
## Pediatric Dosing
* **Age Limit:** Generally not recommended for children under 14 years of age due to limited data.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustment is established, but monitor renal function closely.
* **Hepatic Impairment:** Use with caution. No specific dose adjustment is established.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of gastrointestinal (GI) bleeding or perforation related to previous NSAID use.
* Active peptic ulceration or history of recurrent peptic ulceration.
* Severe heart failure.
* Late pregnancy (third trimester).
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, constipation, dizziness, headache.
* **Serious:** Gastrointestinal bleeding, perforation, ulceration; renal toxicity; cardiovascular thrombotic events; hypersensitivity reactions; Stevens-Johnson syndrome; toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of GI adverse effects and may reduce cardioprotective effects of low-dose aspirin.
* **Selective Serotonin Reuptake Inhibitors (SSRIs):** Increased risk of GI bleeding.
* **Diuretics, ACE inhibitors, Angiotensin II Receptor Blockers (ARBs):** May reduce antihypertensive effect and increase risk of renal dysfunction.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* **Gastrointestinal:** Monitor for signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* **Renal:** Monitor renal function, especially in patients with pre-existing renal disease or those taking concomitant nephrotoxic agents.
* **Cardiovascular:** Assess for signs of fluid retention or worsening heart failure.
* **Hepatic:** Monitor liver function tests if symptoms suggest liver dysfunction.
## Clinical Pearls
* Mefenamic acid is for short-term use only.
* Administer with food or milk to minimize GI upset.
* Due to a higher incidence of diarrhea compared to other NSAIDs, use with caution in patients with inflammatory bowel disease.
**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and clinical guidelines for definitive patient care decisions.
