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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term relief of mild to moderate pain, particularly dysmenorrhea. It functions by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Pain (mild to moderate)
* 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 bleeding.
* **Maximum Duration:** Not recommended for use for more than 7 consecutive days.
## Pediatric Dosing
Mefenamic acid is generally not recommended for use in pediatric patients under 14 years of age due to lack of established dosing and safety data.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Patients with severe renal impairment should avoid mefenamic acid.
* **Hepatic Impairment:** Use with caution. Patients with severe hepatic impairment should avoid mefenamic acid.
## Contraindications
* Known hypersensitivity to mefenamic acid or other NSAIDs.
* History of bronchospasm, asthma, rhinitis, or urticaria following aspirin or other NSAID administration.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal (GI) bleeding or history of GI bleeding or perforation.
* Inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis).
* Severe heart failure.
* Pregnancy during the third trimester.
## Adverse Effects
Common adverse effects include diarrhea, nausea, vomiting, abdominal pain, and dyspepsia. Serious adverse effects include GI bleeding, ulceration, perforation, cardiovascular thrombotic events, renal impairment, hepatic impairment, and hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **ACE inhibitors, ARBs, Diuretics:** May decrease antihypertensive effect and increase risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate levels and toxicity.
## Monitoring
* Monitor for signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* Monitor for signs and symptoms of cardiovascular events (e.g., chest pain, shortness of breath).
* Monitor renal function (BUN, creatinine) and liver function (LFTs), especially in patients with pre-existing impairment or those on long-term therapy.
* Monitor for signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only.
* It should be taken with food or milk to minimize GI upset.
* Due to the risk of diarrhea, it is particularly important to monitor hydration status in patients receiving mefenamic acid.
**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for current prescribing information. Always consult the official product monograph or reliable drug information resources for the most up-to-date and complete prescribing guidance.
