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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It works by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed.
* **Dysmenorrhea:** 500 mg orally every 6 hours as needed, starting at the onset of pain and bleeding and continuing for the duration of dysmenorrhea.
* **Maximum Dose:** 1500 mg per day. Treatment duration should not exceed 7 days.
## Pediatric Dosing
Mefenamic acid is not generally recommended for children under 14 years of age due to a lack of established dosing and potential for adverse effects.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised, and use may be contraindicated in severe cases due to potential for renal toxicity and hepatic effects.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of NSAID-induced bronchospasm, urticaria, or allergic-type reactions.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Known or suspected intestinal obstruction or perforation.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, dizziness, headache.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal failure; hepatic dysfunction; cardiovascular thrombotic events; anaphylaxis; Stevens-Johnson syndrome; toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal bleeding and ulceration.
* **ACE inhibitors, ARBs, Diuretics:** Reduced antihypertensive effect and increased risk of renal dysfunction.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor renal function (BUN, creatinine) especially in patients with pre-existing renal disease or risk factors for renal impairment.
* Monitor liver function (AST, ALT) if prolonged use is anticipated or if liver dysfunction is suspected.
* Monitor for signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid is generally intended for short-term use only due to increased risk of GI toxicity with prolonged use.
* Administer with food or milk to minimize gastrointestinal upset.
* Effectiveness for pain relief may not be immediate; consider alternative analgesics for severe pain.
* Avoid concomitant use with other NSAIDs.
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**Disclaimer:** This information is intended for healthcare professionals. Always verify current prescribing information and consult with a pharmacist or physician before making any treatment decisions.
