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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. It works by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Pain associated with menstruation (dysmenorrhea)
* Mild to moderate pain
## Adult Dosing
* **Initial dose:** 500 mg orally.
* **Subsequent doses:** 250 mg orally every 6 hours as needed.
* **Maximum daily dose:** 750 mg in the first 24 hours, then 500 mg every 6 hours thereafter.
* **Duration of therapy:** Not recommended for use longer than 7 days.
## Pediatric Dosing
Mefenamic acid is generally not recommended for use in children under 14 years of age due to limited data and potential risks.
## Dose Adjustments
No specific dose adjustments are typically required for hepatic or renal impairment, but caution is advised. Mefenamic acid is an NSAID and carries similar risks. Its use in patients with severe renal or hepatic impairment should be carefully considered.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of asthma, urticaria, or other allergic-type reactions after taking aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease.
* Renal or hepatic insufficiency.
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include diarrhea, nausea, vomiting, abdominal pain, and gastrointestinal upset. 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.
* **Other NSAIDs and salicylates:** Increased risk of gastrointestinal adverse effects.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **ACE inhibitors, angiotensin II receptor blockers, diuretics:** Reduced antihypertensive effect and increased risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate levels and toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor renal and hepatic function, especially with prolonged use or in patients with pre-existing impairment.
* Monitor blood pressure.
* Monitor for signs of cardiovascular events.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Due to its relatively short half-life and potential for gastrointestinal side effects, it is generally used for short-term pain management.
* The risk of serious cardiovascular thrombotic events, myocardial infarction, and stroke may increase with use, particularly at higher doses and with longer duration of treatment.
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*This information is intended for healthcare professionals. Always verify current prescribing information and consult with a qualified healthcare provider for any medical advice or treatment decisions.*
