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# Mefenamic acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It functions by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain.
* Primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Dysmenorrhea:** 500 mg every 6 hours, starting with the onset of pain or bleeding and continuing for up to 3 days if needed.
* Maximum daily dose: 1500 mg. Treatment duration should not exceed 7 days.
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age. Limited data exists for pediatric use.
## Dose Adjustments
No specific dose adjustments are typically required for hepatic or renal impairment, but caution is advised due to potential for drug accumulation and adverse effects. Monitor closely and consider dose reduction in patients with severe impairment.
## 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.
* Inflammatory bowel disease.
* Severe renal, hepatic, or cardiac impairment.
## Adverse Effects
Common adverse effects include gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), dyspepsia, and headache. Serious adverse effects include:
* Gastrointestinal bleeding, ulceration, and perforation.
* Cardiovascular thrombotic events (myocardial infarction, stroke).
* Renal toxicity (acute kidney injury).
* Hepatic toxicity.
* Hypersensitivity reactions.
* Hematologic effects (anemia, thrombocytopenia).
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of bleeding.
* **ACE inhibitors/ARBs/Diuretics:** Reduced antihypertensive efficacy and increased risk of renal toxicity.
* **Lithium:** Increased lithium levels and risk of toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Assess for cardiovascular, renal, and hepatic function, especially with prolonged use or in at-risk individuals.
* Monitor for signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only due to the risk of serious adverse events.
* Administer with food or milk to minimize gastrointestinal upset.
* Avoid concomitant use with other NSAIDs.
* Use the lowest effective dose for the shortest duration necessary.
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**Disclaimer:** This information is intended for healthcare professionals and does not replace the need for comprehensive drug information resources or professional judgment. Always consult the most current prescribing information and local protocols before making treatment decisions.
