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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 is a fenamate derivative.
## Primary Indications
* Pain, mild to moderate
* Primary dysmenorrhea
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Treatment should not exceed 7 days.
* **Primary dysmenorrhea:** 500 mg every 6 hours as needed, starting at the onset of pain and bleeding, and continuing for the duration of the pain.
## Pediatric Dosing
* **Pain and Dysmenorrhea:** Mefenamic acid is generally not recommended for children under 14 years of age due to potential risks and lack of established efficacy and safety data. However, if used under specific expert guidance, typical dosing is 6.5 mg/kg every 6 hours. *Confirm with local pediatric protocols.*
## Dose Adjustments
No dose adjustments are typically required for renal or hepatic impairment, but caution is advised. Use the lowest effective dose.
## Contraindications
* Known 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 (active or history).
* Severe renal or hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include diarrhea, nausea, vomiting, abdominal pain, and rash. Serious adverse effects 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.
* **Corticosteroids:** Increased risk of gastrointestinal adverse effects.
* **Aspirin:** May decrease the cardioprotective effects of low-dose aspirin; concurrent use generally not recommended.
* **Other NSAIDs:** Increased risk of gastrointestinal and renal adverse effects.
* **Lithium:** Increased lithium levels.
* **ACE inhibitors, ARBs, Diuretics:** Increased risk of renal impairment.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding.
* Monitor renal and hepatic function, especially in patients with pre-existing conditions or those on long-term therapy.
* Monitor for cardiovascular risk factors.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Due to its short half-life, it is typically dosed every 6 hours.
* Maximum duration of use is typically limited to 7 days for pain indications.
* Not a first-line agent for chronic pain or inflammatory conditions.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines for definitive dosing, safety, and efficacy data.
