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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term management of mild to moderate pain. It also has anti-inflammatory and antipyretic properties.
## Primary Indications
* Short-term relief of mild to moderate pain, including menstrual pain (dysmenorrhea).
## Adult Dosing
* **Initial dose:** 500 mg.
* **Subsequent doses:** 250 mg every 6 hours as needed.
* **Maximum daily dose:** 1500 mg.
* **Duration of use:** Typically recommended for no more than 7 days.
## Pediatric Dosing
* Mefenamic acid is generally not recommended for children under 14 years of age due to lack of established safety and efficacy data. However, some sources suggest **5 mg/kg per dose orally every 6 hours**, with a maximum daily dose of **250 mg**. **Consult local protocols and pediatric guidelines.**
## Dose Adjustments
* No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised, and the lowest effective dose should be used. Mefenamic acid is contraindicated in severe renal or hepatic 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.
* Active gastrointestinal (GI) bleeding or history of recurrent GI ulceration/bleeding.
* Severe heart failure, severe renal impairment, and severe hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation.
* **Serious:** GI bleeding, ulceration, perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal toxicity (acute kidney injury, interstitial nephritis); hepatic toxicity; hypersensitivity reactions; exacerbation of asthma; fluid retention and edema.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Diuretics, ACE inhibitors, Angiotensin II Receptor Blockers (ARBs):** Reduced antihypertensive effect and increased risk of renal impairment.
* **Lithium:** Increased lithium levels and risk of toxicity.
* **Methotrexate:** Increased methotrexate levels and toxicity.
## Monitoring
* Monitor for signs and symptoms of GI bleeding or ulceration (e.g., melena, hematemesis).
* Monitor renal function, especially in patients with pre-existing renal disease or those at risk.
* Monitor for signs of cardiovascular events.
* Assess for signs of hypersensitivity reactions.
## Clinical Pearls
* Administer with food or milk to minimize GI upset.
* Use for the shortest duration necessary to control symptoms.
* Consider the risk of GI bleeding and cardiovascular events, especially with prolonged use or in high-risk patients.
* Due to potential for GI and renal adverse effects, it is often considered a second-line agent compared to other NSAIDs.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant guidelines before making any clinical decisions.*
