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# Mefenamic Acid
## Overview
Mefenamic acid is a non-steroidal anti-inflammatory drug (NSAID) used for the short-term relief of pain, particularly menstrual pain (dysmenorrhea) and mild to moderate pain from other causes. It works by inhibiting 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 as needed, initiated at the onset of pain and bleeding.
* **Maximum Dose:** Not to exceed 1500 mg per day. Treatment duration should generally be limited to 7 days.
## Pediatric Dosing
* **Children 14 years and older:** Dosing is the same as adults.
* **Children under 14 years:** Mefenamic acid is generally not recommended. Safety and efficacy in this population have not been established.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment, but specific recommendations are lacking.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe impairment, but specific recommendations are lacking.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* History of bronchospasm, asthma, rhinitis, or urticaria following aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal bleeding or a history of recurrent gastrointestinal bleeding/ulceration.
* Severe heart failure.
* Severe renal impairment.
* Severe hepatic impairment.
* Pregnancy, especially during the third trimester.
## Adverse Effects
Common adverse effects include nausea, vomiting, diarrhea, abdominal pain, and constipation. Serious adverse effects can include gastrointestinal bleeding, ulceration, perforation, cardiovascular thrombotic events (MI, stroke), renal toxicity, hepatic toxicity, hypersensitivity reactions, and fluid retention/edema.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal adverse effects.
* **SSRIs/SNRIs:** Increased risk of gastrointestinal bleeding.
* **Diuretics and Antihypertensives:** May reduce efficacy and increase risk of renal toxicity.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Assess for cardiovascular risk factors and monitor for signs of cardiovascular events.
* Monitor renal and hepatic function, especially in patients with pre-existing impairment or those on long-term therapy.
* Monitor for signs of hypersensitivity reactions.
## Clinical Pearls
* Due to the risk of gastrointestinal toxicity, mefenamic acid should be taken with food or milk.
* It is indicated for short-term use only.
* The effectiveness in patients with inflammatory arthropathies is less established compared to other NSAIDs.
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*Disclaimer: This information is for educational purposes only and does not substitute professional medical advice. Always consult with a qualified healthcare provider to determine the appropriateness of any medication or treatment. Verify current prescribing information and guidelines before initiating or modifying therapy.*
