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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 works by inhibiting prostaglandin synthesis.
## Primary Indications
* Mild to moderate pain, including menstrual pain (dysmenorrhea).
* Pain associated with inflammatory conditions.
## Adult Dosing
* **Pain:** 500 mg every 4 to 6 hours as needed.
* **Dysmenorrhea:** 500 mg every 4 to 6 hours as needed, starting at the onset of pain or bleeding.
* **Maximum Dose:** 1500 mg per day. Treatment duration should not exceed 7 days.
## Pediatric Dosing
* **Generally not recommended for children under 14 years of age.**
* Safety and efficacy in pediatric patients have not been established.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Data is limited, but dose reduction may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. Data is limited, but dose reduction may be considered in severe impairment.
* **Elderly:** Increased risk of adverse effects; use lower doses and monitor closely.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* 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 bleeding or ulceration.
* Severe renal or hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, headache, dizziness, rash, pruritus.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal failure; hepatic failure; hypersensitivity reactions; Stevens-Johnson syndrome/toxic epidermal necrolysis; hematologic effects.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs):** Increased risk of gastrointestinal bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of adverse effects, particularly gastrointestinal.
* **ACE inhibitors, Angiotensin II Receptor Blockers (ARBs), Diuretics:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Lithium:** May increase lithium levels and toxicity.
* **Methotrexate:** May increase methotrexate levels and toxicity.
## Monitoring
* **Renal function:** Baseline and periodically during treatment, especially in elderly patients or those with pre-existing renal disease.
* **Hepatic function:** Baseline and periodically during treatment.
* **Blood pressure:** Especially in patients treated for hypertension.
* **Signs and symptoms of gastrointestinal bleeding:** Such as melena, hematemesis, or unexplained abdominal pain.
* **Signs and symptoms of cardiovascular events.**
## Clinical Pearls
* Mefenamic acid is generally recommended for short-term use only due to the increased risk of serious adverse effects with prolonged use.
* Administer with food or milk to reduce gastrointestinal upset.
* Avoid concomitant use with other NSAIDs.
* Patients with a history of cardiovascular disease or risk factors should use mefenamic acid with caution.
* Discontinue use immediately if signs of hypersensitivity, gastrointestinal bleeding, or other serious adverse events occur.
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*Disclaimer: This information is for educational purposes only and does not substitute for professional medical advice. Always verify current prescribing information with the official drug product labeling or a reliable drug information resource before making any clinical decisions.*
