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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It possesses analgesic, anti-inflammatory, and antipyretic properties through the inhibition of cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Maximum daily dose is 1500 mg. Therapy should not exceed 7 days.
* **Dysmenorrhea:** 500 mg every 6 hours, starting with the onset of bleeding and associated symptoms. Maximum daily dose is 1500 mg. Therapy should not exceed 7 days.
## Pediatric Dosing
Mefenamic acid is **not recommended for use in children under 14 years of age** for pain management due to lack of established safety and efficacy.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustment is established, but dose reduction may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. No specific dose adjustment is established, but dose reduction may be considered in severe impairment.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* History of bronchospasm, asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
## Adverse Effects
Common adverse effects include: nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, rash, and dizziness.
Serious adverse effects may include: gastrointestinal bleeding, ulceration, perforation, cardiovascular thrombotic events, myocardial infarction, stroke, renal failure, hepatic failure, and hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Aspirin:** Concurrent use may increase the risk of GI adverse effects and decrease the cardioprotective effect of low-dose aspirin.
* **Corticosteroids:** Increased risk of GI bleeding and ulceration.
* **Diuretics:** NSAIDs may reduce the efficacy of diuretics and increase the risk of nephrotoxicity.
* **Lithium:** NSAIDs can increase serum lithium levels and risk of lithium toxicity.
* **Methotrexate:** NSAIDs may increase methotrexate levels and toxicity.
* **Selective Serotonin Reuptake Inhibitors (SSRIs):** Increased risk of GI bleeding.
## Monitoring
* **Renal function:** Monitor serum creatinine and BUN, especially in patients with risk factors for renal impairment.
* **Hepatic function:** Monitor liver enzymes, especially in patients with pre-existing liver disease.
* **Gastrointestinal symptoms:** Assess for signs and symptoms of bleeding or ulceration.
* **Blood pressure:** NSAIDs can cause new-onset hypertension or worsen existing hypertension.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Due to the potential for serious GI events, use the lowest effective dose for the shortest duration necessary.
* Discontinue if signs of rash, hypersensitivity, or severe GI symptoms occur.
* Be aware of the increased cardiovascular and gastrointestinal risks associated with NSAID use, particularly in elderly patients or those with pre-existing risk factors.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions.*
