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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It acts by inhibiting 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: 1500 mg.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, starting at the onset of pain or bleeding.
## Pediatric Dosing
* Mefenamic acid is generally **not recommended** for use in children under 14 years of age due to limited data and potential for adverse effects.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be considered in severe impairment, though specific guidelines are lacking.
* **Hepatic Impairment:** Use with caution. Dose reduction may be considered in severe impairment, though specific guidelines are lacking.
## 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.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dizziness, headache, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal impairment; hepatic impairment; cardiovascular thrombotic events; hypersensitivity reactions; Stevens-Johnson syndrome; toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Aspirin:** May decrease the cardioprotective effect of low-dose aspirin and increase GI risk.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Diuretics and Antihypertensives:** NSAIDs can reduce their efficacy and increase risk of renal impairment.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
* **Selective Serotonin Reuptake Inhibitors (SSRIs):** Increased risk of GI bleeding.
## Monitoring
* **Renal function:** Baseline and periodically during treatment, especially in patients with risk factors.
* **Hepatic function:** Baseline and periodically during treatment, especially in patients with pre-existing liver disease.
* **Signs and symptoms of GI bleeding:** Hematemesis, melena, abdominal pain.
* **Blood pressure:** Monitor for potential increases.
## Clinical Pearls
* Administer with food or milk to minimize GI upset.
* Limit duration of use to the shortest effective period to minimize risks.
* Avoid concurrent use with other NSAIDs.
* Consider gastroprotection (e.g., PPI) for patients at high risk of GI events.
* Use the lowest effective dose for the shortest duration necessary.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines for complete details and to verify dosage and safety information before administering or prescribing this medication.*
