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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) from the fenamate class. It works 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: 1500 mg daily for short-term use (up to 7 days).
* **Dysmenorrhea:** 500 mg every 6 hours, starting with the onset of pain or bleeding and continuing for the duration of dysmenorrhea symptoms.
## Pediatric Dosing
* **Pain and Dysmenorrhea:** Generally not recommended for children under 14 years of age due to lack of established safety and efficacy. Dosing in younger children, if considered, requires careful clinical judgment and should be based on expert consensus or local protocol, often with a starting dose of 6.5 mg/kg every 6 hours.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in patients with moderate renal impairment. Avoid in severe renal impairment.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in patients with mild to moderate hepatic impairment. Avoid in severe hepatic impairment.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* History of bronchospasm, asthma, rhinitis, or urticaria induced by aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain, dyspepsia), dizziness, headache, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal impairment; hepatic dysfunction; cardiovascular thrombotic events; anaphylaxis; 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 the risk of GI bleeding.
* **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect and increased risk of renal impairment.
* **Lithium, Methotrexate:** Increased serum levels and toxicity.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
## Monitoring
* **Renal function:** Baseline and periodic monitoring of serum creatinine and BUN, especially in elderly patients or those with pre-existing renal disease.
* **Hepatic function:** Baseline and periodic monitoring of LFTs.
* **Gastrointestinal symptoms:** Monitor for signs and symptoms of bleeding or ulceration.
* **Blood pressure:** Monitor for potential increases.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Should be used for the shortest duration necessary to control symptoms.
* Long-term safety and efficacy are not established.
* Avoid concomitant use with other NSAIDs.
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***Disclaimer:** This information is intended for healthcare professionals and does not replace the need to consult the official prescribing information for mefenamic acid or other relevant clinical resources. Always verify current dosing, safety, and indications before prescribing.*
