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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 acts by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Mild to moderate pain, including dysmenorrhea, dental pain, and musculoskeletal pain.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Do not exceed 1500 mg in any 24-hour period for the first 7 days of treatment. After the first 7 days, the maximum daily dose should not exceed 1000 mg.
## Pediatric Dosing
* Mefenamic acid is generally not recommended for use in children under 12 years of age due to limited data and potential for adverse effects.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Reduced doses may be necessary in patients with moderate renal impairment. Avoid in severe renal impairment.
* **Hepatic Impairment:** Use with caution. Reduced doses may be necessary in patients with hepatic impairment. Avoid in severe hepatic impairment.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* History of aspirin-induced asthma, urticaria, or other allergic-type reactions.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Advanced renal disease.
* Severe hepatic impairment.
* Severe heart failure.
* Third trimester of pregnancy.
## Adverse Effects
Common: Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, headache, dizziness, rash.
Serious: Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal failure; hepatic failure; hypersensitivity reactions; bronchospasm; Stevens-Johnson syndrome/toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **ACE inhibitors/ARBs/Diuretics:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Lithium:** Increased lithium levels, potential for toxicity.
* **Methotrexate:** Increased methotrexate levels, potential for toxicity.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Renal function (BUN, creatinine) especially in elderly or those with pre-existing renal disease.
* Liver function tests (ALT, AST) especially in patients with pre-existing liver disease.
* Blood pressure.
* Signs of hypersensitivity reactions.
## Clinical Pearls
* Limit mefenamic acid use to the shortest duration necessary to control symptoms.
* Administer with food or milk to minimize gastrointestinal upset.
* Avoid concurrent use with other NSAIDs.
* Advise patients to report any signs of bleeding, including black tarry stools or vomiting blood.
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**Disclaimer:** This information is intended for clinical use and does not replace professional medical judgment. Always consult the most current prescribing information and relevant literature for comprehensive details before making any treatment decisions.
