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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.
## Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Do not exceed 1330 mg in a 24-hour period, including the initial loading dose.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, starting at the onset of pain and bleeding. Treatment duration should not exceed 6 days per month.
## Pediatric Dosing
Mefenamic acid is generally not recommended for use in children under 12 years of age due to lack of established safety and efficacy data.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustments are established, but renal function should be monitored closely.
* **Hepatic Impairment:** Use with caution. No specific dose adjustments are established, but liver function should be monitored closely.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, 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.
* Inflammatory bowel disease.
* Severe heart failure, renal impairment, or hepatic impairment.
## Adverse Effects
* **Common:** Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), dizziness, drowsiness, headache.
* **Serious:**
* **Cardiovascular:** Increased risk of myocardial infarction, stroke, and heart failure.
* **Gastrointestinal:** Serious GI bleeding, ulceration, and perforation.
* **Renal:** Acute kidney injury, interstitial nephritis.
* **Hepatic:** Hepatotoxicity.
* **Hematologic:** Anemia.
* **Dermatologic:** 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.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of bleeding.
* **Diuretics and Antihypertensives:** May reduce their efficacy and increase risk of renal toxicity.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* **Baseline and periodic monitoring of renal function (BUN, creatinine).**
* **Baseline and periodic monitoring of liver function tests (ALT, AST).**
* **Monitor for signs and symptoms of GI bleeding (e.g., melena, hematemesis).**
* **Monitor for signs and symptoms of cardiovascular events (e.g., chest pain, shortness of breath).**
* **Monitor for signs of hypersensitivity reactions.**
## Clinical Pearls
* Mefenamic acid is intended for short-term use only.
* Administer with food or milk to minimize gastrointestinal upset.
* Lowest effective dose for the shortest duration should be used.
* Due to potential adverse effects, particularly GI and cardiovascular risks, alternative analgesics should be considered, especially for patients with pre-existing risk factors.
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*Disclaimer: This information is intended for healthcare professionals and does not replace the need to consult the official prescribing information and other relevant literature before making clinical decisions. Always verify current dosing and safety information with the most up-to-date drug product labeling.*
