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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the anthranilic acid derivative class. It exhibits 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.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, typically starting with the onset of pain or bleeding and continuing for the duration of symptoms, not to exceed 7 days per menstrual cycle.
* **Maximum Dose:** Not to exceed 1500 mg in 24 hours.
## Pediatric Dosing
Mefenamic acid is generally **not recommended** for pediatric patients. Safety and efficacy have not been established.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Consider dose reduction in patients with mild to moderate renal impairment. Avoid use in severe renal impairment.
* **Hepatic Impairment:** Use with caution. Monitor liver function tests. Avoid use in severe hepatic impairment.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of bronchospasm, 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: Diarrhea, nausea, vomiting, abdominal pain, headache, dizziness.
Serious: Gastrointestinal bleeding, ulceration, perforation, myocardial infarction, stroke, renal failure, hepatic failure, hypersensitivity reactions, Stevens-Johnson syndrome, toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs):** Increased risk of gastrointestinal bleeding.
* **Lithium:** Increased lithium levels and potential toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
* **Other NSAIDs/Aspirin:** Increased risk of adverse effects, particularly gastrointestinal.
* **Diuretics/ACE Inhibitors/ARBs:** Decreased antihypertensive effect and increased risk of renal dysfunction.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Renal function (serum creatinine, BUN).
* Liver function (ALT, AST).
* Blood pressure.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Due to the risk of diarrhea, monitor for dehydration and electrolyte imbalances.
* Limit duration of use to the shortest effective period.
* Consider alternatives for patients with a history of peptic ulcer disease or gastrointestinal bleeding.
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*This information is intended for clinical pharmacy use only. Please consult the most current prescribing information and relevant clinical guidelines before making any therapeutic decisions.*
