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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the anthranilic acid derivative class. It possesses analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Mild to moderate pain, particularly associated with:
* Menstrual pain (dysmenorrhea)
* Headache
* Dental pain
* Musculoskeletal pain
## Adult Dosing
* **Pain:** 500 mg every 6 to 8 hours as needed.
* **Maximum Daily Dose:** 1500 mg. Dosing beyond 7 days is not recommended due to potential toxicity.
## Pediatric Dosing
* Mefenamic acid is generally **not recommended** for children under 14 years of age due to lack of established safety and efficacy data in this population.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe renal impairment. Monitor renal function closely.
* **Hepatic Impairment:** Use with caution. Monitor liver function tests.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of gastrointestinal (GI) bleeding or perforation related to previous NSAID use.
* Active peptic ulceration or history of recurrent peptic ulceration.
* Severe heart failure.
* Severe renal impairment (CrCl < 30 mL/min).
* Severe hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation.
* **Serious:**
* Gastrointestinal: GI bleeding, ulceration, perforation.
* Cardiovascular: Increased risk of myocardial infarction and stroke (especially with prolonged use or in patients with risk factors).
* Renal: Renal failure, interstitial nephritis, papillary necrosis.
* Hepatic: Hepatotoxicity, elevated liver enzymes.
* Hematologic: Anemia, thrombocytopenia, leukopenia.
* Hypersensitivity: Rash, 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.
* **Other NSAIDs and Salicylates:** Increased risk of GI toxicity and additive effects.
* **ACE Inhibitors and ARBs:** Reduced antihypertensive effect; increased risk of renal impairment.
* **Diuretics:** Reduced diuretic effect; increased risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* **GI Symptoms:** Monitor for signs and symptoms of GI bleeding (e.g., black stools, hematemesis).
* **Renal Function:** Monitor serum creatinine and BUN, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic Function:** Monitor liver function tests (AST, ALT) periodically.
* **Blood Pressure:** Monitor blood pressure, especially in patients with hypertension.
* **Bleeding:** Monitor for signs of bleeding, particularly in patients on concomitant anticoagulants or antiplatelets.
## Clinical Pearls
* Mefenamic acid is generally intended for short-term use only.
* Administer with food or milk to minimize GI upset.
* Avoid concomitant use with other NSAIDs.
* Educate patients about the risks of GI bleeding and cardiovascular events.
* Dosing for dysmenorrhea should typically begin with the onset of pain and menstrual bleeding and continue for the duration of the pain.
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*This information is intended for healthcare professionals. Always consult the current prescribing information and relevant literature for complete details and to ensure patient safety. Dosing and indications may vary based on local protocols and individual patient factors.*
