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# Mefenamic Acid
## Overview
Mefenamic acid is a non-steroidal 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 8 hours, taken with food. Duration of treatment should not exceed 7 days.
* **Dysmenorrhea:** 500 mg every 8 hours, taken with food, starting at the onset of pain and bleeding. Duration of treatment should not exceed 3 days.
* **Maximum Daily Dose:** 1500 mg.
## Pediatric Dosing
* Mefenamic acid is generally not recommended for children under 14 years of age due to limited safety and efficacy data.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary, but specific guidelines are not well-established. Monitor renal function closely.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary, but specific guidelines are not well-established. Monitor hepatic function closely.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* History of NSAID-induced bronchospasm, urticaria, or allergic-type reactions.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal bleeding or history of recurrent gastrointestinal bleeding.
* Severe heart failure.
* Severe renal impairment.
* Severe hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, headache, dizziness, rash, pruritus.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal failure; hepatic failure; hypersensitivity reactions; Stevens-Johnson syndrome/toxic epidermal necrolysis; exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of adverse effects, particularly gastrointestinal toxicity.
* **Diuretics and Antihypertensives:** May reduce antihypertensive effect and increase risk of renal toxicity.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased methotrexate levels and toxicity.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Renal function (serum creatinine, BUN) especially in patients with pre-existing renal disease or at risk.
* Hepatic function (AST, ALT) especially in patients with pre-existing hepatic disease or at risk.
* Blood pressure, particularly in patients on antihypertensive medications.
* Signs of hypersensitivity reactions.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Use the lowest effective dose for the shortest duration necessary to minimize risks.
* Advise patients to avoid concomitant use with other NSAIDs.
* Discontinue use and seek medical attention if any signs of gastrointestinal bleeding, cardiovascular events, or severe allergic reactions occur.
* Due to its short half-life, it is typically dosed every 8 hours.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines for complete details.
