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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis.
## Primary Indications
* **Pain:** Management of mild to moderate pain, including dysmenorrhea.
* **Inflammation:** Relief of inflammatory symptoms.
## Adult Dosing
* **Pain/Dysmenorrhea:** 500 mg orally every 6 hours as needed.
* **Maximum Daily Dose:** 1500 mg.
* **Duration:** Generally for short-term use only.
## Pediatric Dosing
* **Generally not recommended in children under 14 years of age.** Efficacy and safety in this population are not well-established.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Reduce dose or frequency if severe impairment exists.
* **Hepatic Impairment:** Use with caution. Monitor liver function closely.
## Contraindications
* Hypersensitivity to mefenamic acid, other NSAIDs, or any component of the formulation.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Peri-operative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active peptic ulceration or GI bleeding.
* Severe renal or hepatic impairment.
* Last trimester of pregnancy.
## Adverse Effects
* **Gastrointestinal:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, GI bleeding, ulceration.
* **Central Nervous System:** Dizziness, drowsiness, headache.
* **Renal:** Acute kidney injury, interstitial nephritis.
* **Hepatic:** Elevated liver enzymes, hepatitis.
* **Hematologic:** Anemia, leukopenia, thrombocytopenia.
* **Hypersensitivity:** Rash, pruritus, bronchospasm.
* **Cardiovascular:** Increased risk of serious cardiovascular thrombotic events, myocardial infarction, and stroke.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of GI toxicity and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Lithium:** Increased serum lithium levels, risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
* **Diuretics and Antihypertensives:** Reduced efficacy and increased risk of renal impairment.
## Monitoring
* **GI Symptoms:** Monitor for signs and symptoms of GI bleeding or ulceration.
* **Renal Function:** Monitor BUN and creatinine, especially in patients with pre-existing renal disease.
* **Hepatic Function:** Monitor liver enzymes (ALT, AST) periodically.
* **Blood Pressure:** Monitor blood pressure, especially in patients with hypertension.
* **Cardiovascular Risk:** Assess cardiovascular risk factors.
## Clinical Pearls
* Administer with food or milk to minimize GI upset.
* Use the lowest effective dose for the shortest possible duration to minimize risks.
* Avoid concomitant use with other NSAIDs.
* Educate patients on signs and symptoms of GI bleeding and cardiovascular events.
**Disclaimer:** This information is intended for healthcare professionals. Always consult the current official prescribing information and relevant guidelines for comprehensive details before making clinical decisions.
