Please check your internet connection and try again.
# Mefenamic acid
## Overview
Mefenamic acid is an anthranilic acid-derivative nonsteroidal anti-inflammatory drug (NSAID). It exerts anti-inflammatory, analgesic, and antipyretic effects primarily through the inhibition of cyclooxygenase (COX-1 and COX-2) enzymes, reducing prostaglandin synthesis.
## Primary Indications
* Treatment of mild to moderate pain.
* Primary dysmenorrhea.
## Adult Dosing
* **Initial Dose:** 500 mg orally as a loading dose.
* **Maintenance:** 250 mg orally every 6 hours as needed.
* **Duration:** Should not exceed 7 days of continuous therapy.
## Pediatric Dosing
* **Adolescents (≥14 years):** Same as adult dosing (500 mg initial, followed by 250 mg q6h prn).
* **Children (<14 years):** Safety and efficacy have not been established. Use is generally not recommended.
## Dose Adjustments
* **Renal Impairment:** Avoid or exercise extreme caution in patients with severe renal impairment (CrCl <30 mL/min).
* **Hepatic Impairment:** Use with caution; monitor for signs of liver dysfunction. Dose reduction may be necessary.
* **Geriatric:** Use the lowest effective dose for the shortest duration due to increased risk of GI bleeding and renal complications.
## Contraindications
* Known hypersensitivity to mefenamic acid or aspirin/NSAIDs.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Active peptic ulceration or inflammatory bowel disease.
* Peri-operative pain management in the setting of coronary artery bypass graft (CABG) surgery.
* Severe renal or hepatic impairment.
## Adverse Effects
* **Common:** Abdominal pain, nausea, diarrhea, vomiting, dyspepsia, dizziness, headache.
* **Serious:** Cardiovascular events (MI, stroke), gastrointestinal bleeding/ulceration, renal impairment/failure, fluid retention, hypertension, hepatotoxicity, and serious skin reactions (e.g., Stevens-Johnson Syndrome).
## Key Drug Interactions
* **Anticoagulants (e.g., Warfarin):** Increased risk of bleeding.
* **Antiplatelet Agents/SSRIs:** Increased risk of GI bleeding.
* **Antihypertensives (ACE inhibitors, Beta-blockers, Diuretics):** Reduced efficacy of antihypertensive therapy; risk of renal toxicity.
* **Lithium/Methotrexate:** May increase serum concentrations and toxicity risk.
* **Other NSAIDs/Corticosteroids:** Increased risk of GI toxicity.
## Monitoring
* **Baseline/Periodic:** Renal function (creatinine, BUN), liver function tests, complete blood count (if long-term/chronic), and blood pressure.
* **Clinical:** Monitor for signs of GI bleeding (melena, hematemesis), edema, or cardiovascular symptoms.
## Clinical Pearls
* **GI Protection:** Administer with food or milk to decrease gastric irritation.
* **Duration:** The 7-day limit is strict to minimize cumulative risk of serious adverse effects, particularly diarrhea, which is more common with this specific NSAID.
* **Cross-reactivity:** Patients allergic to aspirin may show cross-sensitivity to mefenamic acid.
* **Pregnancy:** Avoid in late pregnancy (third trimester) due to risk of premature closure of the ductus arteriosus.
***
**Educational Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Always verify current prescribing information, institutional protocols, and patient-specific factors via authoritative clinical resources or a formulary service before making prescribing or dosing decisions.
