Please check your internet connection and try again.
# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed.
* **Dysmenorrhea:** 500 mg orally every 6 hours, starting at the onset of pain and bleeding, and continuing for the duration of symptoms, up to 5 days.
The maximum daily dose should not exceed 1500 mg. Treatment duration should be limited to 7 days for pain.
## Pediatric Dosing
Dosing in pediatric patients is not well-established and should be based on weight and clinical judgment, often extrapolated from adult data. Refer to specific pediatric guidelines or consult a pediatric specialist.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe renal impairment. Data is limited.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe hepatic impairment. Data is limited.
* **Elderly:** Elderly patients may be more susceptible to adverse effects, particularly gastrointestinal bleeding and renal toxicity. Consider lower doses.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* History of asthma, urticaria, or allergic-type reactions after aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal bleeding or ulceration.
* Severe heart failure.
* Severe renal impairment.
* Severe hepatic impairment.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, headache, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal toxicity (including interstitial nephritis, papillary necrosis); cardiovascular thrombotic events (myocardial infarction, stroke); hypersensitivity reactions; Stevens-Johnson syndrome; toxic epidermal necrolysis; hepatic dysfunction.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of gastrointestinal bleeding.
* **Lithium:** Increased lithium levels and toxicity. Monitor lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
* **Diuretics and Antihypertensives:** Reduced antihypertensive efficacy; increased risk of renal toxicity.
* **Other NSAIDs (including aspirin):** Increased risk of adverse effects, particularly gastrointestinal.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Assess renal function (serum creatinine, BUN) periodically, especially in patients with pre-existing renal disease or those on concurrent nephrotoxic agents.
* Monitor liver function tests periodically, especially with long-term use.
* Assess for signs of cardiovascular events.
## Clinical Pearls
* Mefenamic acid has a short half-life and is typically used for short-term pain management or dysmenorrhea.
* It should be taken with food or milk to minimize gastrointestinal upset.
* Due to its short duration of action, it is generally not suitable for chronic inflammatory conditions.
* Consider the risks of NSAIDs in patients with underlying cardiovascular disease, renal impairment, or a history of gastrointestinal issues.
***
**Disclaimer:** This information is intended for healthcare professionals. It is essential to consult the most current prescribing information and relevant clinical guidelines for definitive guidance. Dosing and safety information can vary.
