Please check your internet connection and try again.
# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It functions by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain, including menstrual pain (dysmenorrhea) and pain associated with rheumatoid arthritis or osteoarthritis.
* Management of heavy menstrual bleeding.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Maximum daily dose is 1500 mg. Treatment should not exceed 7 days.
* **Dysmenorrhea and Heavy Menstrual Bleeding:** 500 mg every 6 to 8 hours. Treatment should begin at the onset of bleeding and associated pain, and continue for the duration of symptoms, typically no longer than 7 days.
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age. Safety and efficacy in younger children have not been established.
## Dose Adjustments
No specific dose adjustments are required for renal or hepatic impairment. However, caution is advised in patients with pre-existing renal or hepatic disease, and the lowest effective dose should be used.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal (GI) bleeding or history of recurrent GI ulceration/bleeding.
* Severe heart failure.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, dyspepsia, constipation, headache, rash.
* **Serious:** GI bleeding, ulceration, perforation; renal toxicity (including interstitial nephritis, papillary necrosis); cardiovascular thrombotic events (MI, stroke); anaphylaxis; hepatic dysfunction; 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.
* **Aspirin:** May decrease the cardioprotective effects of low-dose aspirin.
* **Diuretics, ACE inhibitors, ARBs:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Lithium, Methotrexate:** Increased serum levels and toxicity.
## Monitoring
* Monitor for signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* Assess renal function (serum creatinine, BUN) periodically, especially in patients with risk factors.
* Monitor liver function tests (LFTs) if symptoms of hepatic dysfunction develop.
* Monitor blood pressure.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize GI upset.
* Due to the risk of diarrhea, it is generally recommended for short-term use only.
* It is not typically a first-line agent for chronic pain due to its short duration of action and potential for GI side effects.
***
*Disclaimer: This information is intended for clinical use and does not substitute for professional medical judgment. Always consult the most current prescribing information and relevant guidelines before making therapeutic decisions.*
