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 inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis.
## Primary Indications
* Short-term relief of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Maximum: 1500 mg/day (or up to 2000 mg/day in some sources for short-term use, but typically 1500 mg is preferred).
* **Dysmenorrhea:** 500 mg every 6 hours, starting with the onset of pain or bleeding and continuing for the duration of symptoms (usually 2-3 days). Maximum: 1500 mg/day.
## Pediatric Dosing
* Generally not recommended for children under 14 years of age due to limited data and potential for adverse effects. Some sources suggest 6.5 mg/kg every 6 hours for children >6 months, but this is less established and requires careful consideration.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Avoid in severe renal impairment.
* **Hepatic Impairment:** Use with caution. Avoid in severe hepatic impairment.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of bronchospasm, asthma, rhinitis, or urticaria induced by aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease (active or history).
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dizziness, drowsiness.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal toxicity (including interstitial nephritis, papillary necrosis); hepatic toxicity; cardiovascular thrombotic events (MI, stroke); hypersensitivity reactions; exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **ACE inhibitors, ARBs, Diuretics:** Increased risk of renal impairment; reduced antihypertensive effect.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* Signs and symptoms of GI bleeding or ulceration.
* Renal function (BUN, creatinine) especially in patients with pre-existing renal disease or those on concomitant nephrotoxic agents.
* Liver function tests (ALT, AST) especially with long-term use or in patients with hepatic impairment.
* Blood pressure.
## Clinical Pearls
* Should be taken with food or milk to minimize GI upset.
* Shortest effective duration of treatment is recommended due to risks of GI, renal, and cardiovascular events.
* Consider patient's risk factors for GI bleeding (age, history of ulcers, concomitant medications) before prescribing.
***
**Disclaimer:** This information is intended for healthcare professionals. It is essential to consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions. Dosing and safety can vary based on individual patient factors and local protocols.
