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# Mefenamic Acid ## Overview Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class, used for the short-term management of mild to moderate pain. ## Primary Indications * Pain relief, including menstrual pain (dysmenorrhea). * Management of pain associated with osteoarthritis and rheumatoid arthritis. ## Adult Dosing * **Pain:** 500 mg every 6 hours as needed. * **Dysmenorrhea:** 500 mg every 6 hours as needed, starting at the onset of pain and bleeding. * **Maximum daily dose:** 1500 mg. Duration of treatment should generally not exceed 7 days. ## Pediatric Dosing * **Established pediatric dosing is not widely available.** Use in pediatric patients should be based on clinical judgment and specific guidelines. Some sources suggest doses of 6.5 mg/kg every 6 hours, with a maximum of 500 mg per dose. ## Dose Adjustments * **Renal Impairment:** Use with caution. No specific dose adjustment guidelines are established, but reduced doses may be considered in severe impairment. * **Hepatic Impairment:** Use with caution. No specific dose adjustment guidelines are established, but reduced doses may be considered in severe impairment. * **Geriatric:** Use with caution, as NSAIDs can increase the risk of gastrointestinal and cardiovascular events. Consider a lower starting dose and longer monitoring. ## 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 bleeding or ulceration. * Severe renal or hepatic impairment. * Late pregnancy (third trimester). ## Adverse Effects * **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dizziness, rash. * **Serious:** Gastrointestinal bleeding, perforation, ulceration; cardiovascular thrombotic events (myocardial infarction, stroke); renal failure; hepatic failure; hypersensitivity reactions; Stevens-Johnson syndrome; toxic epidermal necrolysis. ## Key Drug Interactions * **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. * **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding. * **Selective Serotonin Reuptake Inhibitors (SSRIs):** Increased risk of gastrointestinal bleeding. * **Diuretics, ACE inhibitors, ARBs:** May reduce antihypertensive effect and increase risk of renal impairment. * **Lithium:** Increased lithium levels. * **Methotrexate:** Increased methotrexate toxicity. ## Monitoring * Signs and symptoms of gastrointestinal bleeding or ulceration. * Renal function (creatinine, BUN). * Hepatic function (LFTs), especially with prolonged use. * Blood pressure. * Signs of cardiovascular events. ## Clinical Pearls * Mefenamic acid is typically recommended for short-term use only due to the increased risk of adverse events with prolonged exposure. * Administer with food or milk to minimize gastrointestinal upset. * Avoid concomitant use with other NSAIDs. * Patients with a history of peptic ulcer disease should use with extreme caution or avoid. *** *Disclaimer: This information is for educational purposes only and does not constitute prescribing advice. Always consult the most current prescribing information and local institutional protocols before making any treatment decisions.*