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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) with analgesic and anti-inflammatory properties. It functions by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Relief of mild to moderate pain.
* Treatment of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 4 to 6 hours as needed. Do not exceed 1500 mg in any 24-hour period.
* **Dysmenorrhea:** 500 mg as the first dose, followed by 250 mg every 6 hours as needed. Treatment should not exceed 6 days per month.
## Pediatric Dosing
Mefenamic acid is generally **not recommended** for pediatric patients due to a lack of established safety and efficacy data.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised, and use should be minimized in patients with severe impairment.
## Contraindications
* Known 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 a history of gastrointestinal bleeding with previous NSAID use.
* Severe heart failure.
* Severe renal or hepatic impairment.
## Adverse Effects
Common adverse effects include nausea, vomiting, diarrhea, abdominal pain, headache, and dizziness. Serious adverse effects may include gastrointestinal bleeding, ulceration, perforation, cardiovascular thrombotic events, renal injury, hepatic injury, and hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal bleeding and ulceration.
* **Selective Serotonin Reuptake Inhibitors (SSRIs):** Increased risk of bleeding.
* **Other NSAIDs or Salicylates:** Increased risk of adverse effects, particularly gastrointestinal.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate levels and toxicity.
* **Diuretics and Antihypertensives:** May reduce the antihypertensive effect and increase the risk of renal toxicity.
## Monitoring
* **Gastrointestinal:** Monitor for signs and symptoms of bleeding (e.g., melena, hematemesis).
* **Renal function:** Especially in patients with pre-existing renal disease or those taking concomitant nephrotoxic agents.
* **Hepatic function:** If symptoms of liver dysfunction develop.
* **Cardiovascular risk:** Assess and manage risk factors if used long-term.
## Clinical Pearls
* Mefenamic acid should be taken with food to minimize gastrointestinal upset.
* Duration of use should be limited to the shortest effective period, generally not exceeding 7 days for pain.
* It is typically used for short-term pain relief rather than chronic inflammatory conditions.
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*This information is intended for healthcare professionals and does not replace professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions.*
