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# Mefenamic acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits prostaglandin synthesis. It is used for short-term relief of mild to moderate pain.
## Primary Indications
* Pain associated with menstruation (primary dysmenorrhea)
* Mild to moderate pain
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed.
* **Maximum:** Not to exceed 1000 mg in the first 12 hours of treatment, and not more than 2,000 mg in a 24-hour period of continued therapy.
## Pediatric Dosing
Mefenamic acid is **not recommended** for use in children under 14 years of age due to lack of established safety and efficacy.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose adjustments may be necessary in severe impairment.
* **Hepatic Impairment:** Use with caution. Dose adjustments may be necessary in 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.
* Inflammatory bowel disease.
* Severe renal or hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dizziness, headache.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal toxicity (including interstitial nephritis, papillary necrosis); hepatic impairment; cardiovascular thrombotic events; 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.
* **Other NSAIDs (including aspirin):** Increased risk of gastrointestinal toxicity and other adverse effects.
* **ACE inhibitors, ARBs, diuretics:** Reduced antihypertensive effect and increased risk of renal impairment.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding.
* Assess renal and hepatic function periodically, especially with long-term use or in patients with pre-existing impairment.
* Monitor for signs of hypersensitivity reactions.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Limit treatment duration to the shortest effective period, typically 7 days, due to the risk of adverse effects.
* Discontinue immediately if rash, allergic reaction, or signs of gastrointestinal bleeding occur.
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**Disclaimer:** This information is for educational purposes only and does not constitute prescribing advice. Always consult the most current prescribing information and relevant clinical guidelines before making any medication decisions.
