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# Mefanamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) from the fenamate class. It works by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Primary dysmenorrhea
* Mild to moderate pain, including menstrual pain and pain associated with musculoskeletal conditions.
## Adult Dosing
* **Dysmenorrhea:** 500 mg every 4 to 6 hours as needed. Maximum daily dose: 1500 mg.
* **Pain:** 500 mg every 4 to 6 hours as needed. Maximum daily dose: 1500 mg.
* Treatment should not exceed 7 days.
## Pediatric Dosing
Mefenamic acid is generally **not recommended** for children under 14 years of age for pain or dysmenorrhea due to safety concerns and lack of established pediatric dosing guidelines.
## Dose Adjustments
No specific dose adjustments are routinely recommended for renal or hepatic impairment, but caution is advised due to potential for drug accumulation and adverse effects. Use the lowest effective dose for the shortest duration.
## 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 impairment.
* Severe hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), dizziness, drowsiness.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal toxicity (including interstitial nephritis, papillary necrosis); cardiovascular thrombotic events (myocardial infarction, stroke); hypersensitivity reactions; hepatic toxicity; hematologic effects.
## 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 adverse effects and may reduce the cardioprotective effects of low-dose aspirin.
* **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
* **Gastrointestinal:** Monitor for signs and symptoms of bleeding or ulceration.
* **Renal:** Assess renal function (serum creatinine, BUN) especially in patients with pre-existing renal disease or those on concomitant nephrotoxic drugs.
* **Hepatic:** Monitor liver function tests (LFTs) if prolonged use or signs of hepatic dysfunction.
* **Blood Pressure:** Monitor blood pressure, especially in patients with hypertension.
## Clinical Pearls
* Use the lowest effective dose for the shortest duration necessary to minimize risks.
* Administer with food or milk to reduce gastrointestinal upset.
* Caution in elderly patients, those with cardiovascular disease, hypertension, renal impairment, hepatic impairment, or a history of peptic ulcer disease.
* Discontinue at the first sign of rash, allergic reaction, or gastrointestinal bleeding.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information, institutional protocols, and relevant literature before making any clinical decisions. Dosing and recommendations may vary.
