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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term symptomatic treatment of mild to moderate pain. It is also used for the management of primary dysmenorrhea.
## Primary Indications
* Pain (mild to moderate)
* Primary dysmenorrhea
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Maximum daily dose: 2000 mg.
* **Primary Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed. Duration of treatment typically 2 to 3 days. Maximum daily dose: 1500 mg.
## Pediatric Dosing
Mefenamic acid is not generally recommended for children under 14 years of age due to a lack of established dosing and safety data. Specific pediatric dosing may be available through local protocols, but this should be carefully reviewed.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe renal impairment.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe hepatic impairment.
## Contraindications
* Hypersensitivity to mefenamic acid, other NSAIDs, or aspirin.
* History of bronchospasm, 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 (GI) bleeding or history of recurrent GI ulceration/bleeding.
* Severe renal or hepatic impairment.
* Severe heart failure.
* Pregnancy (third trimester).
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, headache, dizziness.
* **Serious:**
* **GI:** GI bleeding, ulceration, perforation.
* **Cardiovascular:** Increased risk of myocardial infarction, stroke, hypertension, heart failure.
* **Renal:** Renal papillary necrosis, interstitial nephritis, glomerulonephritis, renal failure.
* **Hepatic:** Elevated liver enzymes, hepatitis, jaundice.
* **Hypersensitivity:** Rash, angioedema, anaphylaxis, Stevens-Johnson syndrome, toxic epidermal necrolysis.
* **Hematologic:** Anemia, leukopenia, thrombocytopenia.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Lithium:** Increased lithium levels, potential for toxicity.
* **Methotrexate:** Increased methotrexate levels and toxicity.
* **Diuretics and Antihypertensives:** Reduced efficacy; increased risk of renal impairment.
* **Other NSAIDs/Aspirin:** Increased risk of adverse effects, particularly GI bleeding.
## Monitoring
* **GI Bleeding:** Monitor for signs and symptoms (e.g., melena, hematemesis, abdominal pain).
* **Renal Function:** Monitor serum creatinine and BUN, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic Function:** Monitor liver enzymes, especially in patients with pre-existing liver disease.
* **Blood Pressure:** Monitor for hypertension.
* **Cardiovascular Risk:** Assess patient's cardiovascular risk factors.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize GI upset.
* Due to the risk of GI bleeding, it should be used for the shortest duration necessary and at the lowest effective dose.
* Patients with asthma, especially aspirin-sensitive asthma, should use this medication with extreme caution.
* Use in elderly patients requires careful consideration due to increased risk of adverse effects.
**Disclaimer:** This information is intended for clinical use and does not substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines before making treatment decisions.
