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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term relief of mild to moderate pain, including menstrual pain.
## Primary Indications
* Relief of mild to moderate pain.
* Primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Treatment should not exceed 7 days.
* **Primary Dysmenorrhea:** 500 mg every 6 hours starting at the onset of pain and bleeding. Treatment should not exceed 7 days.
## Pediatric Dosing
* Mefenamic acid is generally not recommended for children under 14 years of age due to limited data and potential for adverse effects.
* For children aged 14 years and older, the adult dosing recommendations apply.
## Dose Adjustments
* No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised due to potential for NSAID-induced nephrotoxicity and hepatotoxicity. Monitor closely.
## 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 (GI) bleeding or history of recurrent GI ulceration or hemorrhage.
* Severe renal impairment.
* Severe hepatic impairment.
* Severe heart failure.
* Pregnancy, especially in the third trimester.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, headache, dizziness, rash.
* **Serious:** GI bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal failure; hepatic failure; hypersensitivity reactions; Stevens-Johnson syndrome; toxic epidermal necrolysis; exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Diuretics, ACE inhibitors, ARBs:** May decrease antihypertensive effect and increase risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate levels and toxicity.
## Monitoring
* Signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* Renal function (BUN, creatinine).
* Liver function tests (AST, ALT).
* Blood pressure.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize GI upset.
* It is intended for short-term use only. Prolonged use increases the risk of serious adverse effects.
* Use the lowest effective dose for the shortest duration necessary.
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**Disclaimer:** This information is intended for healthcare professionals and does not substitute for clinical judgment. Always consult the most current prescribing information and institutional protocols.
