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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term treatment of mild to moderate pain, including menstrual pain.
## Primary Indications
* Mild to moderate pain
* Primary dysmenorrhea
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Primary Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed.
* **Maximum daily dose:** 1250 mg.
* Treatment duration should not exceed 7 days.
## Pediatric Dosing
* Mefenamic acid is generally **not recommended** for use in children under 14 years of age for pain management due to a lack of established dosing and safety data.
* For specific indications like Kawasaki disease, consult pediatric guidelines for alternative agents and doses.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose adjustment may be necessary based on the degree of impairment and patient response. Avoid in severe renal impairment.
* **Hepatic Impairment:** Use with caution. Monitor liver function closely. Avoid in severe hepatic impairment.
## 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.
* Known inflammatory bowel disease.
* Severe renal or hepatic impairment.
* Severe heart failure.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, rash, dizziness, headache.
* **Serious:** Gastrointestinal 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. Monitor INR closely.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **ACE inhibitors, ARBs, Beta-blockers:** Reduced antihypertensive effect, increased risk of renal impairment.
* **Diuretics:** Reduced diuretic effect, increased risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* **Renal function:** Baseline and periodically, especially in patients with risk factors for renal impairment.
* **Hepatic function:** Baseline and periodically, especially in patients with liver disease.
* **Gastrointestinal symptoms:** Monitor for signs of bleeding or ulceration.
* **Blood pressure:** Especially in patients with hypertension.
* **Signs of hypersensitivity reactions.**
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Due to potential CNS effects, caution patients about driving or operating machinery.
* Limit use to the shortest duration necessary to control symptoms.
* Consider the risks of cardiovascular and gastrointestinal events associated with NSAID use.
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**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for clinical judgment. Always consult the most current prescribing information and relevant guidelines before making therapeutic decisions.
