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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.
## Primary Indications
* Pain (mild to moderate)
* Dysmenorrhea
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Not to exceed 7 days.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, starting at the onset of pain or bleeding, whichever occurs first.
## Pediatric Dosing
* Mefenamic acid is generally not recommended for children under 14 years of age due to a higher risk of adverse effects.
* When used in children 14 years and older, dosing is the same as adult dosing.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment.
* **Hepatic Impairment:** Use with caution. Consider dose reduction.
## 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 bleeding.
* Severe renal impairment.
* Severe hepatic impairment.
* Severe heart failure.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, rash, dizziness, headache.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal failure; hepatic failure; cardiovascular thrombotic events (myocardial infarction, stroke); 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.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Diuretics, ACE inhibitors, Angiotensin II Receptor Blockers (ARBs):** NSAIDs can reduce the antihypertensive effect and increase the risk of renal impairment.
* **Lithium:** NSAIDs can increase lithium levels.
* **Methotrexate:** NSAIDs can increase methotrexate toxicity.
* **Other NSAIDs and Aspirin:** Increased risk of GI and other adverse effects.
## Monitoring
* Signs and symptoms of GI bleeding or ulceration.
* Renal function (BUN, creatinine).
* Liver function tests (LFTs).
* Blood pressure.
* Signs of cardiovascular events.
## Clinical Pearls
* Maximum daily dose should not exceed 1500 mg.
* Duration of treatment should be limited to 7 days for pain indications.
* Administer with food or milk to minimize GI upset.
* Discontinue if any signs of hypersensitivity or severe adverse effects occur.
* Use the lowest effective dose for the shortest duration necessary to minimize risks.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols before dispensing or administering any medication.
