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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, particularly menstrual pain.
## Primary Indications
* Short-term management of mild to moderate pain, especially dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed.
* **Dysmenorrhea:** 500 mg orally every 6 hours, starting at the onset of pain or bleeding, whichever comes first. Treatment should not exceed 6 days per month.
* **Maximum dose:** Do not exceed 1500 mg in a 24-hour period. The duration of treatment should be limited to 7 days.
## Pediatric Dosing
* Mefenamic acid is generally **not recommended** for children under 14 years of age due to limited data and potential risks. Some sources suggest use in children ≥14 years at adult doses.
## Dose Adjustments
* No specific dose adjustments are typically required for renal or hepatic impairment, however, caution is advised due to potential for renal and hepatic toxicity with NSAIDs. Use the lowest effective dose for the shortest duration.
## 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:** Diarrhea, nausea, vomiting, abdominal pain, dyspepsia, constipation, dizziness, rash.
* **Serious:** Cardiovascular thrombotic events (MI, stroke), GI bleeding, ulceration, perforation, renal papillary necrosis, acute kidney injury, hepatic toxicity, anaphylaxis, 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.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **Other NSAIDs/Aspirin:** Increased risk of GI toxicity and additive pharmacologic effects.
* **ACE inhibitors/ARBs/Diuretics:** May diminish antihypertensive effect and increase risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* Monitor renal function (e.g., serum creatinine, BUN) especially in patients with risk factors.
* Monitor liver function (e.g., ALT, AST) especially in patients with pre-existing liver disease.
* Monitor blood pressure.
## Clinical Pearls
* Administer with food or milk to minimize GI upset.
* Use for the shortest duration necessary.
* Consider the risk of cardiovascular and GI events with NSAID use.
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***Disclaimer:** This information is intended for clinical use and does not replace professional judgment. Always consult the most current prescribing information and relevant guidelines before making clinical decisions.*
