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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.
## Primary Indications
* Primary dysmenorrhea
* Mild to moderate pain (e.g., headache, muscle ache, dental pain)
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Primary Dysmenorrhea:** 500 mg every 6 hours as needed, typically started at the onset of bleeding and associated pain.
Maximum daily dose: 1500 mg. Therapy duration should be limited to a maximum of 7 days.
## Pediatric Dosing
Safety and efficacy in pediatric patients under 14 years of age have not been established.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment, although specific guidelines are not well-established.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe impairment, although specific guidelines are not well-established.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* 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.
* Active gastrointestinal bleeding or a history of recurrent gastrointestinal bleeding.
* Severe renal or hepatic impairment.
* Severe heart failure.
* Pregnancy in the third trimester.
## Adverse Effects
Common: Nausea, vomiting, diarrhea, abdominal pain, constipation, rash, dizziness, headache.
Serious: Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal toxicity; hepatic toxicity; hypersensitivity reactions; exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of gastrointestinal 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
* **Gastrointestinal:** Monitor for signs and symptoms of bleeding (e.g., melena, hematemesis).
* **Renal function:** Baseline and periodic monitoring of serum creatinine and BUN, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic function:** Baseline and periodic monitoring of liver enzymes, especially in patients with pre-existing liver disease.
* **Cardiovascular:** Assess for signs and symptoms of ischemic events.
* **Blood pressure:** Monitor, especially in patients with hypertension.
## Clinical Pearls
* Mefenamic acid is generally recommended for short-term use only due to the risk of serious adverse effects.
* Administer with food or milk to minimize gastrointestinal upset.
* Avoid concomitant use with other NSAIDs to reduce the risk of cumulative toxicity.
* Consider gastroprotective agents (e.g., PPIs) in patients at high risk for GI complications.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the official prescribing information and institutional guidelines for the most current and comprehensive drug details. Verify all medication orders against the patient's medical record and current clinical guidelines.*
