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# Mefenamic Acid
## Overview
Mefenamic acid is a non-steroidal anti-inflammatory drug (NSAID) used for short-term relief of mild to moderate pain. It works by inhibiting cyclooxygenase (COX) enzymes, which reduces the production of prostaglandins.
## Primary Indications
* Short-term treatment of mild to moderate pain, including menstrual pain (dysmenorrhea).
* Rheumatoid arthritis (adjunctive therapy).
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Do not exceed 1330 mg in 24 hours (or 1000 mg in 24 hours for extended-release formulations).
* **Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed.
* **Rheumatoid Arthritis:** 500 mg three times daily.
## Pediatric Dosing
Mefenamic acid is generally **not recommended** for children under 14 years of age due to lack of established safety and efficacy data for this age group. Specific pediatric dosing is not well-established.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dosage reduction may be necessary in severe renal impairment, but specific guidelines are not well-defined.
* **Hepatic Impairment:** Use with caution. Monitor liver function closely. Dosage reduction may be necessary in severe hepatic impairment.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of NSAID-induced bronchospasm, urticaria, or allergic rhinitis.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal bleeding or history of recurrent gastrointestinal bleeding.
* Severe heart failure, severe renal impairment, severe hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, dizziness, headache.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation, renal failure, hepatic failure, myocardial infarction, stroke, hypersensitivity reactions, Stevens-Johnson syndrome, toxic epidermal necrolysis.
## 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.
* **Other NSAIDs:** Increased risk of adverse effects.
* **ACE inhibitors, ARBs, beta-blockers:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Lithium, Methotrexate:** Increased serum concentrations and toxicity.
* **Diuretics:** May reduce diuretic effect and increase risk of renal impairment.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor renal and hepatic function, especially in patients with pre-existing impairment or those on long-term therapy.
* Monitor blood pressure.
* Assess for signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only.
* Administer with food or milk to minimize gastrointestinal upset.
* Discontinue immediately if gastrointestinal bleeding or signs of hypersensitivity occur.
* Avoid concurrent use with other NSAIDs.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols for definitive guidance.
