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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) with analgesic and anti-inflammatory properties.
## Primary Indications
* Short-term management of mild to moderate pain, including menstrual pain (dysmenorrhea) and pain associated with dental procedures.
* Management of symptoms of rheumatoid arthritis and osteoarthritis (though not typically a first-line agent).
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed.
* **Dysmenorrhea:** 500 mg orally initially, followed by 250 mg every 6 hours as needed.
* **Rheumatoid Arthritis/Osteoarthritis:** 500 mg orally 3 times daily.
* **Maximum Dose:** 1500 mg per day. Treatment duration for pain should generally not exceed 7 days.
## Pediatric Dosing
* **Age 12 years and older:** Dosing is the same as adult dosing for pain and dysmenorrhea.
* **Children under 12 years:** Mefenamic acid is generally not recommended due to limited data on safety and efficacy.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary, especially in severe impairment.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe 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.
* Active gastrointestinal bleeding or ulceration.
* Severe renal or hepatic impairment.
* Last trimester of pregnancy.
## Adverse Effects
Common: Nausea, vomiting, diarrhea, abdominal pain, constipation, dizziness, headache.
Serious: Gastrointestinal bleeding, ulceration, perforation; renal toxicity (including interstitial nephritis, papillary necrosis); hepatic toxicity; cardiovascular thrombotic events; hypersensitivity reactions (including Stevens-Johnson syndrome, toxic epidermal necrolysis); exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal bleeding.
* **SSRIs and SNRIs:** Increased risk of gastrointestinal bleeding.
* **ACE inhibitors, ARBs, diuretics:** Decreased antihypertensive effect and increased risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate levels and toxicity.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Renal function (BUN, creatinine).
* Liver function tests (ALT, AST).
* Blood pressure.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Limit duration of use to the shortest effective period due to potential for serious adverse effects.
* Consider gastroprotective agents (e.g., PPIs) in patients with increased risk of GI complications.
* Mefenamic acid is less effective than other NSAIDs for chronic inflammatory conditions like rheumatoid arthritis.
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*Disclaimer: This information is intended for healthcare professionals and should not substitute for a thorough review of the complete prescribing information or consultation with a qualified healthcare provider. Always verify current prescribing information with official sources before making clinical decisions.*
