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# Mefanamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It possesses analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Mild to moderate pain, including menstrual pain (dysmenorrhea).
* Inflammation associated with conditions like rheumatoid arthritis and osteoarthritis.
## Adult Dosing
* **Pain:** 500 mg every 6 to 8 hours as needed.
* **Dysmenorrhea:** 500 mg every 6 to 8 hours as needed, typically starting at the onset of bleeding or pain.
* **Rheumatoid Arthritis/Osteoarthritis:** 500 mg every 6 to 8 hours.
* **Maximum Daily Dose:** 1500 mg. Duration of use for self-medication should not exceed 7 days for pain or 3 days for fever.
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age due to limited safety and efficacy data.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Data is limited, but dose reduction may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. Data is limited.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, 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 history of recurrent gastrointestinal bleeding.
* Severe renal or hepatic impairment.
* Severe heart failure.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, headache, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal failure; hepatic failure; anaphylaxis; Stevens-Johnson syndrome; exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal adverse effects.
* **SSRIs/SNRIs:** Increased risk of gastrointestinal bleeding.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
* **Other NSAIDs/Aspirin:** Increased risk of adverse effects, particularly gastrointestinal.
* **ACE inhibitors/ARBs/Diuretics:** May decrease antihypertensive effect and increase risk of renal impairment.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Renal function (serum creatinine, BUN) especially in patients with pre-existing renal disease or those on concomitant nephrotoxic agents.
* Liver function (ALT, AST) particularly with prolonged use or in patients with hepatic impairment.
* Blood pressure.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Should be used at the lowest effective dose for the shortest duration necessary.
* Consider the risk of serious cardiovascular and gastrointestinal events, especially with prolonged use or in patients with risk factors.
* May mask signs of infection.
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**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for comprehensive prescribing information. Always consult the official prescribing information and current guidelines before making clinical decisions.
