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# Mefenamic Acid
## Overview
Mefenamic acid is a non-steroidal anti-inflammatory drug (NSAID) of the fenamate class.
## Primary Indications
* Mild to moderate pain, including menstrual pain (dysmenorrhea).
* Inflammation associated with conditions like rheumatoid arthritis and osteoarthritis.
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed. Maximum daily dose: 1500 mg.
* **Dysmenorrhea:** 500 mg orally every 6 hours as needed, starting with the onset of pain or bleeding.
* **Rheumatoid Arthritis/Osteoarthritis:** 500 mg orally three times daily. (Less common indication due to availability of other NSAIDs).
## Pediatric Dosing
* **Pain/Dysmenorrhea:** Generally not recommended for children under 14 years of age.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Data is limited; consider dose reduction if significant impairment.
* **Hepatic Impairment:** Use with caution. Data is limited; consider dose reduction.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of gastrointestinal (GI) bleeding or perforation related to prior NSAID use.
* Active peptic ulceration or recurrent GI bleeding.
* Severe heart failure, renal failure, or hepatic failure.
* Late pregnancy (third trimester).
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, dyspepsia, constipation, headache, dizziness.
* **Serious:** GI bleeding, ulceration, perforation; renal toxicity (including interstitial nephritis, papillary necrosis); hepatic toxicity; cardiovascular thrombotic events (myocardial infarction, stroke); hypersensitivity reactions; exacerbation of asthma; Stevens-Johnson syndrome/toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of GI toxicity and other adverse effects.
* **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect; increased risk of renal toxicity.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* Signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* Renal function (BUN, creatinine) especially in patients with pre-existing renal disease or those at risk.
* Liver function tests (AST, ALT) especially with prolonged use or in patients with hepatic impairment.
* Blood pressure.
* Signs of hypersensitivity reactions.
## Clinical Pearls
* Short-term use for pain is preferred.
* Administer with food or milk to minimize GI upset.
* Avoid in patients with a history of peptic ulcer disease if alternative agents are available.
* Diarrhea is a common and dose-limiting side effect.
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This information is intended for healthcare professionals. Always consult the current prescribing information and relevant literature for complete and up-to-date details before initiating or modifying therapy.
