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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term treatment of mild to moderate pain.
## Primary Indications
* Pain associated with osteoarthritis and rheumatoid arthritis (less common due to risk profile).
* Primary dysmenorrhea.
* Mild to moderate pain, including dental pain and post-operative pain.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Primary Dysmenorrhea:** 500 mg every 6 hours as needed, starting at the onset of pain and bleeding.
* **Maximum Daily Dose:** 1500 mg (This is for short-term use; longer-term use may have different recommendations, but generally NSAIDs are not first-line for chronic pain).
## Pediatric Dosing
* **Pain and Dysmenorrhea:** Mefenamic acid is generally not recommended for children under 14 years of age due to limited data and potential for adverse effects. For those 14 years and older, adult dosing can be considered.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary 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.
* Peri-operative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal bleeding or ulcer disease.
* Severe renal or hepatic impairment.
* Pregnancy (especially third trimester).
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal failure; hepatic failure; hypersensitivity reactions; exacerbation of asthma; fluid retention and edema.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Other NSAIDs/Aspirin:** Increased risk of GI toxicity and other adverse effects.
* **ACE Inhibitors, ARBs, Beta-blockers:** May reduce antihypertensive efficacy; increased risk of renal impairment.
* **Diuretics:** May reduce diuretic efficacy; increased risk of renal impairment.
* **Lithium, Methotrexate:** Increased serum levels and toxicity.
## Monitoring
* **GI Bleeding:** Monitor for signs and symptoms (e.g., melena, hematemesis, abdominal pain).
* **Renal Function:** Monitor BUN and creatinine, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic Function:** Monitor LFTs, especially in patients with pre-existing liver disease or those at risk.
* **Blood Pressure:** Monitor for potential increases, especially in patients with hypertension.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize GI upset.
* It is intended for short-term use only.
* Due to its adverse effect profile, it is often a less preferred NSAID for chronic conditions.
* Ensure adequate hydration, particularly in elderly patients or those with renal compromise.
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*Disclaimer: This information is intended for clinical decision-making and should not replace a thorough review of the current prescribing information and institutional protocols.*
