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## Mefenamic Acid
### Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) of the fenamate class. It exhibits analgesic, anti-inflammatory, and antipyretic properties through inhibition of cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
### Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
### Adult Dosing
* **Pain/Dysmenorrhea:** 500 mg orally every 6 hours as needed. Do not exceed 1500 mg in a 24-hour period or 7 days of continuous use.
### Pediatric Dosing
* **Pain/Dysmenorrhea:** Generally not recommended for children under 14 years of age unless under specific medical supervision. Limited data available for pediatric use.
### Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment, though specific guidelines are not well-established.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe impairment, though specific guidelines are not well-established.
### 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.
* Inflammatory bowel disease (active or history of).
* Severe renal or hepatic impairment.
* Third trimester of pregnancy.
### Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, headache, dizziness, rash.
* **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 ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of gastrointestinal bleeding.
* **ACE inhibitors, ARBs, Beta-blockers:** May diminish antihypertensive effect and increase risk of renal impairment.
* **Diuretics:** May diminish diuretic effect and increase risk of renal impairment.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
### Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (melena, hematemesis).
* Monitor for signs of renal toxicity (changes in urine output, BUN, creatinine).
* Monitor for signs of hepatic toxicity (jaundice, elevated liver enzymes).
* Monitor blood pressure.
* Monitor for hypersensitivity reactions.
### Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Shorten duration of therapy to the lowest effective dose.
* Avoid concurrent use with other NSAIDs.
* Consider the increased risk of cardiovascular events and gastrointestinal bleeding with NSAID use, especially in elderly patients or those with a history of these conditions.
**Disclaimer:** This information is intended for clinical professionals. Always consult the most current prescribing information and relevant guidelines before making clinical decisions.
