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# Mefenamic 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, particularly associated with menstrual cramps (primary dysmenorrhea).
* Pain associated with dental procedures.
* Rheumatoid arthritis and osteoarthritis (though less commonly used than other NSAIDs for chronic inflammatory conditions).
## Adult Dosing
* **Pain (including dysmenorrhea):** 500 mg every 6 hours as needed. Therapy should not exceed 7 days.
* **Rheumatoid arthritis/Osteoarthritis:** Doses up to 1500 mg daily in divided doses.
## Pediatric Dosing
* **Pain and fever:** Generally not recommended for children under 14 years of age. Safety and efficacy have not been established.
## 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.
* **Elderly:** Increased risk of adverse effects; consider lower doses and monitor closely.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of bronchospasm, asthma, rhinitis, or urticaria following aspirin or NSAID administration.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active peptic ulceration or GI bleeding.
* Severe renal or hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, headache, dizziness, rash, pruritus.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal toxicity (including interstitial nephritis, papillary necrosis, renal failure); hepatic toxicity; cardiovascular thrombotic events (MI, 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 ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
* **ACE inhibitors, ARBs, diuretics:** Reduced antihypertensive effect, increased risk of renal impairment.
* **Other NSAIDs (including aspirin):** Increased risk of GI toxicity and other adverse effects.
## Monitoring
* Signs and symptoms of GI bleeding or ulceration.
* Renal function (BUN, creatinine).
* Liver function tests (ALT, AST).
* Blood pressure.
* Signs of fluid retention or edema.
## Clinical Pearls
* Mefenamic acid is generally intended for short-term use due to the risk of GI and renal adverse effects.
* The maximum recommended duration of therapy for pain is 7 days in adults.
* Always advise patients to take with food or milk to minimize GI upset.
* Discontinue immediately if signs of GI bleeding or hepatic/renal dysfunction occur.
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**Disclaimer:** This information is intended for educational purposes and does not substitute for professional medical advice. Always consult with a qualified healthcare provider to determine the appropriateness of any medication for a specific patient and to verify current prescribing information.
