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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It has analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Do not exceed 4000 mg daily.
* **Dysmenorrhea:** 500 mg every 4-6 hours as needed, starting with the onset of pain or bleeding, whichever comes first. Do not exceed 4000 mg daily.
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age due to limited data on efficacy and safety.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment. Specific guidelines are not established, and close monitoring is recommended.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe impairment. Specific guidelines are not established, and close monitoring is recommended.
* **Elderly:** Increased risk of adverse events. Consider lower doses and closer monitoring.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* History of bronchospasm, 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 (GI) bleeding or history of recurrent GI ulceration/bleeding.
* Severe renal impairment.
* Severe hepatic impairment.
* Severe heart failure.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Abdominal pain, nausea, vomiting, diarrhea, dyspepsia, constipation, headache, dizziness.
* **Serious:** GI bleeding, ulceration, perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal failure; hepatic failure; hypersensitivity reactions (including Stevens-Johnson syndrome and toxic epidermal necrolysis); 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.
* **Aspirin:** May decrease the cardioprotective effect of low-dose aspirin.
* **ACE inhibitors and ARBs:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Diuretics:** May reduce diuretic effect and increase risk of renal impairment.
* **Lithium:** Increased serum lithium levels and risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
* **Other NSAIDs:** Increased risk of adverse effects.
## Monitoring
* Signs and symptoms of GI bleeding or ulceration.
* Renal function (BUN, creatinine).
* Liver function tests (LFTs).
* Blood pressure.
* Signs of fluid retention (edema, weight gain).
* Signs of cardiovascular events.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only.
* Administer with food or milk to minimize GI upset.
* Lowest effective dose should be used for the shortest duration necessary to minimize risks.
* Avoid concurrent use with other NSAIDs.
* Patients with a history of GI disease should be monitored closely.
Please consult the most current prescribing information and relevant clinical guidelines for complete details.
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*This information is intended for healthcare professionals. It is essential to consult the official drug labeling and individual patient factors before making any clinical decisions.*
