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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 and for managing primary dysmenorrhea.
## Primary Indications
* Mild to moderate pain (e.g., dental pain, musculoskeletal pain).
* Primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 4 to 6 hours as needed. Do not exceed 4000 mg/day.
* **Primary Dysmenorrhea:** 500 mg every 4 to 6 hours as needed, starting with the onset of pain or bleeding. Do not exceed 4000 mg/day.
* Treatment should generally not exceed 7 days.
## Pediatric Dosing
Mefenamic acid is not typically recommended for children under 14 years of age due to lack of established safety and efficacy data.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustments are established, but dose reduction may be considered in severe impairment. Monitor renal function closely.
* **Hepatic Impairment:** Use with caution. No specific dose adjustments are established. Monitor liver function.
* **Elderly:** Elderly patients may be at increased risk for adverse effects. Use the lowest effective dose.
## Contraindications
* Known 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.
* Active gastrointestinal bleeding or a history of recurrent gastrointestinal ulceration or bleeding.
* Severe renal or hepatic impairment.
* Severe heart failure.
## Adverse Effects
* **Common:** Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), dizziness, headache, rash.
* **Serious:** Gastrointestinal bleeding/perforation, renal failure, hepatic failure, cardiovascular thrombotic events (MI, stroke), hypersensitivity reactions, Stevens-Johnson syndrome, toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal bleeding.
* **Other NSAIDs/Aspirin:** Increased risk of gastrointestinal adverse effects and may reduce cardioprotective effects of low-dose aspirin.
* **ACE inhibitors, ARBs, Beta-blockers:** May reduce antihypertensive effect; increased risk of renal impairment.
* **Diuretics:** May reduce diuretic efficacy and increase risk of renal impairment.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* **GI Symptoms:** Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* **Renal Function:** Monitor serum creatinine and BUN, especially in patients with pre-existing renal disease or those on concomitant nephrotoxic agents.
* **Hepatic Function:** Monitor liver enzymes (ALT, AST), especially in patients with pre-existing liver disease.
* **Blood Pressure:** Monitor blood pressure, especially in patients receiving antihypertensive therapy.
* **Signs of Cardiovascular Events:** Advise patients to seek immediate medical attention for chest pain, shortness of breath, weakness, or slurring of speech.
## Clinical Pearls
* Administer with food or milk to reduce gastrointestinal upset.
* Use for the shortest duration necessary to control symptoms.
* Consider the risks of NSAID use (GI, renal, cardiovascular) when initiating therapy.
* Avoid concomitant use with other NSAIDs.
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**Disclaimer:** This information is intended for clinical use and does not replace professional medical advice. Always consult the most current prescribing information and relevant guidelines for definitive drug management decisions.
