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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, starting with the onset of pain or bleeding, whichever occurs first.
* **Maximum:** 1500 mg per day for more than 7 days of treatment. For short-term use (up to 7 days), the maximum dose is 3000 mg per day.
## Pediatric Dosing
Mefenamic acid is not generally recommended for children under 14 years of age due to limited data. Consult pediatric-specific guidelines or specialist recommendations for use in younger patients.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised. Mefenamic acid is contraindicated in patients with severe renal or hepatic disease.
## 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.
* Severe renal impairment.
* Severe hepatic impairment.
* Severe heart failure.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, headache, dizziness.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal failure; hepatic failure; hypersensitivity reactions (including Stevens-Johnson syndrome, toxic epidermal necrolysis); bronchospasm.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI adverse effects.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Other NSAIDs:** Increased risk of adverse effects.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
* **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect and increased risk of renal impairment.
## Monitoring
* **GI symptoms:** Monitor for signs and symptoms of GI bleeding and ulceration.
* **Renal function:** Assess baseline and periodic renal function, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic function:** Assess baseline and periodic hepatic function.
* **Blood pressure:** Monitor blood pressure, especially with long-term use.
* **Signs of cardiovascular events:** Advise patients to seek medical attention for chest pain, shortness of breath, weakness, or slurring of speech.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only.
* Administer with food or milk to minimize GI upset.
* Consider the lowest effective dose for the shortest duration necessary to reduce the risk of adverse events.
* Be aware of the increased risk of cardiovascular and gastrointestinal events associated with NSAIDs.
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***Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making treatment decisions.*
