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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It exhibits analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Pain, including menstrual pain (dysmenorrhea)
* Mild to moderate pain associated with various conditions
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed.
* **Dysmenorrhea:** 500 mg orally every 6 hours as needed, typically starting with the onset of pain and continuing for the duration of symptoms.
* **Maximum:** 1500 mg orally per day. Use should generally not exceed 7 days.
## Pediatric Dosing
Mefenamic acid is **not recommended** for use in children under 14 years of age for over-the-counter use. Limited data exists for prescription use in specific pediatric populations, and dosing should be determined by a pediatrician based on clinical assessment.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustment recommendations are widely established, but reduced doses may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. No specific dose adjustment recommendations are widely established, but reduced doses may be considered in severe impairment.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* 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.
## Adverse Effects
Common: Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, rash.
Serious: Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal failure; hepatic failure; hypersensitivity reactions; exacerbation of asthma; hypertension.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Lithium:** Increased serum lithium levels and risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
* **Diuretics, ACE inhibitors, Angiotensin II Receptor Blockers (ARBs):** Risk of impaired renal function and potential loss of antihypertensive effect.
## Monitoring
* **Renal function:** Particularly in patients with pre-existing renal disease, dehydration, or those taking concomitant nephrotoxic agents.
* **Hepatic function:** Especially in patients with liver disease.
* **Signs and symptoms of GI bleeding:** Including melena, hematemesis, and abdominal pain.
* **Blood pressure:** NSAIDs can cause new-onset hypertension or worsen existing hypertension.
## Clinical Pearls
* Mefenamic acid is generally intended for short-term use due to the risk of serious adverse effects, particularly GI toxicity.
* It is most effective when taken with food or milk to reduce gastrointestinal upset.
* Consider the risk of cardiovascular thrombotic events, myocardial infarction, and stroke associated with NSAID use.
* The risk of GI toxicity increases with dose and duration of use.
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*This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and your healthcare provider before making any treatment decisions.*
