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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) of the fenamate class. It is used for the short-term symptomatic treatment of mild to moderate pain.
## Primary Indications
* Pain associated with gynecological conditions, such as dysmenorrhea.
* Mild to moderate pain from other causes (e.g., dental pain, headaches).
## Adult Dosing
* **Initial Dose:** 500 mg orally.
* **Subsequent Doses:** 250 mg orally every 6 hours as needed.
* **Maximum Daily Dose:** 1500 mg orally.
* **Duration:** Should not be used for more than 7 consecutive days.
## Pediatric Dosing
Mefenamic acid is **not generally recommended** for use in children under 14 years of age due to limited data and potential safety concerns. When used, dosing should be carefully considered and monitored by a healthcare professional. Specific pediatric dosing is not well-established and may vary based on age and weight; however, some sources suggest a dose of 6.5 mg/kg orally every 6 hours for children over 14 years.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dosage adjustments may be necessary, but specific guidelines are not well-defined. Avoid in severe renal impairment.
* **Hepatic Impairment:** Use with caution. Dosage adjustments may be necessary, but specific guidelines are not well-defined. Avoid in severe hepatic impairment.
* **Elderly:** Consider reduced doses due to increased risk of adverse effects.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of gastrointestinal bleeding or perforation related to prior NSAID use.
* Active or history of recurrent peptic ulceration or hemorrhage.
* Severe heart failure.
* Severe renal or hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, dyspepsia, headache, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal toxicity; hepatic toxicity; cardiovascular thrombotic events; hypersensitivity reactions; Stevens-Johnson syndrome; toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of gastrointestinal bleeding.
* **Diuretics and Antihypertensives:** May decrease their efficacy and increase risk of renal toxicity.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* **Signs and symptoms of GI bleeding:** Black tarry stools, hematemesis, abdominal pain.
* **Renal function:** Especially in patients with pre-existing renal disease or those at risk.
* **Liver function:** Especially with prolonged use or in patients with liver disease.
* **Blood pressure:** NSAIDs can cause fluid retention and hypertension.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only.
* Administer with food or milk to minimize gastrointestinal upset.
* Patients should be advised to report any signs of gastrointestinal bleeding or other serious adverse effects immediately.
* Due to potential for drowsiness and dizziness, caution patients when driving or operating machinery.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and clinical guidelines before making any treatment decisions.*
