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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) of the fenamate class. It possesses analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Short-term management of mild to moderate pain.
* Primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, starting at the onset of pain and bleeding.
* **Maximum Daily Dose:** 1500 mg. Treatment should not exceed 7 days.
## Pediatric Dosing
* Mefenamic acid is generally **not recommended** for use in children under 14 years of age due to limited efficacy and safety data.
* For specific situations or very limited indications, pediatric dosing is not well-established and requires careful consideration by a qualified prescriber.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustments are established, but dose reduction may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. No specific dose adjustments are established, but dose reduction may be considered in severe impairment.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* 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 GI bleeding/ulceration.
* Severe heart failure, renal impairment, or hepatic impairment.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, dyspepsia, rash, dizziness.
* **Serious:**
* GI bleeding, ulceration, perforation.
* Cardiovascular thrombotic events (myocardial infarction, stroke).
* Renal and hepatic toxicity.
* Hypersensitivity reactions (including Stevens-Johnson syndrome, toxic epidermal necrolysis).
* Exacerbation of asthma.
* Hematologic effects (anemia, leukopenia).
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of GI adverse effects, potential for additive renal effects.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Diuretics and antihypertensives:** May reduce efficacy and increase risk of renal toxicity.
* **Lithium:** Increased serum lithium levels and toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* Signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* Renal function (BUN, creatinine) and liver function tests (LFTs), especially with prolonged use or in patients with risk factors.
* Blood pressure.
* Signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize GI upset.
* Due to the risk of diarrhea, it is generally recommended for short-term use only (maximum 7 days).
* Its efficacy for pain relief is comparable to other NSAIDs.
* Consider gastroprotective agents (e.g., PPIs) in patients at high risk for GI complications.
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**Disclaimer:** This information is intended for clinical use and does not replace detailed prescribing information or professional judgment. Always consult the most current official prescribing information and relevant guidelines before making any treatment decisions. Dosing and recommendations may vary based on specific patient factors and local protocols.
