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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, including menstrual pain. It works by inhibiting prostaglandin synthesis.
## Primary Indications
* Mild to moderate pain
* Primary dysmenorrhea
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Treatment should not exceed 7 days.
* **Primary Dysmenorrhea:** 500 mg every 6 hours, starting at the onset of pain and bleeding, and continuing for the duration of dysmenorrhea.
## Pediatric Dosing
Mefenamic acid is **not recommended** for use in children under 14 years of age for pain relief. Limited data exists for other indications.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised due to potential for exacerbation of underlying conditions. Mefenamic acid is generally not recommended in patients with severe renal or hepatic impairment.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* History of bronchospasm, asthma, allergic rhinitis, or urticaria triggered by 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 bleeding.
* Inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis).
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include nausea, vomiting, diarrhea, abdominal pain, constipation, and dyspepsia. More serious adverse effects include:
* **Gastrointestinal:** GI bleeding, ulceration, perforation.
* **Cardiovascular:** Increased risk of myocardial infarction, stroke, and new-onset or worsening hypertension.
* **Renal:** Renal impairment, interstitial nephritis, papillary necrosis.
* **Hepatic:** Hepatic impairment.
* **Hypersensitivity:** Rash, pruritus, urticaria, angioedema, Stevens-Johnson syndrome, toxic epidermal necrolysis.
* **Hematologic:** Anemia, leukopenia.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Diuretics and Antihypertensives:** NSAIDs may decrease their efficacy and increase the risk of renal impairment.
* **Lithium:** NSAIDs can increase lithium levels. Monitor lithium levels.
* **Methotrexate:** NSAIDs can increase methotrexate toxicity.
## Monitoring
* **GI Symptoms:** Monitor for signs and symptoms of GI bleeding.
* **Renal Function:** Monitor renal function, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic Function:** Monitor liver function tests, especially with prolonged use.
* **Blood Pressure:** Monitor blood pressure.
## Clinical Pearls
* Administer with food or milk to minimize GI upset.
* Use the lowest effective dose for the shortest duration necessary.
* Avoid concomitant use with other NSAIDs.
* Due to potential for serious GI adverse events, mefenamic acid is generally reserved for short-term use.
* Consider alternative analgesics for patients with a history of peptic ulcer disease or GI bleeding.
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*Please verify current prescribing information and consult with a healthcare professional for any medical advice or before making any treatment decisions.*
