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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the anthranilic acid derivatives class. It is primarily used for the short-term management of mild to moderate pain.
## Primary Indications
* Pain associated with osteoarthritis and rheumatoid arthritis.
* Primary dysmenorrhea.
* Mild to moderate pain, including dental pain, post-operative pain, and musculoskeletal pain.
## Adult Dosing
* **Pain and Dysmenorrhea:** 500 mg every 6 hours as needed. Do not exceed 1500 mg in a 24-hour period for short-term use (up to 7 days).
* **Arthritis:** 500 mg every 6 hours. Maximum daily dose is typically 1000 mg for chronic use, although some sources may suggest up to 1500 mg for short periods. Long-term use should be carefully considered due to potential risks.
## Pediatric Dosing
Mefenamic acid is **not typically recommended for children under 14 years of age** due to lack of established safety and efficacy data.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dosage adjustments are established, but dose reduction may be considered in severe impairment.
* **Hepatic Impairment:** Use with caution. No specific dosage adjustments are established.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of bronchospasm, asthma, rhinitis, or urticaria following aspirin or other NSAID administration.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease (active or history).
* Severe heart failure, renal impairment, or hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Gastrointestinal:** Diarrhea (most common), nausea, vomiting, abdominal pain, constipation, dyspepsia. Serious GI bleeding, ulceration, and perforation can occur.
* **Central Nervous System:** Dizziness, headache, drowsiness.
* **Renal:** Fluid retention, edema, hypertension, renal insufficiency.
* **Hematologic:** Leukopenia, thrombocytopenia, eosinophilia.
* **Dermatologic:** Rash, pruritus.
* **Other:** Bronchospasm (especially in aspirin-sensitive individuals), tinnitus.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **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:** Reduced diuretic effect and increased risk of renal toxicity.
* **Lithium:** Increased lithium levels and risk of toxicity.
* **Methotrexate:** Increased methotrexate levels and risk of toxicity.
* **Other NSAIDs:** Increased risk of adverse effects, particularly GI bleeding.
## Monitoring
* Monitor for signs and symptoms of GI bleeding (melena, hematemesis).
* Monitor renal function (BUN, creatinine) periodically, especially in patients with pre-existing renal disease or those at risk.
* Monitor blood pressure, as NSAIDs can cause fluid retention and hypertension.
* Monitor for signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid is generally intended for **short-term use only**.
* Due to a higher incidence of diarrhea compared to other NSAIDs, it should be used with caution in patients prone to or experiencing diarrhea.
* Administer with food or milk to minimize GI upset.
* Avoid concurrent use with other NSAIDs, including aspirin, unless specifically indicated and closely monitored.
* Ensure patient is not pregnant, especially in the third trimester.
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**Disclaimer:** This information is intended for clinical use and does not replace comprehensive drug information resources. Always consult the most current prescribing information or a reliable drug database before making clinical decisions.
