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# Mefenamic acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) from the fenamate class. It is a weak acid with analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Short-term management of mild to moderate pain, including menstrual pain (dysmenorrhea).
* Relief of inflammatory symptoms associated with conditions like rheumatoid arthritis or osteoarthritis (though typically not a first-line agent for chronic conditions).
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, starting at the onset of pain or bleeding.
* Maximum daily dose: 1500 mg.
* Duration: Not recommended for use longer than 7 days.
## Pediatric Dosing
* Dosing for children under 14 years of age is not well-established. Use with caution and under strict medical supervision. Some sources suggest 6.5 mg/kg every 6 hours, but this is not widely standardized.
## Dose Adjustments
* No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised due to potential for NSAID-related toxicity. Mefenamic acid is generally not recommended in severe renal or hepatic disease.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* 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.
* Inflammatory bowel disease.
* Third trimester of pregnancy.
## Adverse Effects
Common adverse effects include gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), dizziness, drowsiness, and headache. Serious adverse effects can include gastrointestinal bleeding, perforation, renal toxicity, cardiovascular thrombotic events, and hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs):** Increased risk of gastrointestinal bleeding.
* **Other NSAIDs and Aspirin:** Increased risk of gastrointestinal toxicity and other adverse effects.
* **Diuretics, ACE inhibitors, ARBs:** May reduce antihypertensive effect and increase risk of renal toxicity.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding.
* Assess renal function, especially in patients with pre-existing renal disease or those at risk.
* Monitor for signs of cardiovascular events.
* Assess for effectiveness and adverse effects.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* It is generally not recommended for chronic use due to the risk of serious adverse effects and potential for reduced efficacy compared to other NSAIDs for inflammatory conditions.
* Due to the risk of aplastic anemia and agranulocytosis (though rare), prolonged use should be avoided.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant literature for complete details, including dosages, contraindications, warnings, and precautions, before prescribing or administering any medication. Local protocols and guidelines may also apply.
