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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) with analgesic and anti-inflammatory properties. It is a weak acid and a fenamate derivative.
## Primary Indications
* Relief of mild to moderate pain, including menstrual pain (dysmenorrhea).
* Symptomatic relief of rheumatoid arthritis and osteoarthritis.
## Adult Dosing
* **Pain:** 500 mg every 4 to 6 hours as needed. Not to exceed 1000 mg for any single dose or 4000 mg per day.
* **Dysmenorrhea:** 500 mg every 4 to 6 hours as needed, starting at the onset of menstrual pain.
* **Rheumatoid Arthritis/Osteoarthritis:** 500 mg three times daily, with meals.
## Pediatric Dosing
* Generally not recommended for children under 14 years of age due to potential for serious adverse effects. For specific indications and age groups, consult pediatric guidelines. Some sources suggest 6.5 mg/kg every 6 hours, not to exceed adult maximums.
## Dose Adjustments
* No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised due to potential for NSAID-induced toxicity. Mefenamic acid is generally not recommended in patients with severe renal or hepatic disease.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of bronchospasm, asthma, rhinitis, or urticarial reactions after taking aspirin or other NSAIDs.
* Peri-operative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain, constipation), dizziness, drowsiness.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal impairment; hepatic dysfunction; cardiovascular thrombotic events; hypersensitivity reactions; Stevens-Johnson syndrome/toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of gastrointestinal adverse effects and potentially additive pharmacologic effects.
* **ACE inhibitors, ARBs, diuretics:** Reduced antihypertensive effect; increased risk of renal impairment.
* **Lithium, Methotrexate:** Increased serum concentrations and potential for toxicity.
## Monitoring
* **Renal function:** Particularly in elderly patients or those with pre-existing renal disease.
* **Hepatic function:** Monitor for signs of liver injury.
* **Gastrointestinal symptoms:** Assess for signs of bleeding or ulceration.
* **Blood pressure:** Monitor for potential hypertensive effects.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Limit use to the shortest duration necessary due to potential for serious adverse effects.
* Not typically a first-line agent for chronic inflammatory conditions compared to other NSAIDs.
* Use with caution in patients with cardiovascular disease or risk factors.
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**Disclaimer:** This information is intended for healthcare professionals. It is essential to consult the most current prescribing information and relevant clinical guidelines for complete details and to ensure patient-specific appropriateness before making any treatment decisions.
