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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It exerts its effects by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Pain, including menstrual pain (dysmenorrhea)
* Mild to moderate pain
## Adult Dosing
* **Initial dose:** 500 mg
* **Subsequent doses:** 250 mg every 6 hours as needed.
* **Maximum daily dose:** 1500 mg
## Pediatric Dosing
* Generally not recommended for children under 14 years of age.
* When used, dosage is typically weight-based. **Specific pediatric dosing must be confirmed with current prescribing information or local protocol.** A common regimen is 6.5 mg/kg every 6 hours for children 6 months and older, not to exceed 500 mg per dose or 1500 mg per day.
## Dose Adjustments
* No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised. Monitor closely for adverse effects.
## 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.
* Severe heart failure.
* Severe renal or hepatic impairment.
## Adverse Effects
Common adverse effects include gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), headache, dizziness, and rash. Serious adverse effects include GI bleeding, ulceration, perforation, renal toxicity, cardiovascular events, and hypersensitivity reactions.
## 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.
* **ACE inhibitors and Angiotensin II Receptor Blockers (ARBs):** Reduced antihypertensive effect, increased risk of renal impairment.
* **Diuretics:** Reduced diuretic effect, increased risk of renal impairment.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* **Gastrointestinal:** Monitor for signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* **Renal:** Monitor renal function, especially in patients with pre-existing renal disease or those taking nephrotoxic agents.
* **Cardiovascular:** Assess for signs of fluid retention or edema.
## Clinical Pearls
* Administer with food or milk to minimize GI upset.
* Short-term use only.
* Avoid concurrent use with other NSAIDs.
* Due to potential for renal toxicity and GI bleeding, use the lowest effective dose for the shortest duration necessary.
***
**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant guidelines before making clinical decisions. Drug information can change, and the latest product monographs or official drug compendia should be referenced for complete and up-to-date details.
