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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) of the fenamate class. It acts by inhibiting cyclooxygenase (COX-1 and COX-2) enzymes, reducing prostaglandin synthesis. Its primary use is in the treatment of mild to moderate pain and dysmenorrhea.
## Primary Indications
* Primary dysmenorrhea.
* Mild to moderate pain (short-term management, usually ≤ 7 days).
* *Note: "Meftal-P" specifically is often marketed as a pediatric suspension for pain and fever, though guidelines vary by region.*
## Adult Dosing
* **Acute Pain/Dysmenorrhea:** 500 mg orally as an initial dose, followed by 250 mg every 6 hours as needed.
* **Maximum Dose:** Do not exceed 1.5 g (1500 mg) per day. Treatment duration should not exceed 7 days.
## Pediatric Dosing
* Pediatric dosing is highly dependent on local protocol and specific formulation (concentration of suspension).
* **General Guidance:** Typically 6.5 mg/kg administered every 8 hours.
* **Safety Warning:** Mefenamic acid is generally not recommended for children under 14 years of age unless specifically authorized by local clinical guidelines or pediatric product labeling. Always confirm the concentration of the suspension before calculating dose.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Avoid in severe renal impairment (CrCl < 30 mL/min).
* **Hepatic Impairment:** Use with caution. Consider lower doses as the drug is extensively metabolized by the liver.
## Contraindications
* Known hypersensitivity to mefenamic acid or other NSAIDs (including aspirin-induced asthma/urticaria).
* Active peptic ulceration or inflammatory bowel disease.
* History of GI bleeding or perforation related to previous NSAID therapy.
* Severe heart failure, severe hepatic failure, or severe renal impairment.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Abdominal pain, nausea, diarrhea (often dose-dependent), and dyspepsia.
* **Serious:** GI ulceration/bleeding, cardiovascular events (MI, stroke), hypertension, fluid retention/edema, renal impairment, and severe skin reactions (e.g., Stevens-Johnson syndrome).
## Key Drug Interactions
* **Anticoagulants (Warfarin):** Increased risk of bleeding due to antiplatelet effects and gastric mucosal damage.
* **Other NSAIDs/Aspirin:** Increased risk of GI toxicity and bleeding.
* **Antihypertensives (ACE inhibitors/Diuretics):** NSAIDs may reduce the antihypertensive effect and increase the risk of acute renal failure.
* **Lithium/Methotrexate:** NSAIDs may decrease the renal clearance of these drugs, increasing risk of toxicity.
## Monitoring
* Monitor for signs of GI bleeding (occult blood, anemia).
* Assess blood pressure periodically during chronic or prolonged use.
* Monitor renal function (serum creatinine) in elderly patients or those with existing cardiovascular disease.
* Evaluate liver function if clinical signs of hepatotoxicity appear.
## Clinical Pearls
* **Take with food/milk:** Administering with food may help reduce gastrointestinal irritation.
* **Short-term use:** It is intended for short-term use only; chronic use increases the risk of serious adverse cardiovascular and gastrointestinal events.
* **Hydration:** Ensure the patient remains adequately hydrated to minimize renal risk.
* **Discontinuation:** Advise patients to stop taking the drug and seek medical attention if they experience black/tarry stools, severe stomach pain, or signs of an allergic reaction (rash, wheezing).
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**Educational Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Dosing, indications, and safety information can vary by country and specific manufacturer labeling. Always verify current prescribing information, local clinical protocols, and pharmacy guidelines before prescribing or dispensing any medication.
