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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 reversible inhibitor of cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain, including menstrual pain (dysmenorrhea).
* Relief of pain associated with musculoskeletal disorders.
## Adult Dosing
* **Pain/Dysmenorrhea:** 500 mg every 4 to 6 hours as needed. Do not exceed 1500 mg in a 24-hour period. Treatment should not exceed 7 days.
## Pediatric Dosing
* **Pain/Dysmenorrhea:** Dosing is not well-established in pediatric patients. Consult specific pediatric guidelines or a pediatric specialist.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No specific dose adjustment is recommended, but monitoring of renal function is advised. Discontinue if signs of renal toxicity occur.
* **Hepatic Impairment:** Use with caution. No specific dose adjustment is recommended, but monitoring of liver function is advised. Discontinue if signs of hepatic toxicity occur.
## 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.
* Active gastrointestinal bleeding or history of recurrent gastrointestinal ulceration/bleeding.
* Severe renal or hepatic impairment.
* Severe heart failure.
## Adverse Effects
* **Gastrointestinal:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, heartburn, ulceration, bleeding, perforation.
* **Central Nervous System:** Dizziness, drowsiness, headache.
* **Renal:** Renal insufficiency, acute kidney injury, interstitial nephritis.
* **Hepatic:** Elevated liver enzymes, hepatitis.
* **Hematologic:** Anemia, leukopenia, thrombocytopenia.
* **Dermatologic:** Rash, pruritus, Stevens-Johnson syndrome, toxic epidermal necrolysis.
* **Cardiovascular:** Edema, hypertension, increased risk of myocardial infarction and stroke.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs):** Increased risk of gastrointestinal bleeding.
* **Diuretics, ACE Inhibitors, Angiotensin II Receptor Blockers (ARBs):** NSAIDs can reduce the antihypertensive effect and increase the risk of renal toxicity.
* **Lithium, Methotrexate:** NSAIDs can increase serum levels and toxicity of these drugs.
* **Other NSAIDs or Salicylates:** Increased risk of adverse effects, particularly gastrointestinal.
## Monitoring
* **Gastrointestinal:** Assess for signs and symptoms of bleeding or ulceration.
* **Renal Function:** Monitor BUN, creatinine, and urine output, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic Function:** Monitor liver enzymes (ALT, AST), especially in patients with liver disease or those on long-term therapy.
* **Blood Pressure:** Monitor for hypertension.
* **Electrolytes:** Monitor as clinically indicated.
## Clinical Pearls
* Mefenamic acid is generally recommended for short-term use only.
* Administer with food or milk to minimize gastrointestinal upset.
* Due to potential for renal and hepatic toxicity, use with caution in elderly patients or those with compromised organ function.
* Discontinue if significant adverse effects occur or if symptoms do not improve within 7 days.
* The risk of cardiovascular thrombotic events, myocardial infarction, and stroke is associated with NSAID use.
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**Disclaimer:** This information is intended for clinical pharmacists and healthcare professionals. It is essential to consult the most current prescribing information and relevant clinical guidelines for definitive patient management decisions. Dosing and indications may vary based on local protocols and individual patient factors.
