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# Meftal (Mefenamic Acid)
## Overview
Mefenamic acid is an anthranilic acid derivative nonsteroidal anti-inflammatory drug (NSAID). It exerts analgesic, anti-inflammatory, and antipyretic effects by inhibiting the cyclooxygenase (COX-1 and COX-2) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Primary dysmenorrhea.
* Mild to moderate acute pain (short-term use, typically ≤7 days).
## Adult Dosing
* **Standard dose:** 500 mg initially, followed by 250 mg every 6 hours as needed.
* **Maximum duration:** Do not exceed 7 days of treatment due to increased risk of gastrointestinal and renal toxicity.
## Pediatric Dosing
* **Children ≥14 years:** Use adult dosing guidelines.
* **Children <14 years:** Safety and efficacy are not established; use is generally not recommended unless under specialized pediatric rheumatology guidance.
## Dose Adjustments
* **Renal Impairment:** Avoid in patients with severe renal impairment (CrCl <30 mL/min). Use with caution in mild-to-moderate impairment; monitor renal function closely.
* **Hepatic Impairment:** Reduce dose or avoid in severe hepatic impairment.
* **Geriatric Patients:** Use the lowest effective dose for the shortest duration possible due to increased risk of CV, GI, and renal adverse events.
## Contraindications
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Peri-operative pain management in the setting of coronary artery bypass graft (CABG) surgery.
* Severe renal or hepatic impairment.
* Active peptic ulceration or inflammatory bowel disease.
* History of gastrointestinal bleeding or perforation related to previous NSAID therapy.
## Adverse Effects
* **Common:** Nausea, abdominal pain, diarrhea (may be severe), constipation, dyspepsia.
* **Serious:** GI bleeding/ulceration, fluid retention, hypertension, hepatotoxicity, renal failure, increased risk of cardiovascular thrombotic events (myocardial infarction, stroke).
* **Hematologic:** Hemolytic anemia (rare, with long-term use).
## Key Drug Interactions
* **Anticoagulants (e.g., Warfarin):** Increased risk of bleeding; monitor INR closely.
* **Antiplatelets/SSRIs:** Increased risk of GI bleeding.
* **ACE Inhibitors/ARBs/Diuretics:** Decreased antihypertensive effect; increased risk of acute kidney injury.
* **Lithium/Methotrexate:** Decreased renal clearance, leading to potential toxicity.
## Monitoring
* **Baseline:** Serum creatinine, LFTs, and CBC (if long-term usage).
* **Ongoing:** Blood pressure monitoring, signs of GI bleeding (melena, hematemesis), symptoms of edema, and renal function.
## Clinical Pearls
* **Administration:** Take with food or milk to minimize gastrointestinal irritation.
* **Duration Limit:** Unlike other NSAIDs, mefenamic acid is strictly indicated for short-term use (≤7 days) due to the higher incidence of diarrhea and secondary GI side effects.
* **Cardiovascular Risk:** All NSAIDs carry a warning for increased risk of serious cardiovascular thrombotic events.
* **Patient Education:** Advise patients to avoid concurrent use of other NSAIDs, including over-the-counter ibuprofen or naproxen, to prevent additive toxicity.
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**Disclaimer:** This information is for educational purposes only. Clinical protocols may vary by institution. Always verify specific dosing, safety warnings, and contraindications via official local prescribing information or an authoritative drug database (e.g., Lexicomp, UpToDate) before prescribing or administering medication.
