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# Amoxicillin-Clavulanate (Amox-Clav) ## Overview Amoxicillin-Clavulanate is a combination penicillin-class antibiotic consisting of a broad-spectrum penicillin (amoxicillin) and a beta-lactamase inhibitor (clavulanate). This combination expands the spectrum of activity to include beta-lactamase-producing organisms (e.g., *H. influenzae, M. catarrhalis, S. aureus*). ## Primary Indications Commonly used for acute bacterial rhinosinusitis, community-acquired pneumonia, otitis media, animal/human bites, and skin/soft tissue infections. ## Adult Dosing Standard dosing is based on the amoxicillin component. Common regimens include: * **Mild to Moderate Infections:** 500 mg amoxicillin/125 mg clavulanate PO every 8 hours OR 875 mg/125 mg PO every 12 hours. * **Severe Infections/Respiratory Infection:** 2000 mg/125 mg (extended-release tablet) PO every 12 hours. * *Note:* The 875 mg/125 mg strength is preferred to minimize clavulanate-associated diarrhea while maintaining high trough levels. ## Pediatric Dosing **Dosing is weight-based (based on the amoxicillin component):** * **General Dosage:** 25 mg/kg/day to 45 mg/kg/day divided every 12 hours (using the 4:1 or 7:1 ratio formulations). * **Otitis Media/Severe Infections:** 80 mg/kg/day to 90 mg/kg/day divided every 12 hours. * **Max Pediatric Dose:** Refer to adult dosing limits for older children; do not exceed 875 mg amoxicillin per dose using the 125 mg clavulanate formulations. ## Dose Adjustments * **Renal Impairment (CrCl <30 mL/min):** Dosage reductions are required. Do not use the 875 mg formulation. Consult local renal dosing guidelines (e.g., Lexicomp/UpToDate) as adjustments are specific to the ratio of amoxicillin to clavulanate. * **Hepatic Impairment:** Use with caution; monitor liver function tests. ## Contraindications * History of serious hypersensitivity reactions (e.g., anaphylaxis, Stevens-Johnson syndrome) to any penicillin. * History of cholestatic jaundice or hepatic dysfunction associated with previous amoxicillin-clavulanate use. ## Adverse Effects * **Gastrointestinal:** Diarrhea (very common due to clavulanate), nausea, vomiting. * **Dermatologic:** Rash (typically non-allergic maculopapular rash, often seen in EBV patients). * **Hepatic:** Elevated LFTs, rare cases of cholestatic jaundice. * **Hypersensitivity:** Anaphylaxis, urticaria. ## Key Drug Interactions * **Methotrexate:** May decrease clearance of methotrexate, increasing toxicity risk. * **Warfarin:** May enhance anticoagulant effect; monitor INR. * **Oral Contraceptives:** Potential for decreased efficacy (highly controversial, but use backup barrier method during treatment). * **Probenecid:** Decreases renal tubular secretion of amoxicillin, increasing blood levels. ## Monitoring * Monitor for signs of hypersensitivity (rash, wheezing). * Monitor bowel habits for *C. difficile*-associated diarrhea. * For prolonged therapy (>14 days), monitor LFTs and CBC (potential for leukopenia/thrombocytopenia). ## Clinical Pearls * **Formulation Warning:** 250 mg tablets and 500 mg tablets contain different amounts of clavulanate; these are **not** interchangeable. * **Adherence:** Take with food to minimize GI upset and improve absorption of clavulanate. * **Antibiotic Stewardship:** Avoid using for viral URIs (colds/flu). * **Dosing Ratio:** Always specify the ratio or the exact milligram strength when prescribing to avoid underdosing or overdosing of the clavulanate component. *** *Disclaimer: This information is for educational purposes only. Always verify current prescribing information, institutional protocols, and patient-specific factors (e.g., allergies, renal function) with a clinical pharmacist or current drug resource before prescribing or administering medication.*