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# Amoxicillin-Clavulanate (Augmentin)
## Overview
Amoxicillin-clavulanate is a combination penicillin-class antibiotic consisting of amoxicillin (a beta-lactam) and clavulanic acid (a beta-lactamase inhibitor). The addition of clavulanate expands the spectrum of activity to include beta-lactamase-producing strains.
## Primary Indications
* Acute bacterial rhinosinusitis
* Community-acquired pneumonia
* Skin and skin structure infections
* Animal/human bites
* Acute otitis media
* Urinary tract infections (less common due to resistance)
## Adult Dosing
* **Mild to moderate infections:** 500 mg every 8 hours or 875 mg every 12 hours.
* **Severe infections / Respiratory tract:** 875 mg every 12 hours.
* **Extended-release (XR) formulation:** 2000 mg every 12 hours (indicated for resistant *S. pneumoniae*).
* *Note:* Always utilize the lowest ratio of clavulanate required to minimize gastrointestinal side effects.
## Pediatric Dosing
* **Standard dose:** 25–45 mg/kg/day (based on amoxicillin component) divided every 12 hours.
* **Acute Otitis Media (High-dose):** 90 mg/kg/day divided every 12 hours using 7:1 or 14:1 formulations.
* **Dosing note:** Use specific pediatric concentrations (e.g., 200 mg/5 mL, 400 mg/5 mL) to ensure the correct amoxicillin-to-clavulanate ratio. Do not use 250 mg tablets due to excessive clavulanate content leading to diarrhea.
## Dose Adjustments
* **Renal Impairment:**
* CrCl 10–30 mL/min: Increase interval to every 12 hours.
* CrCl < 10 mL/min: Increase interval to every 24 hours.
* Avoid using the 875 mg or ER tablets in patients with severe renal impairment due to fixed ratios.
* **Hepatic Impairment:** Use with caution; monitor liver function periodically.
## Contraindications
* History of serious hypersensitivity (anaphylaxis) to any penicillin or cephalosporin.
* History of cholestatic jaundice or hepatic dysfunction associated with previous amoxicillin-clavulanate use.
## Adverse Effects
* **Common:** Diarrhea (frequent, dose-related), nausea, vomiting, abdominal pain.
* **Serious:** *Clostridioides difficile*-associated diarrhea, hypersensitivity reactions (rash, hives, anaphylaxis), hepatitis, cholestatic jaundice (more common in males >60 years).
## Key Drug Interactions
* **Methotrexate:** May decrease renal clearance, increasing systemic toxicity/risk.
* **Warfarin:** Beta-lactams may enhance the anticoagulant effect by altering gut flora (vitamin K synthesis); monitor INR.
* **Oral Contraceptives:** May reduce efficacy; backup contraception is recommended during therapy.
* **Probenecid:** Decreases renal excretion of amoxicillin, increasing serum levels.
## Monitoring
* Monitor for signs of hypersensitivity (rash, anaphylaxis) during the first dose.
* Assess stools for severe/bloody diarrhea (risk of *C. difficile*).
* Monitor long-term therapy for renal, hepatic, and hematopoietic function.
## Clinical Pearls
* **Administration:** Administer with a meal or snack to significantly improve gastrointestinal tolerability.
* **Selection:** The 875 mg tablet contains the same amount of clavulanate as the 500 mg tablet. Do *not* substitute two 250 mg tablets for one 500 mg tablet, as this doubles the clavulanate dose and increases diarrhea risk.
* **Stability:** Keep suspensions refrigerated until use to maintain potency.
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**Disclaimer:** This information is for educational purposes only. Clinical practice guidelines vary by institution and region. Always consult current prescribing information (package insert) and local antibiograms before prescribing or administering medication.
