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# Drug Information Request: Amoxicillin
## Overview
Amoxicillin is a moderate-spectrum, bactericidal $\beta$-lactam antibiotic of the penicillin class. It inhibits bacterial cell wall biosynthesis by binding to penicillin-binding proteins (PBPs).
## Primary Indications
Commonly used for acute otitis media, streptococcal pharyngitis, community-acquired pneumonia, and *H. pylori* eradication.
## Adult Dosing
* **Mild to Moderate Infections:** 500 mg orally every 12 hours or 250 mg every 8 hours.
* **Severe Infections:** 875 mg orally every 12 hours or 500 mg every 8 hours.
* **Max Dose:** Generally 1.5–3 g daily, though higher doses are used in specific infectious disease protocols.
## Pediatric Dosing
* **Standard Dose:** 20–45 mg/kg/day orally in divided doses every 8–12 hours.
* **Acute Otitis Media (High Dose):** 80–90 mg/kg/day orally in divided doses every 12 hours.
* **Max Pediatric Dose:** Should not exceed the maximum recommended adult dose unless directed by specific guidelines (e.g., IDSA/AAP).
## Dose Adjustments
* **Renal Impairment:**
* CrCl 10–30 mL/min: 250–500 mg every 12 hours.
* CrCl <10 mL/min: 250–500 mg every 24 hours.
* **Hepatic Impairment:** No standard adjustment required, but use with caution.
## Contraindications
* History of severe allergic reaction (e.g., anaphylaxis, Stevens-Johnson syndrome) to any penicillin or $\beta$-lactam.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, rash.
* **Serious:** *Clostridioides difficile*-associated diarrhea, anaphylaxis, seizure (with extreme overdose/renal failure).
## Key Drug Interactions
* **Probenecid:** Decreases renal tubular secretion of amoxicillin, increasing serum levels.
* **Methotrexate:** May decrease renal clearance, increasing risk of toxicity.
* **Warfarin:** May slightly increase INR; monitor patients on anticoagulation.
* **Oral Contraceptives:** Potential for decreased efficacy (controversial; data is limited).
## Monitoring
* Monitor for signs of hypersensitivity (rash, wheezing).
* Monitor renal function in patients on long-term therapy or with pre-existing impairment.
* Monitor for persistent diarrhea (risk of *C. diff*).
## Clinical Pearls
* Amoxicillin is stable in the presence of gastric acid.
* It is not effective against $\beta$-lactamase-producing bacteria (e.g., *Staphylococcus aureus* or *H. influenzae* producing $\beta$-lactamase); consider amoxicillin-clavulanate in those cases.
* Amoxicillin suspension should be discarded after 14 days; check the manufacturer’s specific expiration label.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical guidelines and local antimicrobial susceptibility patterns must be consulted before prescribing. Verify all dosing, compatibility, and contraindications using institutional protocols, the package insert, or professional clinical resources (e.g., Lexicomp, UpToDate) prior to administration.
