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# Drug Information Request: Amoxicillin
## Overview
Amoxicillin is a beta-lactam aminopenicillin antibiotic that inhibits bacterial cell wall synthesis. It is stable in the presence of gastric acid and provides broader coverage than penicillin G.
## Primary Indications
* Acute otitis media
* Community-acquired pneumonia
* Pharyngitis/Tonsillitis (Group A Strep)
* Sinusitis
* *H. pylori* eradication (in combination therapy)
## Adult Dosing
* **Mild to Moderate Infections:** 250 mg to 500 mg orally every 8 hours, or 500 mg to 875 mg every 12 hours.
* **Severe Infections:** 875 mg orally every 12 hours.
* **Maximum Dose:** Generally 1.75 g/day (standard); up to 3 g/day in specific protocols (e.g., *H. pylori* or early Lyme disease).
## Pediatric Dosing
* **General Infections:** 20–40 mg/kg/day in divided doses every 8 hours, or 25–45 mg/kg/day in divided doses every 12 hours.
* **Acute Otitis Media (High-Dose):** 80–90 mg/kg/day in 2 divided doses.
* **Maximum Dose:** Should not exceed the adult maximum dose.
## Dose Adjustments
* **Renal Impairment:** Requires adjustment in severe renal insufficiency. If CrCl is 10–30 mL/min, use 250–500 mg every 12 hours. If CrCl <10 mL/min, use 250–500 mg every 24 hours.
## Contraindications
* Known hypersensitivity to amoxicillin or any penicillin.
* History of severe allergic reactions (e.g., anaphylaxis, Stevens-Johnson syndrome) to any beta-lactam.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, rash.
* **Serious:** *Clostridioides difficile*-associated diarrhea, hypersensitivity reactions (anaphylaxis), Jarisch-Herxheimer reaction (if treating Lyme).
## Key Drug Interactions
* **Probenecid:** Decreases renal tubular secretion of amoxicillin, increasing serum levels.
* **Methotrexate:** Penicillins may decrease renal clearance, potentially increasing methotrexate toxicity.
* **Warfarin:** Beta-lactams may rarely increase INR; monitor if on long-term therapy.
* **Live Oral Typhoid Vaccine:** Antibiotics may interfere with the immune response; avoid concurrent use.
## Monitoring
* Monitor for signs of hypersensitivity (rash, urticaria, wheezing).
* Assess renal function periodically in patients on long-term or high-dose therapy.
* Monitor stool frequency to screen for *C. difficile* infection.
## Clinical Pearls
* Amoxicillin is generally preferred over ampicillin for oral administration due to superior absorption and fewer gastrointestinal side effects.
* Does not possess beta-lactamase activity; ineffective against *Staphylococcus aureus* or beta-lactamase-producing *H. influenzae/M. catarrhalis*.
* For suspected penicillin-resistant *S. pneumoniae* in otitis media or high-dose scenarios, consider consulting local antibiograms or infectious disease protocols.
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**Disclaimer:** This information is provided for educational purposes and reflects general clinical knowledge. Always verify current prescribing information, institutional protocols, and patient-specific factors before administering any medication.
