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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 synthesis by binding to penicillin-binding proteins (PBPs).
## Primary Indications
Commonly used for acute otitis media (AOM), streptococcal pharyngitis, community-acquired pneumonia, and lower respiratory tract infections caused by susceptible organisms (*S. pneumoniae*, *H. influenzae*, *S. pyogenes*).
## Adult Dosing
* **Mild to Moderate Infections:** 500 mg every 12 hours or 250 mg every 8 hours.
* **Severe Infections:** 875 mg every 12 hours or 500 mg every 8 hours.
* **Maximum Dose:** Generally 3 g/day, though higher doses are used in specific protocols (e.g., *H. pylori* eradication).
## Pediatric Dosing
* **Standard Dose:** 20–45 mg/kg/day divided every 8–12 hours.
* **High-Dose (e.g., AOM, suspected drug-resistant *S. pneumoniae*):** 80–90 mg/kg/day divided every 12 hours.
* **Maximum Dose:** Do not exceed adult maximums. Pediatric doses should be weight-based; confirm weight-per-dose limits with local institutional guidelines.
## Dose Adjustments
* **Renal Impairment:** Reduce dose or increase interval if CrCl < 30 mL/min. No adjustment needed for CrCl > 30 mL/min.
* **Hemodialysis:** Requires supplemental dosing post-dialysis; consult specific renal dosing references.
## Contraindications
* Known hypersensitivity to amoxicillin, penicillins, or any component of the formulation.
* History of anaphylaxis, angioedema, or urticaria with any $\beta$-lactam antibiotic (use with extreme caution or avoid).
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, rash, and mucocutaneous candidiasis.
* **Serious:** Hypersensitivity reactions (anaphylaxis), *Clostridioides difficile*-associated diarrhea (CDAD), and interstitial nephritis.
## Key Drug Interactions
* **Probenecid:** Increases serum concentrations of amoxicillin by decreasing renal tubular secretion.
* **Methotrexate:** Penicillins may decrease the renal clearance of methotrexate, increasing risk of toxicity.
* **Oral Contraceptives:** May theoretically reduce efficacy; consider backup contraception.
* **Warfarin:** Penicillins may potentially alter the INR (monitor if co-administered).
## Monitoring
* **Baseline:** Renal function (BUN/SCr) in patients with known impairment.
* **Ongoing:** Signs of hypersensitivity, gastrointestinal distress (diarrhea), and clinical response to therapy.
## Clinical Pearls
* **Suspension Stability:** Reconstituted oral suspension is stable for 14 days at room temperature or under refrigeration.
* **Allergy Differentiation:** Determine if history includes true IgE-mediated allergy (e.g., hives, anaphylaxis) or non-allergic adverse effects (e.g., gastrointestinal upset, non-pruritic rash).
* **Administration:** Amoxicillin can be taken with or without food.
* **Spectrum:** Amoxicillin does not cover *Staphylococcus aureus* (penicillinase producers) or atypical pathogens.
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*Disclaimer: This information is for educational purposes only. Clinical practice requires verification of current prescribing information, institutional protocols, and patient-specific factors via verified drug references (e.g., Lexicomp, UpToDate) or a clinical pharmacist.*
