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Drugs Dictionary: Amoxicillin

Amoxicillin

Trade Name

Amoxil, Moxatag (brand names); generic amoxicillin

Classification

Penicillin antibiotic; aminopenicillin, beta-lactam

Dosage/Route

  • * Dosage:
    •      – Capsules: 250 mg, 500 mg
    •      – Tablets: 500 mg, 875 mg
    •      – Suspension: 125 mg/5 mL, 200 mg/5 mL, 250 mg/5 mL, 400 mg/5 mL
    •      – IV (less common in U.S.): 500 mg, 1 g vials
  • * Route: Oral (PO); intravenous (IV, rare)

Usual Dosage

  • * Adults: 500 mg PO every 8 hours or 875 mg PO every 12 hours; max 4 g/day
  • * Children (>3 months): 25-50 mg/kg/day PO divided q8-12h; max 3 g/day
  • * Severe Infections: Higher doses (e.g., 80-90 mg/kg/day in kids for otitis media)
  • * Duration: 5-14 days (e.g., 10 days for strep throat)

Mechanism of Action

Inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins, disrupting peptidoglycan cross-linking. Bactericidal against susceptible gram-positive (e.g., Streptococcus) and some gram-negative bacteria (e.g., H. influenzae)

Side Effects & Adverse Effects

  • * Side Effects: Nausea, diarrhea, rash
  • * Adverse Effects:
    •      – Hypersensitivity (rash, anaphylaxis; boxed warning for penicillin allergy)
    •      – Clostridioides difficile-associated diarrhea (CDAD)
    •      – Rare: Hematologic (e.g., thrombocytopenia), hepatotoxicity

Nursing Management (Implications & Teachings)

  • * Implications:
    •      – Assess for penicillin allergy (anaphylaxis history) before first dose
    •      – Monitor for diarrhea (CDAD risk) and rash (esp. in mononucleosis—non-allergic rash common)
    •      – Culture/sensitivity before starting if possible (confirm susceptibility)
    •      – Give on empty stomach (1 hr before/2 hr after meals) for best absorption
  • * Teachings:
    •      – Finish full course; don’t skip doses
    •      – Report hives, swelling, or severe diarrhea
    •      – Take with water, not juice; shake suspension well
    •      – Use backup contraception (reduces oral contraceptive efficacy)

Indication for This Patient

  • * Bacterial infections:
    •      – Upper respiratory (e.g., strep throat, sinusitis)
    •      – Ear infections (otitis media)
    •      – Lower respiratory (e.g., pneumonia)
    •      – UTI, skin infections (susceptible organisms)
  • * H. pylori eradication (with PPI and other antibiotics)

Time

  • * Timing: Every 8 or 12 hours (per dose schedule)
  • * Onset: Symptom relief in 1-3 days; full effect after course completion
  • * Duration: 5-14 days, depending on infection

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