What is the typical dosage of amoxicillin (a type of penicillin antibiotic) for a adult patient with normal renal function and no known allergy to penicillin?

Amoxicillin Dosing for Adults with Normal Renal Function

For adults with normal renal function and no penicillin allergy, the standard amoxicillin dosage is 750 to 1750 mg/day divided every 8 to 12 hours, with specific dosing dependent on the infection being treated. 1

Standard Dosing Regimens by Indication

General Infections

• Standard adult dose: 250-500 mg every 8 hours or 500-875 mg every 12 hours 1
• The FDA-approved range spans 750-1750 mg/day in divided doses 1
• Dosing frequency can be either every 8 or 12 hours depending on severity and infection type 1

Specific Clinical Scenarios

Skin and Soft Tissue Infections (Impetigo)

• 875 mg twice daily (amoxicillin/clavulanate formulation) 2
• Alternative: 25 mg/kg/day in divided doses for pediatric dosing equivalents 2

Infective Endocarditis Prophylaxis

• 2 grams orally 1 hour before dental procedures for patients at high risk 2
• This is the standard prophylactic dose recommended by the American Heart Association 2

H. pylori Eradication

• Triple therapy: 1 gram twice daily (every 12 hours) combined with 500 mg clarithromycin and 30 mg lansoprazole for 14 days 1
• Dual therapy: 1 gram three times daily (every 8 hours) with 30 mg lansoprazole for 14 days 1

Urinary Tract Infections

• Bladder infections: 250 mg three times daily for 7 days 3
• Renal infections: 500 mg three times daily for 14 days 3
• Single-dose therapy of 3 grams has shown 74% cure rates for uncomplicated UTIs, though conventional courses remain standard 4

Critical Dosing Considerations

Renal Impairment Adjustments

• Dose reduction is required when GFR falls below 30 mL/min 1
• Half-life increases from 71 minutes (normal function) to 16 hours in anephric patients 5
• For patients on hemodialysis, a single 250 mg dose provides adequate levels for 24 hours when given post-dialysis 6
• The serum half-life correlates highly (r=0.967) with creatinine clearance 5

Timing and Administration

• Amoxicillin can be taken with or without food, as absorption is not significantly affected 1
• For surgical prophylaxis, administration should occur within 60 minutes before incision 2
• For endocarditis prophylaxis, give exactly 1 hour before the procedure 2

Common Pitfalls to Avoid

• Do not use standard dosing in severe renal impairment without adjustment—this leads to drug accumulation and toxicity risk 1, 5
• Avoid underdosing in serious infections—the upper range (1750 mg/day) exists for more severe or resistant infections 1
• Do not confuse amoxicillin with amoxicillin/clavulanate dosing—the combination product has different dosing due to the clavulanate component 2
• Recognize treatment failures early—if the organism is amoxicillin-resistant, clinical failure occurs rapidly and alternative therapy is needed 3