What is the recommended dose of ertapenem (a carbapenem antibiotic) for a 130-pound adult male with a urinary tract infection (UTI) and no significant renal impairment?

Ertapenem Dosing for UTI in a 130-Pound Male

For a 130-pound (59 kg) adult male with a UTI and normal renal function, administer ertapenem 1 gram intravenously once daily, infused over 30 minutes. 1

Standard Dosing Regimen

• The FDA-approved dose for complicated urinary tract infections (including pyelonephritis) in adults is 1 gram IV once daily 1
• The recommended treatment duration is 10 to 14 days, which may include a switch to appropriate oral therapy after at least 3 days of parenteral therapy once clinical improvement is demonstrated 1
• Ertapenem should be infused over 30 minutes when administered intravenously 1

Weight Considerations

• At 130 pounds (59 kg), this patient falls well within the standard adult dosing range 1
• No weight-based dose adjustment is necessary for adults, as the 1 gram once-daily dose is fixed regardless of body weight for patients with normal renal function 1, 2
• Pediatric patients (3 months to 12 years) receive 15 mg/kg twice daily (not to exceed 1 g/day), but this patient qualifies for adult dosing 1

Renal Function Assessment

Before initiating therapy, assess renal function to determine if dose adjustment is needed: 1

• If creatinine clearance >30 mL/min/1.73 m²: No dose adjustment required - use standard 1 gram daily 1
• If creatinine clearance ≤30 mL/min/1.73 m²: Reduce dose to 500 mg daily 1
• If on hemodialysis: Give 500 mg daily, plus a supplementary 150 mg dose if ertapenem is administered within 6 hours prior to dialysis 1

Clinical Efficacy Data

• Ertapenem demonstrates 89.5% favorable microbiological response rates in complicated UTIs when compared to ceftriaxone 3
• The drug achieves high urinary concentrations (>128 mg/L) at 40% of the dosing interval, providing excellent coverage for uropathogens 4
• Short-course therapy (median 6 days parenteral) achieves 81% clinical cure rates, increasing to 96% when combined with adjunctive fosfomycin 5

Practical Administration Considerations

Critical preparation requirements: 1

• DO NOT mix or co-infuse with other medications 1
• DO NOT use diluents containing dextrose (α-D-glucose) 1
• Reconstitute the 1 g vial with 10 mL of Water for Injection, 0.9% Sodium Chloride Injection, or Bacteriostatic Water for Injection 1
• After reconstitution, transfer to 50 mL of 0.9% Sodium Chloride Injection 1
• Complete the infusion within 6 hours of reconstitution 1

Spectrum and Resistance Considerations

• Ertapenem provides excellent coverage against E. coli and Klebsiella pneumoniae, which account for 64.7% and 9.8% of complicated UTI isolates respectively 3
• The drug retains activity against most strains with AmpC and extended-spectrum beta-lactamases (ESBLs) 6
• Ertapenem is less active against non-fermenters (such as Pseudomonas aeruginosa) compared to other carbapenems 6

Switch to Oral Therapy

After at least 3 days of parenteral therapy and clinical improvement: 1

• Consider switching to an appropriate oral agent (commonly ciprofloxacin was used in clinical trials) 3
• The median duration of parenteral therapy in clinical trials was 4 days, with total therapy duration of 13 days 3
• 96% of patients in efficacy trials were successfully switched to oral therapy 3

Common Pitfalls to Avoid

• Do not use ertapenem empirically for hospital-acquired UTIs where Pseudomonas is suspected, as it lacks adequate coverage against non-fermenters 6
• Avoid dextrose-containing diluents, which can inactivate the drug 1
• Do not administer the intramuscular formulation intravenously - the IM preparation uses lidocaine as a diluent and is not appropriate for IV use 1
• Monitor for drug accumulation if renal function deteriorates during therapy, as ertapenem is primarily renally excreted 1, 2