What is the recommended duration of treatment with IM Invanz (Ertapenem) for urinary tract infections (UTIs)?

Duration of Treatment with IM Invanz (Ertapenem) for UTI

For complicated urinary tract infections including pyelonephritis, IM Invanz (ertapenem) should be administered for up to 7 days, with a total treatment duration (including oral step-down therapy) of 10-14 days. 1

Dosing Recommendations

Adults and Adolescents (13 years and older):

• 1 gram IM once daily 1
• Maximum duration for IM administration: 7 days 1
• Total treatment duration (including oral step-down therapy): 10-14 days 1

Children (3 months to 12 years):

• 15 mg/kg twice daily (not to exceed 1 g/day) 1
• Similar duration guidelines apply 1

Treatment Algorithm

1. Initial Assessment:

   • Determine if UTI is complicated (includes pyelonephritis, UTI in men, or UTI with obstruction/foreign body)
   • Obtain urine culture before starting therapy

2. IM Administration:

   • Reconstitute 1g vial with appropriate diluent for IM administration 1
   • Administer once daily at the same time each day

3. Duration Decision Points:

   • Parenteral (IM) phase: Up to 7 days 1
   • Clinical improvement: After ≥3 days of parenteral therapy, consider switching to appropriate oral therapy based on culture results 2
   • Total treatment duration: Complete 10-14 days of combined parenteral and oral therapy 1

4. Monitoring:

   • Assess clinical response within 48-72 hours 3
   • Monitor for adverse effects (rash, diarrhea, nausea occur in approximately 1-5% of patients) 3

Evidence Summary

The FDA-approved labeling for ertapenem clearly states that when administered intramuscularly, ertapenem may be used for up to 7 days 1. For complicated UTIs, the total recommended treatment duration (including parenteral and oral therapy) is 10-14 days 1.

Clinical studies support this approach. In a combined analysis of two randomized trials comparing ertapenem to ceftriaxone for complicated UTIs, patients received a median of 4 days of parenteral therapy followed by oral therapy (usually ciprofloxacin) for a total treatment duration of approximately 13 days, with excellent clinical outcomes (89.5% favorable response) 2.

Another study in Korean adults with acute pyelonephritis and complicated UTIs found that patients treated with ertapenem for a mean duration of 5.6 days of parenteral therapy followed by oral therapy for a total of 13.8 days had favorable microbiological responses in 87.9% of cases 4.

Special Considerations

Renal Impairment

• For adults with severe renal impairment (creatinine clearance ≤30 mL/min/1.73 m²), reduce dose to 500 mg daily 1
• Supplementary dose of 150 mg is recommended if administered within 6 hours prior to hemodialysis 1

ESBL-Producing Organisms

• Ertapenem has shown high efficacy against ESBL-producing bacteria in complicated UTIs 5
• In pediatric studies, treatment durations of approximately 8-9 days were effective for ESBL-producing UTIs 6, 5

Shorter Course Considerations

• Some evidence suggests that shorter courses (median 6 days) of ertapenem may be effective for complicated UTIs in outpatient parenteral antimicrobial therapy settings, particularly when followed by oral therapy such as fosfomycin 7
• However, the FDA-approved duration and strongest evidence support the 10-14 day total treatment course 1

Common Pitfalls to Avoid

• Do not exceed 7 days for intramuscular administration of ertapenem 1
• Do not mix or co-infuse ertapenem with other medications 1
• Do not use diluents containing dextrose for reconstitution 1
• Avoid using ertapenem without obtaining cultures when possible, as this supports antimicrobial stewardship 3
• Remember that ertapenem must be reconstituted prior to administration 1