What is the recommended dosage and treatment duration of Meropenem (generic name) for complicated urinary tract infections (UTIs) and pulmonary infections?

Meropenem Dosing for Complicated UTIs and Pulmonary Infections

For complicated urinary tract infections (UTIs), meropenem should be administered at 1 gram IV every 8 hours for 5-7 days, while for pulmonary infections, meropenem should be administered at 1 gram IV every 8 hours for at least 7 days. 1, 2

Dosing for Complicated UTIs

Standard Dosing

• Meropenem 1 gram IV every 8 hours 2
• Duration: 5-7 days 1
• Administration: IV infusion over 15-30 minutes or as IV bolus over 3-5 minutes 2

Special Populations - Renal Impairment

Dosage adjustment based on creatinine clearance:

• CrCl >50 mL/min: 1 gram every 8 hours
• CrCl 26-50 mL/min: 1 gram every 12 hours
• CrCl 10-25 mL/min: 0.5 gram every 12 hours
• CrCl <10 mL/min: 0.5 gram every 24 hours 2

Pediatric Dosing

• Children ≥3 months: 20 mg/kg every 8 hours (maximum 1 gram per dose) 2
• Children <3 months with normal renal function:
  • <32 weeks gestational age, <2 weeks postnatal age: 20 mg/kg every 12 hours
  • <32 weeks gestational age, ≥2 weeks postnatal age: 20 mg/kg every 8 hours
  • ≥32 weeks gestational age, <2 weeks postnatal age: 20 mg/kg every 8 hours
  • ≥32 weeks gestational age, ≥2 weeks postnatal age: 30 mg/kg every 8 hours 2

Dosing for Pulmonary Infections

Standard Dosing

• Meropenem 1 gram IV every 8 hours 2, 3
• Duration: At least 7 days 1
• For Pseudomonas aeruginosa infections: 1 gram every 8 hours is specifically recommended 2

Alternative Treatment Options for MDR Pathogens

For Carbapenem-Resistant Enterobacterales (CRE)

If treating CRE infections, consider:

• Ceftazidime-avibactam 2.5 g IV q8h (weak recommendation, very low quality evidence) 1
• Meropenem-vaborbactam 4 g IV q8h (weak recommendation, low quality evidence) 1, 4
• Imipenem-cilastatin-relebactam 1.25 g IV q6h (weak recommendation, low quality evidence) 1

For Vancomycin-Resistant Enterococci (VRE)

For VRE pulmonary infections:

• Linezolid 600 mg IV q12h (strong recommendation, low quality evidence) for at least 7 days 1

Clinical Considerations

Efficacy

• Meropenem has demonstrated high clinical efficacy (93-100%) in the treatment of complicated UTIs 5
• For pulmonary infections, meropenem shows similar efficacy to other antibiotics including imipenem/cilastatin 3
• In severe complicated UTIs, meropenem has shown clinical efficacy in 100% of cases with bacteriological efficacy of 88.9% 6

Monitoring

• Assess clinical response within 48-72 hours of treatment initiation
• Follow-up urine culture may be warranted in complicated cases or treatment failures
• Monitor renal function during therapy, especially in patients requiring dosage adjustments

Common Pitfalls and Caveats

1. Failure to adjust dose in renal impairment: Always calculate creatinine clearance and adjust dosing accordingly to prevent toxicity.
2. Inadequate duration of therapy: Ensure complete course of antibiotics (5-7 days for UTIs, at least 7 days for pulmonary infections).
3. Inappropriate use for resistant organisms: Check susceptibility testing when available, especially for suspected CRE or other MDR pathogens.
4. Extended infusion benefit: Consider extended infusion (over 3 hours) when treating organisms with higher MICs, particularly for Pseudomonas aeruginosa.
5. Missed opportunity for oral step-down: Evaluate for potential oral step-down therapy after clinical improvement to reduce IV access complications.

Meropenem remains an important option for the empirical treatment of serious bacterial infections in hospitalized patients, with a broad spectrum of activity against both Gram-positive and Gram-negative pathogens, including ESBL-producing Enterobacteriaceae 3.