What is the dosing for Merrem (meropenem) in treating infections that cause leukocytosis?

Meropenem Dosing for Infections Causing Leukocytosis

For adults with normal renal function and serious infections causing leukocytosis, administer meropenem 1 gram IV every 8 hours as a 15-30 minute infusion, with extended 3-hour infusions recommended when treating resistant organisms with MIC ≥8 mg/L. 1, 2

Standard Dosing for Adults with Normal Renal Function

• Administer 1 gram IV every 8 hours for serious infections including complicated intra-abdominal infections and healthcare-associated infections that commonly present with leukocytosis 3, 2
• For complicated skin and skin structure infections, 500 mg every 8 hours is adequate unless Pseudomonas aeruginosa is suspected, which requires 1 gram every 8 hours 2
• Standard infusion time is 15-30 minutes, though 1 gram doses may be given as IV bolus over 3-5 minutes 2

Extended Infusion Strategy for Resistant Pathogens

• Use extended 3-hour infusions when treating organisms with MIC ≥8 mg/L to maximize time above MIC (T>MIC) and optimize pharmacodynamic properties 1
• For carbapenem-resistant Enterobacterales with meropenem MIC ≥8 mg/L, specifically use 1 gram every 8 hours as a 3-hour infusion 4
• This extended infusion strategy is critical even in patients with renal impairment when treating high-MIC organisms 4

Dosing in Renal Impairment

Reduce dosing frequency based on creatinine clearance thresholds:

• CrCl >50 mL/min: Full dose (500 mg or 1 gram) every 8 hours 2
• CrCl 26-50 mL/min: Full dose every 12 hours 2
• CrCl 10-25 mL/min: Half the recommended dose every 12 hours 2
• CrCl <10 mL/min: Half the recommended dose every 24 hours 2

Special Populations Requiring Modified Dosing

Continuous Renal Replacement Therapy (CRRT):

• Administer 1 gram every 8 hours to compensate for continuous drug removal, as CRRT removes 25-50% of meropenem 4, 5
• Therapeutic drug monitoring is strongly recommended in critically ill patients on CRRT 4
• Research demonstrates that 1 gram every 8 hours achieves adequate trough levels (6.6 ± 1.5 mcg/mL after 6 hours) in patients undergoing CVVH 5

Sustained Low-Efficiency Dialysis (SLED):

• Maintain the full 1 gram dose every 12 hours to preserve concentration-dependent killing 4
• Do not reduce individual doses below 1 gram, as smaller doses may reduce efficacy 4

Intermittent Hemodialysis:

• Approximately 50% of meropenem is removed by hemodialysis 4
• Administer doses after dialysis sessions to avoid premature drug removal and ensure adequate exposure 3, 4

Treatment Duration

• Limit therapy to 5-7 days for complicated intra-abdominal infections and complicated urinary tract infections when adequate source control is achieved 1
• For bloodstream infections causing leukocytosis, treat for 7-14 days 1
• Inadequate source control negates antibiotic efficacy; surgical intervention or drainage is mandatory for intra-abdominal infections 1

Critical Pitfalls to Avoid

• Never use standard dosing for high-MIC organisms (≥8 mg/L) without extending the infusion to 3 hours 1
• Never administer meropenem before dialysis sessions, as this leads to premature drug removal and subtherapeutic levels 4
• Monitor for neurological toxicity when trough concentrations exceed 64 mg/L, particularly in renal impairment 4
• Consider therapeutic drug monitoring in critically ill patients with renal impairment to ensure adequate exposure 4

Pediatric Dosing (3 Months and Older)

• 20 mg/kg every 8 hours (maximum 1 gram) for complicated intra-abdominal infections 2
• 10 mg/kg every 8 hours (maximum 500 mg) for complicated skin infections 2
• For P. aeruginosa infections, use 20 mg/kg every 8 hours 2