What is the recommended method for administering meropenem (generic name) for a 3-hour infusion?

Meropenem 3-Hour Extended Infusion Administration

For meropenem administered as a 3-hour extended infusion, reconstitute the dose (typically 1-2 grams) and add the complete solution to 100 mL normal saline, then infuse over 3 hours. 1

Reconstitution and Preparation

• Reconstitute meropenem vials according to manufacturer instructions first, then add the entire reconstituted solution to 100 mL of 0.9% normal saline for the extended infusion 2, 1
• The final concentration should not exceed 50 mg/mL when diluted in normal saline 3
• Prepare the solution immediately before administration due to stability concerns 3, 4

Infusion Parameters

• Administer the complete 100 mL solution as a continuous infusion over exactly 3 hours 1
• Extended infusion over 3 hours is specifically recommended for carbapenem-resistant Enterobacteriaceae (CRE) infections or when the minimum inhibitory concentration (MIC) is ≥8 mg/L 1
• This prolonged infusion maximizes the time that meropenem concentrations remain above the MIC, which is the critical pharmacodynamic parameter for efficacy 3, 5

Dosing Regimens

• Standard dose: 1 gram IV every 8 hours via 3-hour infusion for most serious infections 2, 1
• High dose: 2 grams IV every 8 hours via 3-hour infusion for severe pneumonia, high MIC organisms (≥16 mg/L), or KPC-producing organisms 1
• No loading dose is required for meropenem regardless of infection severity 1

Stability Considerations

• Critical limitation: Meropenem concentrations in normal saline at room temperature (22°C) decrease to 90% of initial concentration at approximately 7.4 hours 3
• At higher temperatures (32-37°C), degradation accelerates with only 5.7 hours until 90% concentration is reached 3
• The 3-hour infusion time is well within the stability window, ensuring adequate drug concentration throughout administration 3, 4
• Do not prepare solutions more than 1-2 hours before administration 3

Administration Technique

• Use a dedicated IV line or flush other medications before and after meropenem infusion 2
• Administer through a filter if crystals are visible (though this is uncommon with proper reconstitution) 2
• Monitor the infusion pump to ensure the complete 100 mL infuses over the full 3-hour period 1

Clinical Scenarios Requiring 3-Hour Infusion

• Hospital-acquired or ventilator-associated pneumonia with Pseudomonas aeruginosa or Acinetobacter species 2
• Critically ill patients with healthcare-associated infections requiring optimized pharmacodynamics 2, 1
• Infections caused by organisms with elevated MIC values (≥8 mg/L) 1
• Carbapenem-resistant Enterobacteriaceae infections as part of combination therapy 1

Common Pitfalls to Avoid

• Do not use 24-hour continuous infusion: Meropenem degrades significantly beyond 8 hours at room temperature, making 24-hour infusions inappropriate 3, 4
• Do not administer as a rapid bolus: Standard 15-30 minute infusions are acceptable for susceptible organisms, but extended infusion is superior for resistant pathogens 1
• Do not mix with other medications: Meropenem should be administered separately due to compatibility concerns 2
• Do not store reconstituted solutions: Prepare fresh for each dose due to rapid degradation 3, 4