Pembrolizumab Diluent
Pembrolizumab should be diluted in 0.9% sodium chloride injection (normal saline) or 5% dextrose injection for intravenous infusion 1.
Recommended Diluents
The FDA-approved prescribing information for pembrolizumab (KEYTRUDA) specifies two acceptable diluents 1:
- 0.9% sodium chloride injection (normal saline) - preferred option
- 5% dextrose injection - acceptable alternative
Clinical Guidelines Support
Multiple clinical guidelines consistently reference pembrolizumab administration via intravenous infusion without specifying alternative diluents, implicitly supporting standard saline or dextrose solutions 2, 3. The CSCO colorectal cancer guidelines specifically note pembrolizumab 200mg as "intravenous infusion" 2.
Stability and Compatibility Evidence
Saline is the most extensively studied and recommended diluent:
- Pembrolizumab diluted to 1 mg/mL in normal saline polyolefin bags demonstrates physicochemical stability for at least 1 week at both refrigerated (5°C ± 3°C) and room temperature (20°C ± 3°C) 4
- Extended stability studies show pembrolizumab in saline infusion bags remains stable for up to 4 weeks at 2-8°C plus an additional 2 weeks at ambient temperature 5
- No aggregation or degradation occurs with saline dilution 4
Important caveat regarding dextrose: Research demonstrates that therapeutic monoclonal antibodies formulated at acidic pH (≤6.5) can form insoluble aggregates when mixed with dextrose and human serum 6. While pembrolizumab is approved for use with dextrose, saline represents the safer, more widely validated choice.
Practical Preparation Details
- Final concentration range: Typically diluted to 1-10 mg/mL 1
- Container: Polyolefin infusion bags are appropriate 4
- Storage after dilution: Up to 24 hours at 2-8°C or 6 hours at room temperature per manufacturer; extended stability data supports longer storage under controlled conditions 5, 4
The overwhelming evidence and clinical practice favor 0.9% sodium chloride (normal saline) as the diluent of choice for pembrolizumab infusion.