Drug compatibility in CSCIs for palliative care

Dickman, 2011 Safer Care Victoria, 2021

When using continuous subcutaneous infusions (CSCIs), 2 or 3 drugs are often administered in combination. It is important to ensure all combinations are compatible before starting the infusion.

Sodium chloride 0.9% is recommended as the diluent in most CSCIs. It is isotonic and produces a solution closer to physiological tonicity than water for injection. However, some drugs (eg cyclizine) are not compatible with sodium chloride 0.9%—consult local healthcare service protocols when setting up a CSCI.

Increasing the number of drugs combined in an infusion increases the likelihood of incompatibility occurring. Local healthcare service protocols may specify a maximum number of drugs that can be used in combination.

Regular monitoring of the solution in the syringe and the tubing is required to detect evidence of physical incompatibility (eg precipitation, colour change). However, incompatibility may be present even without visible evidence.

Useful sources of information for compatibility of drugs in CSCIs include:

Dickman A, Schneider J. The syringe driver. Continuous subcutaneous infusion in palliative care. 4^th ed. Oxford: Oxford University Press; 2016.
Safer Care Victoria. Syringe driver compatibility: Guidance document. 2021. URL

While published information on drug compatibility in CSCIs is often useful, it may not always be applicable to a patient’s situation. For example, compatibility studies are conducted at specific concentrations of individual drugs, and do not necessarily apply to all concentrations used clinically. In addition, most studies are conducted at room temperature and do not provide advice at body temperature.