Compatibility of medication admixtures in continuous subcutaneous infusions: prioritizing laboratory testing for common combinations.

Objectives: Continuous subcutaneous infusions (CSCIs) are indicated as an alternative therapy when the oral route is not viable. However, despite their widespread use in palliative care, the evidence for admixture compatibility remains a limitation. It is estimated that a significant number of admixtures used in practice are not supported by laboratory studies, which may lead to suboptimal clinical outcomes. The study aimed to determine the frequency of admixtures used in clinical practice without compatibility data generated by laboratory studies, and thereby identifying the most commonly prescribed admixtures that require laboratory data, which can help to guide the prioritization of future testing.

Methods: This study was conducted across five palliative care services (three inpatients and two communities) in Victoria, Australia between May and July 2021. Electronic or paper medication charts of CSCIs were reviewed across all participating sites for all infusions administered. Data collected included medication combinations, dose, diluent, final volume, duration of infusion, reports of infusion-related reactions, and observed incompatibility.

Key findings: A total of 616 infusions containing two to three medications were assessed. Only 60% of these infusions were validated by laboratory data. Eleven most commonly prescribed admixtures with no laboratory compatibility data were identified over the 3-month period.

Conclusion: Laboratory testing for the identified admixtures should be advocated to promote the safe and effective use of these medications.