Assessment of final product dosing accuracy when using volumetric technique in the preparation of chemotherapy

Studies have compared gravimetric and volumetric dosing accuracies in chemotherapy agents, finding high accuracy in gravimetric measurements with a mean deviation of ± 0.06%, while volumetric measurements had a mean deviation of ± 3.02%.

Chemotherapy doses prepared under a biological safety cabinet containing two weights from the precision scale between 15 December 2010 and 30 March 2011 were eligible for inclusion. Empty syringes attached to a closed-system transfer device were weighed prior to product manipulation. The product was then prepared using the syringe pull-back method (volumetric technique) and the same syringe containing drug was weighed (gravimetric method).

A total of 1156 compounded sterile products were eligible for the study. The mean percent volume difference of preparations included was -0.53% with a range of -64.9% to 94.22% for individual doses. Of the prepared doses, 71.7% were within ± 5% and 87.4% were within ± 10% of the ordered dose. Secondary outcomes found to be associated with an increased percent volume difference were the pediatric population, smaller volumes prepared, drugs requiring reconstitution compared to already in solution, and final product dispensed to the patient in syringes.

While the mean value of volumetric measurements is within the generally understood acceptable range for dispensing chemotherapy, the range of measurements is highly variable. Future studies are warranted to better understand the reasons behind the variation and to evaluate the impact of workflow changes on improving final product accuracy.