Development and feasibility assessment of an in-house gravimetric control system for quality assurance of antineoplastic compounding

Background Gravimetric control is an objective quality assurance strategy for detecting compounding errors in antineoplastic preparations. However, implementation remains inconsistent across hospital pharmacies, particularly in resource-limited settings. Objectives To develop, and preliminarily assess the feasibility, in a pilot study, of an in-house gravimetric control system for routine quality control of antineoplastic preparations in a hospital chemotherapy compounding unit. Methods A descriptive cross-sectional observational study was conducted in a Portuguese hospital between February and March 2024. Antineoplastic preparations compounded in syringes, infusion bags, or pumps were included. Drug densities were determined experimentally using a semi-analytical precision scale. Syringe dead-space-correction was calculated where applicable. A semi-automated Microsoft Excel ® -based gravimetric control system was developed to calculate expected mass and percentage deviation between expected and measured mass. Deviations ≤5% were considered acceptable. Method applicability was assessed in 47 preparations from 11 different drugs. Results Density coefficients of variation were consistently low across drugs and container types, supporting measurement precision and solution homogeneity. Differences between measured and dead-space-corrected densities were minimal (mean difference 0.006 g/mL; SD 0.004), indicating negligible practical impact. During applicability testing (n = 47), percentage errors ranged from 0.04% to 2.31%, all within the predefined ±5% acceptance threshold. No preparation required rejection. Conclusions In this pilot study, the developed gravimetric control system proved to be practical, affordable, and reliable for routine quality control of chemotherapy preparations. The Excel ® -based gravimetric control system allows rapid implementation without specialized software and may support standardization of compounding verification processes across hospital pharmacies. Wider inter-institutional validation is warranted.