Waste of high-cost medicines, such as orphan drugs, is a major problem in healthcare, which leads to excessive costs for treatments. The main objective of this study was to evaluate the impact of a vial-sharing strategy for patisiran, an orphan drug used for the treatment of hereditary transthyretin-mediated amyloidosis, in terms of a reduction in the discarded drug amount and cost savings. The retrospective observational study was conducted in a tertiary referral center (Emilia-Romagna, Italy), between February 2021 and November 2022. Data on drug waste were calculated as "(mg used-mg prescribed)/mg prescribed" for each session. We found a statistically significant (-9.14%, p < 0.001, 95% CI 5.87-12.41) absolute difference in mean discarded drug rates per session based on the study phase (before and after vial-sharing introduction) at the two-sample t-test. The absolute difference corresponded to a percentage decrease in the average reduction in the discarded drug rate with vial sharing of 82.96% per session. On an annual scale, the estimated cost savings was EUR 26,203.80/year for a patient with a standard body weight of 70 kg. In conclusion, we demonstrated that a patisiran vial-sharing program undoubtedly offsets some of the high costs associated with this treatment. We suggest that this easy-to-introduce and cost-effective approach can be applied to the administration of other high-cost drugs.
Keywords: drug compounding; drug day; hATTR amyloidosis; medication waste; orphan drugs; patisiran; pharmaceutical spending; sustainability; vial sharing.