Background Difficulties with drug supply is a global problem, creating local problems, such as undesirable drug changes.

Compared with other drugs, changing cytostatics for chemotherapy creates significantly more problems, including extra paperwork, quality control, quality assurance, updated production documentation and workflow. In order to decrease the number of cytostatic drug changes, an increase in buffer stock of 23 mature cytostatic products with low price (60 item numbers) was implemented at a national level. The buffer stock was increased from 2 weeks to 2 months (expected consumption).

Purpose The aim of this study was to evaluate the effects and investments of the increased buffer stock of 23 cytostatics at the hospital pharmacies.

Material and methods Quantitative method the number of difficulties with supply were recorded together with the number and types of drug changes, before and after the buffer stock increase. Qualitative method: a questionnaire was sent to all hospital pharmacies (n=8) elucidating investments and level of challenges related to cytostatic changes.

Results With 2 weeks buffer stock (year 2013): 57% of cytostatics with supply difficulties resulted in a drug change.

Types of changes recorded: alternative package size, known supplier, new supplier or unlicensed product.

8 of 12 suppliers of cytostatics had supply difficulties that resulted in a drug change.

With 2 months buffer stock (year 2015): 41% of cytostatics with supply difficulties resulted in a drug change. Types of changes recorded: alternative package size or known supplier. No changes to new supplier or unlicensed product. 3 of 11 suppliers of cytostatics had supply difficulties that resulted in a drug change. Total investment in extra storage capacity: €1100/1 million inhabitants (excluding drug investments). Despite a reduction in cytostatic changes, the hospital pharmacies still found that drug changes in cytostatic created stressful situations.

Conclusion Increased buffer stock of cytostatics from 2 weeks to 2 months: was shown to be effective in order to reduce the number of drug changes; cannot eliminate drug changes; does not require large investments in extra storage capacity; does not remove the stress and extra work when a drug change is necessary; reduced the complexity of the drug changes; and reduced the number of suppliers who had supply difficulties that resulted in a drug change.

No conflict of interest