Background
Medication errors (ME) threaten safety of drug usage. Over the last decade interest in ME has increased. However, most studies investigate oral ME. Comparison of countries and different health services is rare.

Aim
To compare preparation and administration of intravenous (iv) drugs in two countries and three pharmacy services and to investigate iv drug preparation and administration errors.

Setting
Two wards in each of three teaching hospitals: one with a traditional British ward pharmacy service (TBP) and two hospitals in Germany, one with a traditional ward stock supply (TGP) and one with a satellite pharmacy service (GSP).

Method
The preparation and administration of iv drugs were observed and details recorded. An error was defined as any discrepancy between preparation and administration and original prescription or the manufacturer's instructions. Iv doses to be administered over 24 hours and medication to be given as required were excluded from the analysis. The proportion of error per dose prepared, administered and omitted was calculated respectively. The clinical significance of errors was scored using an objective method of severity assessment.

Results
A total of 299 preparations and 278 administrations were observed. There was no statistical significance between the overall proportion of errors found for the three services: Preparation/ administration error rates for the TBP were 0.23/055, for the TGP were 0.24/0.55 and for the GSP 0.33/0.42. However, the most common errors in TBP were omissions, whereas dose errors dominated in the German pharmacy services. Also there were differences between the pharmacy services regarding the classes of drugs involved in the same type of errors. The majority of errors were likely to be associated with a "moderate" to "severe" outcome.

Conclusion
Differences in preparation and administration of iv drugs were identified between the three countries, which influenced the number and types of errors. Careful drug chart reading could possibly reduce omission errors in the TBP. Errors identified in the TGP could possibly be prevented if a daily prescription review by pharmacists was offered. Multiple transcriptions of prescriptions were identified as problematic in the GSP. Further research is needed to develop common definitions of errors, which enable comparison between different countries.