Background Medication management of older peoples is of special importance regarding to their sensitivity to adverse drugs effects.

Purpose This study compared the medication error rates and the operating costs before and after implementation of an automated unit dose distribution system:

• before: ward stock system (WSS): prescriptions in paper record, medications prepared by nurses in the ward,

• after: computerised physician order entry including electronic medication administration record (eMAR), pharmacist interventions, unit dose delivering system robot, automated medications delivering systems.

Materials and Methods Medication errors were identified using an observation-based method. Pharmacist attended drugs administration rounds in a randomly selected ward section. Administrations were compared to prescriptions. Error rates and error types were compared according to a chi square method. Clinical severity of errors was assessed.

Drug consumptions, costs of pharmaceutical and nursing staffs and equipment were calculated for each period.

Results During the WSS period, 28 rounds were attended (148 patients, 615 drugs administrations) versus 31 rounds (166 patients, 783 drugs administrations) during the UDDS period. The rate of medication errors significantly decreased between the WSS period and the UDDS period (12.6% vs 5.2%). During the WSS period, a medication error occurred by 30.4% of the patients (45 patients) compared to 19.9% (32 patients) during the UDDS period (p < 0.05). Most reduced errors during the UDDS period were wrong dose (16 vs 4) and wrong drug (19 vs 1).

Drugs consumptions decreased of 11,527€ a year (11.5%) and cost of nurses time saved was assessed at 24,642€ a year. One dose delivered by robot cost 0.56€, 0.41€ excluding robot loan. Safety brought by the automated unit dose distribution system cost 90.4€ for one bed a month, including, staff and equipment.

Conclusions Drug safety showed her necessity, this has an additional cost witch must be compared with consequences of medication errors and medicine-related illness.

No conflict of interest.