Background A 10-fold error occurred in our hospital when multiple vials were used to prepare a single dose of an injectable medicine. We aimed to prevent future similar errors and proposed and tested a ‘1 vial rule’.

Purpose To compare paediatric injectable drug doses with available products; to identify doses which could be administered using a single ampoule or vial; and to determine the feasibility of a ‘1 vial rule’.

Material and methods This study did not require ethics approval. Electronic prescriptions were screened on 1 day in January 2015. Each prescribed dose of injectable medicines was recorded. The number of vials needed to prepare the dose was calculated. For each dose we determined whether a single vial could be used. For all options, we calculated the excess drug in the vial. We determined the extent to which a ‘1 vial rule’ could apply.

Results 169 prescriptions for 48 different injectable medicines were observed. 70% (119/169) of doses could be administered using the smallest vial available. 50 doses needed multiple vials, including 20 doses requiring 3 or more vials. Using larger vial sizes, 95% (160/69) of doses could be administered using a single vial. For 32/50 of doses, the excess drug available was unchanged. For 8/50 prescriptions, only 1 vial size of the drug was available.

For 10 prescriptions for 6 drugs using larger vials resulted in greater excess of drug being available than with smaller vials, increasing the potential for overdose.

Conclusion Most injectable doses prescribed could be administered using a single vial if the vial size nearest the dose was used. A ‘1 vial’ rule applies to 95% of paediatric injectable doses. Using more than 1 vial alerts staff that correct doses may be exceeded, prompting staff to double check prescriptions and dose or volume calculations. The rule has been successfully accepted and promoted across our paediatric unit as an error prevention strategy.

References and/or acknowledgements Chappell K, Newman C. Potential tenfold drug overdoses on a neonatal unit. Arch Dis Child Fetal Neonatal Ed2004;89:F483–4. doi: 10.1136/adc.2003.041608