Prevalence and nature of medication administration errors in health care settings: a systematic review of direct observational evidence.
This systematic review estimates that nearly 1 in 5 medication doses is administered incorrectly in the inpatient setting, although the majority of these errors appear to be administering drugs at the wrong time rather than administering the wrong dose or wrong medication entirely. The review also notes methodological flaws in the medication error literature that have been cited in other studies.