Definition: The definition of a dispensing error developed by Beso et al 2005 was adopted.
Due to the nature of MDS, extra categories of error were developed by the study steering
“One or more deviations from an interpretable written prescription or medication order,
including written modifications to the prescription made by a pharmacist following contact
with the prescriber”.
Data collection: The clinical pharmacists studied the residents’ medicines and checked
these against the medication prescribed. Medicines were identified which had been: • added or omitted erroneously
• packaged to be given at the wrong time (deviation of more than 2 hours) • dispensed in the wrong dose or formulation, or to be given by the wrong route.
Dispensing errors were recorded on a data collection form (Appendix E) and then entered
into the study database. Dispensing errors were classified according to Table 3.5 and were
not mutually exclusive ie there could be more than one dispensing error per item. If a
dispensing error was linked to a prescribing or medication administration error, this was
recorded.
Denominator: The number of opportunities for error was the number of prescription items
dispensed or omitted.
Table 3.5: Types of dispensing error Contents errors
Omission Failure to dispense a prescribed item
Unprescribed
drug
Dispensing a medication that was not prescribed e.g.
supplying a drug that had been discontinued
Drug incorrect
Dispensing a drug that is different to that prescribed. Excludes
changes made following the pharmacist contacting the
prescriber to correct an error
Dose/strength
error
Dispensing a dose unit containing the wrong amount of the
correct drug, without an appropriate adjustment to the dosing
instructions
Formulation
error
Dispensing the correct drug in a dosage form different to that
prescribed. Includes supplying a modified release formulation
when a standard formulation was prescribed
Extra dose(s)
Dispensing a larger quantity of medication to that prescribed.
If a MDS is used it will include where an extra tablet has been
Missing
dose(s)
Dispensing a smaller quantity of medication to that prescribed.
If a MDS is used it will include where a tablet has been left out
of a compartment
Timing error
Dispensing a medication into a MDS at a different time of day
to that prescribed or usually recommended for that drug.
Dispensing medicine in the wrong colour tray or sheet eg
donepezil prescribed at night but dispensed in pink “morning”
tray; warfarin dispensed in white “short course “ or “as
required” tray
Frequency
error
Dispensing a medication into a MDS at a different frequency to
that prescribed. This includes dispensing a drug prescribed to
be taken “when required” into the regular dosing sections of
the MDS
Patient incorrect Dispensing the correct medications but for the wrong patient
Deteriorated
drug
Dispensing a medication that has exceeded its expiry date or
has been stored at a temperature different to that required, or
for which the primary packaging is damaged. N.B: Drugs in a
heat sealed MDS system have a shelf life of 8 weeks Labelling errors
Patient name
incorrect
Omission of the patient’s name or use of a different name to
that on the prescription
Drug name
incorrect
The drug name on the label deviated from that specified by the
prescriber, except where amendments are necessary to conform
to good pharmaceutical practice. Incorrect would include a
modified release product which was not labelled as such
Drug strength
incorrect
Where more than one strength available, the strength on the
label is different to the strength of the drug supplied
Quantity
incorrect
The drug quantity on the label deviated from that specified by
the prescriber, except where amendments are necessary to
conform to good pharmaceutical practice, or where there is a
record of medication owing.
Dosage incorrect
The dosage on the label deviated from that specified by the
prescriber except where amendments are necessary to conform
to good pharmaceutical practice. (eg: substituting a specific
dose or maximum daily dose when prescriber has indicated
“as directed”)
Date incorrect
Omission of the date of dispensing or use of a date different to
that on which the product was dispensed. Note that MDS are
sometimes pre‐packed and if so should have an additional
label which has batch number, original expiry date and date of
dispensing
Route
error/omission
The route has not been stated for medicines which can be
administered via more than one route e.g. eye, ear and nose
Instructions
incorrect
The instructions deviated from those prescribed, except where
amendments are necessary to conform to written local policy
or good pharmaceutical practice
Additional
warning(s)
Omission or use of incorrect additional warnings, according to
professional references (for example the British National
Formulary)
Pharmacy
address
Failure to include the correct name and address of the
supplying pharmacy on the label
No label
Failure to add a dispensing label (eg tube of cream or inhaler;
multiple packs dispensed with only one label on transparent
outer wrap
Other labelling
errors Any other labelling error not included in the above categories Clinical errors
Allergy error Dispensing a drug for which the patient has an allergy and the
pharmacy is aware of the allergy
Contraindication
Dispensing a drug which is contraindicated in that patient and
where the pharmacy could be reasonably expected to have had
knowledge of this e.g. from the other drugs that the patient is
taking
Interaction Dispensing a drug which could result in a serious drug
interaction
Other Any other error not included in the above categories
Linked error Use to record that the dispensing error is linked to another