Prednisolone, methadone errors

liquid medicine measuring cup

Liquid doses prescribed in milligrams but dispensed as millilitres can lead to patients being given a dose five times higher than prescribed, says PDL

Typically this time of year sees an increase in the number of incidents reported to PDL involving prednisolone liquid.

Late winter to early spring is a common time for patients to present with croup and asthma, says PDL.

Prednisolone liquid may be prescribed in milligrams, as the products contain prednisolone 5mg/ml.

A dose prescribed in milligrams but dispensed as millilitres leads to a patient being given a dose five times higher than prescribed, emphasises PDL.

Often the patients are young children.

Case Scenario

An 11-month-old child was prescribed prednisolone 11mg daily for three days. The directions were incorrectly entered as 11mls and labelled as such.

The infant was given this dose by the parents who then became concerned about the large volume. They contacted the hospital to confirm the dose.

The error was identified, and the child did not experience any significant side effects from the incorrect dosage.

While there was no harm in this case, reports to PDL indicate the likelihood of a formal complaint is greater when an error involves a child.


Methadone liquid is also often involved in mg/ml errors, whereby the dose is prescribed in milligrams and measured in millilitres.

Several factors have been identified as a cause of this error including:

  • Familiarity of the client and repetitive dispensing
  • Distraction by clients and others at the time of measuring the dose
  • Multiple clients receiving the medicine daily, and
  • The involvement of locums, or other pharmacists less familiar with the process.

The product is available in 5mg/ml and the error risk is significant at five times that prescribed.

Follow the steps below to help ensure a robust system is in place to minimise the likelihood of an error occurring:

  1. Request contact details from those receiving methadone treatment, including a next of kin, with reassurance the details will only be used in case of an emergency.
  2. Familiarise yourself with your State or Territory guidelines regarding management of overdose.

Other commonly reported errors involving mg and ml to be mindful of include Ranitidine liquid 15mg/ml and omeprazole suspension compounded in various concentrations, says PDL.

Call 1300 854 838 if this topic raises any concerns for you. PDL membership includes 24/7 access to speak with a Professional Officer for immediate advice and incident support, Australia wide.

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