Avoiding paediatric dosing errors with risperidone

Summary

Risperidone, marketed in Australia under the brand name Risperdal and various generic brands, is a prescription medicine used to treat patients with behavioural disorders.

We received 22 adverse event reports in 2024 involving the overdose of risperidone oral solution in Australian paediatric patients. Most reports involved accidentally administering more than the prescribed dose, leading to adverse effects and hospitalisation of the child. No deaths were reported.

We carried out an investigation and found that these administration errors were often due to:

• misunderstanding of dosing instruction
• incorrect use of the dosing syringe
• administration by alternative caregivers, such as babysitters or an extended family member.

To mitigate the risk, the Product Information (PI) and Consumer Medicines Information (CMI) for Risperdal have been updated, with generics required to align theirs with similar information. The revision includes clearer dosing instructions and illustrations to help ensure correct dosing.

The information updates involve oral solution presentations of risperidone, not tablet or injectable forms.

What health professional should do

Given the increased reports of paediatric dosing error, prescribers and pharmacists are advised to take extra care when counselling risperidone patients or caregivers by:

• ensuring all caregivers are aware of the correct dosing instructions
• providing clear explanation on how to measure the exact dose using the supplied syringe
• reminding caregivers to read the dosing label carefully before administration and confirm their understanding, especially with first-time users.

Background information

In November 2024, we conducted a focused signal investigation following a rise in reports of paediatric dosing errors with risperidone oral solution. The investigation revealed most cases involved accidental administration of 10 times the prescribed dose (for example, 5 mL instead of 0.5 mL). These errors were mainly due to misunderstanding of dosing instructions and incorrect use of the provided dosing syringe.

Paediatric patients are more susceptible to side effects, meaning even a slight overdose of risperidone can cause serious adverse reactions, including:

• drowsiness
• sedation
• fast heart rate (tachycardia)
• low blood pressure (hypotension)
• involuntary movement you cannot control (extrapyramidal symptoms),
• irregular heart rhythm (QT prolongation)
• uncontrollable shaking (convulsions).

In response to the investigation, we required pharmaceutical companies to update their PIs and CMIs for risperidone oral liquids with clearer dosing instruction and visual aids.

Various risperidone products are subsidised under the general schedule of the Pharmaceutical Benefits Scheme.

Adverse events reported to us

A search of our publicly available Database of Adverse Event Notifications (DAEN) on 15 April 2025 for risperidone and MedDRA reaction terms ‘accidental overdose’ and ‘overdose’ returned 29 case reports for patients under 18 years of age. None of these resulted in death.

Importantly, inclusion in the DAEN does not mean the details of the reported event have been confirmed, or that the event has been determined to be related to a medicine.

Updates to the PI

Changes to the risperidone PI are highlighted below (Risperdal is used as the example and all other generic products will be required to align with similar information, however the syringe and instructions may vary across brands so please check individual PI documents):

4.2 DOSE AND METHOD OF ADMINISTRATION

DIRECTIONS FOR OPENING THE BOTTLE AND USING THE PIPETTE FOR THE ORAL SOLUTION:

The solution comes with a syringe (pipette). Use only the pipette that comes with RISPERDAL oral solution for measuring the dose prescribed. Measure the exact dose of medicine you need. Pay attention when measuring a small dose, for example for 0.25 mg, measure 0.25 mL (a quarter millilitre); for 0.5 mg, measure 0.5 mL (half a millilitre).

Figure 1: The bottle comes with a child-resistant cap, and should be opened as follows: Push the plastic screw cap down while turning it anti-clockwise. Remove the unscrewed cap.
Figure 2: Insert the pipette into the bottle.
Figure 3: While holding the bottom ring (Figure 3a), pull the top ring up to the mark that corresponds to the number of millilitres or milligrams you need to give (See examples Figure 3b). Measure the exact dose of medicine you need. Pay attention when measuring a small dose, for example for 0.25 mg, measure 0.25 mL (a quarter millilitre); for 0.5 mg, measure 0.5 mL (half a millilitre). 1 mL of RISPERDAL oral solution contains 1 mg risperidone. The measured volume is printed every 0.25 mL / 0.25 mg on the plunger. Figure 3b shows examples  of prescribed doses and corresponding marks on the plunger.
Figure 4: Holding the bottom ring, remove the entire pipette from the bottle. Empty the pipette into a non-alcoholic drink by sliding the upper ring down. Mineral water, orange juice, coffee and milk are suitable. Do not use tea. Close the bottle. Rinse the pipette with some cold water after use, let it air dry and store it in its case. Use of detergents or extensive rubbing with a cloth may increase the risk of fading or disappearing print.

Disclaimer

Medicines Safety Update is aimed at health professionals. It is intended to provide practical information to health professionals on medicine safety, including emerging safety issues. The information in Medicines Safety Update is necessarily general and is not intended to be a substitute for a health professional's judgment in each case, taking into account the individual circumstances of their patients. Reasonable care has been taken to ensure that the information is accurate and complete at the time of publication. The Australian Government gives no warranty that the information in this document is accurate or complete and shall not be liable for any loss whatsoever due to negligence or otherwise arising from the use of or reliance on this document.

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Medicines Safety Update is written by staff from the Pharmacovigilance Branch.

• Editor: Dr Daniel Dascombe
• Deputy Editor: Aaron Hall
• Contributors: Emma Knott, Rachel Alexander and Albert Cui