New data act as a reminder about accidental poisoning in children

The most common substance category in PIC calls is ‘non-opioid analgesics, antipyretics and antirheumatics’, accounting for one in three cases of pharmacological poisoning.¹

These accidental poisonings primarily involve medicines containing paracetamol (eg, Panadol, Panamax, Dymadon) and medicines containing ibuprofen (eg, Nurofen, Brufen, Advil). Accidental poisoning with these agents can occur in a variety of ways, including dosing errors and exploratory ingestion of syrups and tablets.

While therapeutic doses of paracetamol are safe, unintentional exposure at a high dose results in severe toxic effects. In fact, paracetamol overdose is the leading cause of paediatric acute liver failure in Australia and New Zealand, with another study showing that 14 of 54 cases of acute liver failure were attributed to paracetamol.² These children received excess paracetamol for a variety of reasons, including too frequent administration, coadministration with other medicines containing paracetamol and prolonged administration of regular paracetamol doses (for a period of up to 24 days).²

Knowledge gaps among parents and carers of young children may contribute to unintentional misuse and overdose of paracetamol. Parents/carers may not be aware of:^3-5

• the risk of liver damage from a single acute overdose or from ongoing administration at supratherapeutic doses
  
• appropriate indications for paracetamol use in children
  
• different strengths and formulations, including why they should avoid adult-strength preparations in children
  
• the fact that accidental exploratory ingestion is associated with most hospitalisations for paracetamol, highlighting the importance of safe storage.
  

Find out more about paracetamol for children

Young children whose mothers have been prescribed opioids are at increased risk of overdose from opioids.⁶ While cases of opioid poisoning are infrequent in the 2018 Bell study,¹ there have been two reports of accidental exposure of children to fentanyl patches in Australia. Both children were hospitalised.⁷

The risk of a partially detached patch being transferred from an adult to an infant is high, as infants are often held by adults.⁸

Toddlers explore their world by touching and tasting things within their reach. They are at increased risk of finding a patch that has been poorly stored or incorrectly disposed of and ingesting it or sticking it onto themselves. Used patches can retain high residual levels of the active ingredient (around 35% to 52% for higher doses and 90% for the 25 microgram-per-hour patch).^8,9

If a fentanyl patch is chewed, a toxic dose may be released,¹⁰ with more than a 30-fold increase in absorption from the buccal mucosa if chewed, compared with the transdermal route.¹¹

All health professionals should remind parents/carers to keep fentanyl patches out of reach of children and to correctly dispose of patches that have been used or are no longer needed. This involves folding the patch so that the adhesive side sticks to itself, before wrapping and carefully disposing of the patch. Unused patches should be returned to a pharmacy for safe disposal. If a fentanyl patch adheres to a child, advise the parent/carer to immediately remove it, and to phone the PIC or go to a hospital, as the child may still experience toxicity after removal.^7,12

Adults who wear patches should consider covering the patch with an adhesive film to keep it on their body and regularly check that the patch is still in place, either by touch or by visual examination.

Parents/carers need to seek medical attention immediately if they suspect that a child may have ingested or been inadvertently exposed to a patch.^7,12

Read more about accidental fentanyl exposure.

In the Bell et al study, for infants (aged < 1 year), 54.9% of cases of exposure reported to the PIC were defined as accidental ingestion, while 44.3% were defined as therapeutic error. In contrast, 87.2% of cases of poisoning for 1–5-year-olds were recorded as accidental ingestion.¹ Developmental stages probably influence this, as infants are less mobile, while children aged 1–3 years are at high risk of accidental poisoning as they explore the world around them.^13,14

Dosing errors are a major source of preventable poisoning. A US study examining how dosing errors could be reduced reported that up to 83.5% of parents make dosing errors, with 29.3% making ≥ 1 large error (ie, more than 2 × dose).¹⁵ Dosing errors are most commonly seen with cup and teaspoon-only labels compared with syringe and millilitre-only labels.^15,16

While most parents currently prefer to see dosing instructions in millilitre (mL) units, some still prefer teaspoon units. However, the similarity of the abbreviations for teaspoons (tsp) and tablespoons (tbsp), can lead to confusion,¹⁷ and result in up to a 4-fold dosing error, considering one teaspoon is 5 mL and one tablespoon in Australia is 20 mL.

Evidence suggests that healthcare providers should encourage parents/carers to use an appropriately marked oral syringe to measure liquid medicines, particularly when small doses are recommended.¹⁶

This is especially significant for drugs with a narrow therapeutic index (NTIDs), such as clonidine, where there is a very small margin between a safe dose and a toxic dose.^16,18

Clonidine is increasingly being used to treat attention deficit hyperactivity disorder and other behavioural disturbances in children.¹⁹ Children who receive a double dose of clonidine often require hospitalisation due to its narrow therapeutic range. Clonidine is the medicine most frequently requiring consultant clinical toxicologist input in this age group.²⁰

Find out how to give medicine to children safely and accurately

1. Use metric dosing for prescribing and dispensing

Historically there have been a number of common errors in dosing, specifically confusion between millilitres and teaspoons. Before dispensing, pharmacists should double-check that the directions on the label match the original prescription.²¹

2. Prescribe, dispense and demonstrate with 5 mL or 10 mL syringes

When demonstrating how to draw up and administer medicine to a child, use 5 mL or 10 mL syringes and match the required dose to the appropriate sized syringe.¹⁵ Ensure the parent/carer understands how to read incremental markings; trial data suggest more errors in administration by carers occur with 2.5 mL and 7.5 mL dose amounts compared with 5 mL dose amounts.¹⁶  

3. Dispense and demonstrate administration with oral, not parenteral, syringes

At times children may be sent home with an IV cannula in place. Oral syringes have specially engineered hubs that cannot be easily or securely connected to standard IV lines, preventing accidental administration through the IV route. In addition, clearly demonstrate to the parent/carer that oral medicines are for oral use only.²²

4. Use a combination of text and pictograms to support low health literacy

Adults with low health literacy may be more likely to find millilitre-dosing difficult. Evidence shows that demonstrating medicine dosage using a combination of text and pictograms results in fewer errors. This includes use of teachback/showback, drawings or pictures of the dose and dose demonstrations and providing dosing tools with millilitre units.¹⁵

5. Ensure parents/carers know that overdose and toxicity can occur with paracetamol

It is important that parents/carers are aware that despite being widely available without a prescription, paracetamol is a medicine and overdose can occur.²³ Some reasons for overdose include dosing every 4 hours over a 24-hour period, resulting in six doses in total; more than one parent/carer administering medicine; and misreading the label.²⁰

Many of the cases of accidental exposure to paracetamol reported to PIC occurred when a bottle was left on the bench or bedside table after dosing, or sometimes left with the cap off.²⁰

When recommending paracetamol for pain relief in children and infants younger than 12 years of age, ensure that parents/carers know the following facts.²³

• Paracetamol comes in different formulations and strengths for different ages – choose the correct paracetamol product for the child's age.
  
• They should keep track of all medicines that are given to the child. This helps prevent accidental overdose through coadministration of medicines that contain the same ingredient, for example paracetamol.¹⁶
  
• There is a potential for liver damage with misuse and overdose of paracetamol, and there are no early signs of hepatotoxicity. Phone the PIC immediately if an overdose is suspected.
  
• It is important to keep a current record of the child's weight. The recommended dose of paracetamol for children is based on ideal body weight (15 mg/kg).
  
• The maximum recommended dosage for children, which is 15 mg/kg every 4–6 hours to a maximum of 1 gram, and no more than 4 doses in a 24-hour period, should never be exceeded.
  

6. Provide intensive support to families whose children are taking NTIDs

Drugs with a narrow therapeutic index (NTIDs) include clonidine, warfarin, carbamazepine, digoxin, phenytoin, tacrolimus and theophylline.¹⁸ For some NTIDs, errors within an even smaller range (< 20% deviation) may be clinically significant and additional intervention strategies are important to reduce errors.¹⁶ With infants, the millilitre dosing of these medicines can be less than 1 mL, so clear education with a 1 mL syringe is essential.

Incidences of exposure and poisoning in children are also strongly correlated with adult medicine prescriptions, with medicines affecting the cardiovascular system (such as statins, angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists) being common causes.¹

Advise parents/carers to store ALL medicines out of reach of children. A locked cupboard at least 1.5 metres off the ground is a good place to store medicines. Also ensure that other family members, such as grandparents, do the same.¹²

Reinforce the safe storage message for ‘one pill can kill’ medicines including verapamil, diltiazem, sulfonylureas, anti-arrhythmics and opioids.^20,24

Calls to PICs have been shown to improve triage, allowing home management of many cases of unintentional exposure, thereby reducing the number of people entering the healthcare system as well as healthcare expenses.¹

However, calls to the NSW PIC declined between 2008 and 2013, while emergency department presentations remained the same. Interestingly, presentations for less urgent poisoning cases increased, indicating that there were people going to hospital who might not have needed to if they had called a PIC.¹

Australian PICs provide nationwide, round-the-clock specialist poisoning advice to healthcare professionals and members of the public. Encourage parents/carers to call the PIC on 13 11 26 if accidental exposure does happen, as their child may not necessarily need to go to hospital. 

Dr Rose Cairns
Senior Poisons Specialist, New South Wales Poisons Information Centre
The Children's Hospital at Westmead