Acetaminophen dosing guidelines needed for overweight children, study shows

There is considerable discrepancy among caregivers and pharmacists regarding the appropriate dosage of acetaminophen for overweight and obese children, according to a recent study published online August 20 in the European Journal of Hospital Pharmacy Science and Practice.

In a study conducted by Michael David Wiese, PhD, of the Sansom Institute for Health Research, Division of Health Sciences at the University of South Australia, and colleagues, caregivers and pharmacists from a single pediatric emergency room were presented with three hypothetical scenarios and asked to state the dose of medication they would recommend (for pharmacists) or administer (for caregivers) in each situation.

The investigators found that 68% of pharmacists would recommend and 49% of caregivers would administer a dose of acetaminophen based on weight - rather than the recommended and potentially too-low dose based on age - when presented with an 8-year-old patient weighing 32 kg (71 lbs.), which is 7 kg (15 lbs.) more than the average weight for a patient that age.

When presented with an 8-year-old child weighing 50 kg (110 lbs.), for which there are no weight-based recommendations, pharmacists recommended a dose ranging from 8 to 16 mL, with 64% of pharmacists saying they’d recommend a dose ranging from 13 to 16 mL. Less than half (49%) of caregivers stated that this was the dose that they would administer, whereas 26% did not provide a recommendation.

When the responses were adjusted for actual body weight, most recommended doses were between 10 and 20 mg/kg. However, when the dose was corrected for ideal body weight (IBW), the further the child was above their IBW, the higher the dose that was recommended-amounting to doses above 20 mg/kg IBW.

“It is unclear if this dosage strategy is appropriate in these children,” the authors wrote, “but if a dosage reduction is appropriate for overweight and obese children as has been recommended in some guidelines, then these children may be at increased risk of toxicity.”

The authors say the data highlight the need to develop simple, evidence-based guidelines for dosing in overweight and obese children and future research should focus on determining the impact of dosing practices in these children and the appropriate metric necessary for calculating doses.