Reported dose as a measure of drug exposure after paracetamol overdose in children.

The decision to administer antidote after paracetamol overdose is based on the extent of drug exposure, and this often relies on the reported dose. Few data exist concerning the validity of this approach in children. The present observational study sought to examine the relationship between the reported dose and paracetamol concentrations in patients aged ≤18 years admitted to York Hospital between October 2008 and November 2010 inclusive. There were 77 cases and casenotes were evaluable in 61, with median age 14 years (IQR 3-15 years), and weight 54.0 kg (18.2-63.5 kg), including 47 females (71%). Paracetamol dose was 83 mg/kg (57-148 mg/kg), and interval between ingestion and serum concentration was 4.5 hours (4.0-5.4 hours). There was a positive correlation between dose and equivalent 4-hour paracetamol concentration: Spearman's rho=0.57, 95% CI 0.36-0.73, P< 0.0001. These findings support the importance of reported dose as part of initial risk assessment, especially in situations where laboratory determination is unhelpful, such as after a staggered ingestion.