Pharmacokinetics of Extended Relief vs Regular Release Tylenol in Simulated Human Overdose

Abstract

Background: The purpose of this trial was to compare the pharmacokinetics of the two available acetaminophen dosage forms in simulated human overdose. Methods: Ten healthy volunteers received acetaminophen, 75 mg/kg orally, either as the regular release or extended relief formulation in a random, crossover fashion. Blood samples were analyzed using a TDx assay and a best fit correlation of data points was determined by PCNONLIN*. Results: The area under the curves for extended relief acetaminophen and regular release acetaminophen were 426 mg h/L and 432 mg h/L, respectively (p = 0.768). The mean half times for extended relief acetaminophen and regular release acetaminophen were 4.02 h and 2.56 h, respectively (p <0.001). The mean maximum serum acetaminophen concentrations were 62.6 mg/L (414.4 mmol/L) and 94.3 mg/L (624.3 mmol/L) for extended relief acetaminophen and regular release acetaminophen, respectively (p <0.001) and the mean time to maximum serum acetaminophen concentrations were 0.87 h and 0.75 hfor extended relief acetaminophen and regular release acetaminophen, respectively (p = 0.508). Conclusions: Although the formulations appear to have equal bioavailability, their half-lives and peak concentrations were significantly different. Further study is required to determine whether these differences affect the assessment and management of poisoned patients.