PHARMACOKINETICS OF EXTENDED RELIEF VS REGULAR RELEASE TYLENOL IN SIMULATED HUMAN OVERDOSE

Background: The purpose of this trial was to compare the pharmacokinet ics 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 formula tion 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(R). Results: The area under the curves for extended relief acetaminophen and regular release acetaminophen were 426 mg h/L and 4 32 mg/L, respectively (p = 0.768). The mean half times for extended re lief 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 acetaminophe n, respectively (p < 0.001) and the mean time to maximum serum acetami nophen concentrations were 0.87 h and 0.75 h for extended relief aceta minophen and regular release acetaminophen, respectively (p = 0.508). Conclusions: Although the formulations appear to have equal bioavailab ility, their half-lives and peak concentrations were significantly dif ferent. Further study is required to determine whether these differenc es affect the assessment and management of poisoned patients.