HealthDay News — A dosage of 1g intravenous acetaminophen every 6 hours yields serum concentrations below 10µg/mL for critically ill multiple-trauma patients, according to a study published online April 17 in the Journal of Clinical Pharmacology.

Oscar Fuster-Lluch, PhD, from the Hospital Universitari i Politècnic La Fe in Valencia, Spain, and colleagues examined the pharmacokinetic profile of intravenous acetaminophen administered to critically ill multiple-trauma patients after 4 doses of 1g every 6 hours. Serum and urine acetaminophen concentrations were assessed and used to calculate pharmacokinetic parameters. Data were included for 22 patients (age, 44 years), mostly males (68%), who were not obese. 

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The researchers found that the maximum acetaminophen concentration was 33.6 µg/mL and the minimum concentration was 0.5µg/mL. All values were below 10µg/mL and 8 were below the limit of detection. Serum and renal clearance were 28.8 L/hour and 15 mL/min, respectively. For a steady-state minimum concentration of 10 µg/mL, the theoretical daily dose would be 12.2g/day; the dose would be 6.9g/day for an average steady-state concentration of 10µg/mL.

“In conclusion, administration of acetaminophen at the recommended dosage of 1g per six hours to critically ill multiple-trauma patients yields serum concentrations below 10µg/mL due to increased elimination,” the authors write. “To reach the 10µg/mL target, and from a strictly pharmacokinetic point of view, continuous infusion may be more feasible than bolus dosing.”

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