PHARMACOKINETICS OF ACETAMINOPHEN IN THE CEREBROSPINAL-FLUID IN ELDERLY POPULATION

We investigated acetaminophen pharmacokinetics in CSF in twelve operat ed arteritics patients with continuous spinal anesthesia. Nine men and three women aged 77 +/- 7 years and weighing 66 +/- 15 kg entered in the study after expressing verbal informed consent. They received intr avenously a single dose of acetominophen (equivalent to 1 g). Fifteen minutes to six hours after the intravenous injection, blood and CSF sa mples were withdrawn every thirty minutes, except during the second to the third hour were it was every fifteen minutes. Acetaminophen conce ntrations in blood and in CSF were assayed by HPLC. Acetaminophen was detected in the earliest samples (1,32 +/- 1,32 mug.ml-1) and then inc reased up to 8,16 +/- 3,04 mug.ml-1 at 186 +/- 56 minutes. From 135th to 345th minute, acetaminophen concentration in CSF stay at about 6 mu g.ml-1, which is the duration of its maximal analgesic central effect.