In vivo electrochemical recording of acetaminophen in non human primate brain

In vivo electrochemical recordings were obtained from the caudate nucleus of three young adult pigtail monkeys (M. nemestrina) following the oral administration of acetaminophen (APAP) (75 mg/kg). Using linear sweep voltammetry, electrodes in the right and left caudate were scanned alternately every five minutes. The electrochemical peak resulting from the APAP was monitored for at least 140 minutes following drug administration. Maximum APAP levels were detected in the monkey caudate 40 minutes following drug administration. Both right and left caudate displayed an identical time course, with oxidation potentials (Eox) similar on both sides of the brain. Blood samples were collected from one monkey by means of an intravenous catheter. Samples were obtained at approximately 5-minute intervals and over a period of 140 minutes following oral administration of APAP. Concentration of APAP in serum peaked 25 minutes after administration. In this animal the maximum electrochemical peak height was detected 40 minutes following APAP administration. These findings demonstrate the ability to measure APAP in the caudate nucleus of awake monkeys by means of electrochemical detection. This method may be useful for calibrating electrochemical electrodes in vivo, and it also provides a model system for studying drug kinetics in the brain.