USING OFLOXACIN AS A TIME MARKER IN HAIR ANALYSIS FOR MONITORING THE DOSAGE HISTORY OF HALOPERIDOL

Hair samples were obtained 1-5 months after ingestion of the antimicro bial ofloxacin, which had been given for 1 or 3 days at the commenceme nt of haloperidol administration, or when its dosage was reduced. The axial distribution of ofloxacin, haloperidol and its active metabolite , reduced haloperidol, was analysed in segments from single strands of hair. Ofloxacin was detected where the content of haloperidol and red uced haloperidol along the hair shaft showed a sharp change, correspon ding to the change in dose. When we matched the time scale of the dosa ge history to the growth rate, which was estimated using ofloxacin as the time marker, the distribution of the haloperidol and reduced halop eridol precisely coincided with the rise and fall in the dose of halop eridol. These findings demonstrate that ofloxacin can serve as a time marker when drug distribution along the hair shaft is used to obtain t he drug exposure history of an individual.