抄録
It has been recognized that the pharmacologic effect and the adverse reaction of a drug are closely related to the concentration of its free form at the site of action. The measurement of this concentration is very important to manage the optimal therapeutic response with the minimum adverse effects but it is practically impossible. The cerebrospinal fluid (CSF) concentration of a drug which acts on the central nervous systems is believe to be instantaneously equilibrated with its concentration at the site of action. The tear concentration of a drug reflects not only its plasma free concentration but also its CSF concentration. The individualization of the dosage regimen become to be very important for the drugs with narrow therapeutic windows such as anticonvulsants and antiasthmatics. The purpose of the present study is to develop a pharmacokinetic model for theophylline and valproic acid in tear and CSF, and to examine whether their CSF concentrations can be predicted by their tear concentrations in patients. The time courses of theophylline and valproic acid concentrations in guinea pig CSF and tear were similar to those of their free concentrations in plasma, and could be described by a basic physiological model in which their CSF and tear compartments are independently connected with their plasma compartments (free drugs) based on the apparent diffusion constants. The CSF concentrations of theophylline at the steady states of both guinea pigs and patients could be predicted by its tear concentrations using the resulting pharmacokinetic parameters. The measurement of the drug concentrations in tear which can be collected non-invasively might be a very useful method for individual dosage regiment of these drugs in patients.
