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Pharmacokinetics of intraventricular administration
Journal of Neuro-Oncology
|January 1, 1983
Summary
Drug removal from cerebrospinal fluid (CSF) is limited by physiological factors, resulting in consistent drug half-times in CSF. This finding impacts drug delivery and pharmacokinetic studies.
Area of Science:
- Neuroscience
- Pharmacology
- Biomedical Engineering
Background:
- Neurosurgical devices enable intraventricular drug delivery, increasing the need for cerebrospinal fluid (CSF) pharmacokinetic studies.
- Observed CSF concentration-time data for various drugs show a narrow range when normalized for dose.
Purpose of the Study:
- To investigate the physiological limitations governing drug removal from CSF.
- To develop a predictive model for CSF drug concentrations following intraventricular administration.
Main Methods:
- Utilized a distributed model of the central nervous system to simulate drug pharmacokinetics.
- Analyzed CSF concentration-time data normalized for dose.
- Estimated drug removal rates based on bulk flow and capillary exchange.
Main Results:
- Physiological limits on drug removal create a narrow range of CSF half-times after bolus administration.
- The maximum rate of drug egress is limited to seven times the minimum rate set by bulk CSF flow.
- CSF capillary exchange rates can predict drug concentration-time profiles.
Conclusions:
- Drug elimination from CSF is primarily constrained by physiological removal mechanisms, not drug properties.
- The developed model can predict CSF drug concentrations for both bolus and continuous infusion delivery.