5. Limitation
In this study, we have evaluated CSF-to-serum ratio of TGC at
steady-state trough concentration based on bio-samples from 12 patients
with CNSI. For lots of drugs, previous studies has demonstrated that the
peak time and clearance time in brain were longer than that in plasma[19, 20]. This might lead to the difference of
CSF-to-serum ratio at different periods [8].
Therefore, the evaluation of penetration ability of TGC through BBB
based on CSF-to-serum ratio at single period might be influenced by
above factors. Increasing of the sample collection points would made the
study more potent. And in our study, we compared our results with the
data of 6 healthy adults reported by Rodvold [8].
We should not ignore the possible influence of different dosage scheme
and sample time occurred in these two studies. However, collection of
CSF samples was quite invasive, which makes CSF samples from health
human and multipoint collection could not be achieved.