Tissue distribution of 35S-metabolically labeled neublastin (BG00010) in rats

Utility of quantitative whole-body autoradiography (QWBA) and oxidative combustion (OC) analysis in the assessment of tissue distribution of [14C]Mefuparib (CVL218) in SD and LE rats

BACKGROUND

In tissue distribution studies of radiopharmaceuticals, quantitative whole-body autoradiography (QWBA) and oxidative combustion (OC) analysis are the two important methods that have not been compared using the same drug. Sprague-Dawley (SD) and Long-Evans (LE) rats, both of which are commonly used rodents in tissue distribution studies, have also not been compared using the same drug. Comparative studies are important for aiding the selection of appropriate experimental methods and animals.

METHODS

To evaluate the tissue distribution of [14C]Mefuparib (CVL218) in rats and assess its clinical safety, QWBA and OC analysis were used. The differences between the two methods were noted. Comparisons between the tissue distribution results of LE and SD rats were also done.

RESULTS

The QWBA and OC distribution analysis showed that [14C]CVL218-related radioactivity could be distributed in 19 tissues. For 89.47% of the tissues, no significant differences were noted between the two methods. There were also no differences in the pharmacokinetics data for plasma and brain homogenates between LE and SD rats. However, the pharmacokinetics data for liver and kidney homogenates were seven-fold higher in LE rats than in SD ones.

CONCLUSIONS

Both the OC and QWBA methods revealed that [14C]CVL218 could be widely distributed in the tissues of rats. The OC had a lower limit of quantification while QWBA provided a more comprehensive analysis of [14C]CVL218 distribution. More safety was associated with using LE rat data to estimate the dosimetry of [14C]CVL218 for the whole-body, for human radiolabeled mass balance studies.

Imaging Technologies for Cerebral Pharmacokinetic Studies: Progress and Perspectives

Pharmacokinetic assessment of drug disposition processes in vivo is critical in predicting pharmacodynamics and toxicology to reduce the risk of inappropriate drug development. The blood–brain barrier (BBB), a special physiological structure in brain tissue, hinders the entry of targeted drugs into the central nervous system (CNS), making the drug concentrations in target tissue correlate poorly with the blood drug concentrations. Additionally, once non-CNS drugs act directly on the fragile and important brain tissue, they may produce extra-therapeutic effects that may impair CNS function. Thus, an intracerebral pharmacokinetic study was developed to reflect the disposition and course of action of drugs following intracerebral absorption. Through an increasing understanding of the fine structure in the brain and the rapid development of analytical techniques, cerebral pharmacokinetic techniques have developed into non-invasive imaging techniques. Through non-invasive imaging techniques, molecules can be tracked and visualized in the entire BBB, visualizing how they enter the BBB, allowing quantitative tools to be combined with the imaging system to derive reliable pharmacokinetic profiles. The advent of imaging-based pharmacokinetic techniques in the brain has made the field of intracerebral pharmacokinetics more complete and reliable, paving the way for elucidating the dynamics of drug action in the brain and predicting its course. The paper reviews the development and application of imaging technologies for cerebral pharmacokinetic study, represented by optical imaging, radiographic autoradiography, radionuclide imaging and mass spectrometry imaging, and objectively evaluates the advantages and limitations of these methods for predicting the pharmacodynamic and toxic effects of drugs in brain tissues.