Novel in vitro dynamic metabolic system for predicting the human pharmacokinetics of tolbutamide.

Liver metabolism is commonly considered the major determinant in drug discovery and development. Many in vitro drug metabolic studies have been developed and applied to understand biotransformation. However, these methods have disadvantages, resulting in inconsistencies between in vivo and in vitro experiments. A major factor is that they are static systems that do not consider the transport process in the liver. Here we developed an in vitro dynamic metabolic system (Bio-PK metabolic system) to mimic the human pharmacokinetics of tolbutamide. Human liver microsomes (HLMs) encapsulated in a F127'-Acr-Bis hydrogel (FAB hydrogel) were placed in the incubation system. A microdialysis sampling technique was used to monitor the metabolic behavior of tolbutamide in hydrogels. The measured results in the system were used to fit the in vitro intrinsic clearance of tolbutamide with a mathematical model. Then, a PBPK model that integrated the corresponding in vitro intrinsic clearance was developed to verify the system. Compared to the traditional incubation method, reasonable PK profiles and the in vivo clearance of tolbutamide could be predicted by integrating the intrinsic clearance of tolbutamide obtained from the Bio-PK metabolic system into the PBPK model. The predicted maximum concentration (Cmax), area under the concentration-time curve (AUC), time to reach the maximum plasma concentration (Tmax) and in vivo clearance were consistent with the clinically observed data. This novel in vitro dynamic metabolic system can compensate for some limitations of traditional incubation methods; it may provide a new method for screening compounds and predicting pharmacokinetics in the early stages, supporting the development of compounds.

[The preparation of oligonucleotide chips for detecting BMPR-IB gene polymorphism in sheep].

BMPR-IB gene increases ovulation rate and litter size as a major gene in Chinese Merino, because of 746 A to G mutation. The aim of this study was to make oligonucleotide chips to determine single nucleotide polymorphism (SNP) in BMPR-IB gene. The oligonucleotide chips were manufactured by using six sequence-specific oligonucleotide probes derived from polymorphic regions in the mutation and spotting the probes by microarrayer onto the aldehyde modified glass slides. The 746 A to G mutation was detected with ovine blood in reaction cells of chips. The results were identified by designed the Arraydoctor 2.0 software, in accordance with those of restriction fragment length polymorphisms (RFLP). The results showed the oligonucleotide chips are a parallel, accurate and effective way for screening prolificacy in molecular-assisted selection(MAS)of sheep.