Biopharmaceutical profiling of a pyrido[4,3-d] pyrimidine compound library

Evaluation of oral pharmacokinetics, in vitro metabolism, blood partitioning and plasma protein binding of novel antidiabetic agent, S009-0629 in rats

S009-0629 [methyl-8-(methylthio)-2-phenyl-6-p-tolyl-4,5-dihydro-2H-benzo[e]indazole-9-carboxylate] is a novel antidiabetic agent with PTP1B inhibitory activity. In this study, we have investigated the in vitro metabolic stability, plasma protein binding, blood partitioning, and oral pharmacokinetic study of S009-0629 in rats. The plasma protein binding, blood partitioning, and metabolic stability were determined by HPLC method. The oral pharmacokinetic study was analyzed by liquid chromatography coupled mass spectrometry (LC-MS/MS) method. The plasma protein binding of S009-0629 using modified charcoal adsorption method at 5 and 10 µg/mL was 80.58 ± 1.04% and 81.95 ± 1.15%, respectively. The K_RBC/PL of S009-0629 was independent of concentration and time. The in-vitro half-life of S009-0629 at 5 and 10 µM using rat liver microsomes was determined as 273 ± 24.46 and 281.67 ± 26.53 min, respectively. After oral administration, S009-0629 exhibited C_max 55.51 ± 1.18 ng/mL was observed at 18 hr (t_max ). S009-0629 was found to have the large apparent volume of distribution (1,894.93 ± 363.67 L/kg). Oral in-vivo t_1/2 of S009-0629 was found to be 41.23 ± 5.96 hr. A rapid and highly sensitive LC-MS/MS method was validated for S009-0629 in rat plasma. S009-0629 has high plasma protein binding and low hepatic extraction. S009-0629 has no affinity with human P-gp and BCRP in ATPase assay. After oral dosing, S009-0629 has slow absorption and elimination in rats.

Effect of Cryopreservation on Enzyme and Transporter Activities in Suspended and Sandwich Cultured Rat Hepatocytes

Freshly-isolated rat hepatocytes are commonly used as tools for hepatic drug disposition. From an ethical point of view, it is important to maximize the use of isolated hepatocytes by cryopreservation. The present study compared overall hepatocyte functionality as well as activity of the organic anion transporting polypeptide (Oatp), multidrug resistance-associated protein 2 (Mrp2), and UDP-glucuronosyltransferase 1 (Ugt1), in in vitro models established with cryopreserved and freshly-isolated hepatocytes. A similar culture time-dependent decline in cellular functionality, as assessed by urea production, was observed in sandwich-cultured hepatocytes (SCH) obtained from freshly-isolated and cryopreserved cells. Concentration-dependent uptake kinetics of the Oatp substrate sodium fluorescein in suspended hepatocytes (SH) or SCH were not significantly affected by cryopreservation. Mrp2-mediated biliary excretion of 5 (and 6)-carboxy-2',7'-dichlorofluorescein by SCH was assessed with semi-quantitative fluorescence imaging: biliary excretion index values increased between day 3 and day 4, but did not differ significantly between cryopreserved and freshly-isolated hepatocytes. Finally, telmisartan disposition was evaluated in SCH to simultaneously explore Oatp, Ugt1, and Mrp2 activity. In order to distinguish between the susceptibilities of the individual disposition pathways to cryopreservation, a mechanistic cellular disposition model was developed. Basolateral and canalicular efflux as well as glucuronidation of telmisartan were affected by cryopreservation. In contrast, the disposition parameters of telmisartan-glucuronide were not impacted by cryopreservation. Overall, the relative contribution of the rate-determining processes (uptake, metabolism, efflux) remained unaltered between cryopreserved and freshly-isolated hepatocytes, indicating that cryopreserved hepatocytes are a suitable alternative for freshly-isolated hepatocytes when studying these cellular disposition pathways.

Recent developments in the chemistry of bicyclic 6-6 systems: chemistry of pyrido[4,3-d]pyrimidines

The present review reports the chemistry and biological importance of pyrido[4,3-d]pyrimidine analogues.

Straightforward entry to pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones and their ADME properties

A straightforward synthesis of pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones was developed starting from 2-chloropyridine-3-carboxylic acid by esterification, nucleophilic aromatic substitution and amide formation in one step, and ring closure allowing their synthesis with two identical or two different group attached to nitrogen. The structural diversity of these [2,3-d]pyrimidine-2,4(1H,3H)-diones resulted in significant variation in the biopharmaceutical properties. This was reflected by the broad range in fasted state simulated intestinal fluid solubility values (12.6 μM to 13.8 mM), Caco-2 permeability coefficients (1.2 × 10(-6)cm/s to 90.7 × 10(-6)cm/s) and in vitro-predicted human in vivo intrinsic clearance values (0 to 159 ml/min/kg).

Synthesis and antiproliferative evaluation of novel tetrahydrobenzo[4′,5′]thieno[3′,2′:5,6]pyrido[4,3-d]pyrimidine derivatives

A series of tetrahydrobenzo[4′,5′]thienophene[3′,2′:5,6]pyrido[4,3-d]pyrimidine-4-(3H)-one derivatives were synthesized and evaluated for their antiproliferative activities.