Uptake Mechanism of Pitavastatin, a New Inhibitor of HMG-CoA Reductase, in Rat Hepatocytes

Shimada, Shunsuke; Fujino, Hideki; Morikawa, Takashi; Moriyasu, Matsuko; Kojima, Junji

doi:10.2133/dmpk.18.245

Cited by 32 publications

(23 citation statements)

References 32 publications

(35 reference statements)

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“…For CCK8 and deltorphin II in CHO cells the extremely low observed P dif values were, respectively, 0. , 1992;Ismair et al, 2001;Shimada et al, 2003;Lancon et al, 2004;Treiber et al, 2004;Ho et al, 2006). For many transporter model substrates, such as taurocholate and estrone-3-sulfate, which have negligible passive diffusion, this approach is appropriate.…”

Section: Discussionmentioning

confidence: 99%

“…In hepatocytes, passive processes are typically assessed in a parallel incubation at 4°C to disable any active transport proteins (Komai et al, 1992;Ismair et al, 2001;Shimada et al, 2003;Lancon et al, 2004;Treiber et al, 2004;Ho et al, 2006). However, whereas active transport is inhibited at low temperature, passive processes might also be altered as membrane fluidity decreases (Frezard and GarnierSuillerot, 1998;Neuhoff et al, 2005;Webborn et al, 2007).…”

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confidence: 99%

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Design, Data Analysis, and Simulation of in Vitro Drug Transport Kinetic Experiments Using a Mechanistic in Vitro Model

Poirier

Lavé²,

Portmann³

et al. 2008

Drug Metab Dispos

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ABSTRACT:The use of in vitro data for quantitative predictions of transportermediated elimination in vivo requires an accurate estimation of the transporter Michaelis-Menten parameters, V max and K m , as a first step. Therefore, the experimental conditions of in vitro studies used to assess hepatic uptake transport were optimized regarding active transport processes, nonspecific binding, and passive diffusion (P dif ). A mechanistic model was developed to analyze and accurately describe these active and passive processes. This twocompartmental model was parameterized to account for nonspecific binding, bidirectional passive diffusion, and active uptake processes based on the physiology of the cells. The model was used to estimate kinetic parameters of in vitro transport data from organic anion-transporting peptide model substrates (e.g., cholecystokinin octapeptide deltorphin II, fexofenadine, and pitavastatin). Data analysis by this mechanistic model significantly improved the accuracy and precision in all derived parameters [mean coefficient of variations (CVs) for V max and K m were 19 and 23%, respectively] compared with the conventional kinetic method of transport data analysis (mean CVs were 58 and 115%, respectively, using this method). Furthermore, permeability was found to be highly temperature-dependent in Chinese hamster ovary (CHO) control cells and artificial membranes (parallel artificial membrane permeability assay). Whereas for some compounds (taurocholate, estrone-3-sulfate, and propranolol) the effect was moderate (1.5-6-fold higher permeability at 37°C compared with that at 4°C), for fexofenadine a 16-fold higher passive permeability was seen at 37°C. Therefore, P dif was better predicted if it was evaluated under the same experimental conditions as V max and K m , i.e., in a single incubation of CHO overexpressed cells or rat hepatocytes at 37°C, instead of a parallel control evaluation at 4°C.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Design, Data Analysis, and Simulation of in Vitro Drug Transport Kinetic Experiments Using a Mechanistic in Vitro Model

Poirier

Lavé²,

Portmann³

et al. 2008

Drug Metab Dispos

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“…In the present study, drug associated with the hepatocytes was measured after separation from free drug by layering the suspension of drug and hepatocytes over silicone/mineral oil followed by rapid centrifugation Ϫ the oil-spin method (Petzinger and Fuckel, 1992), a method used by several groups (Ishigami et al, 1995;Nakai et al, 2001;Nezasa et al, 2003;Shimada et al, 2003;Hallifax and Houston, 2006) to characterize hepatic uptake by a clearance term for active transport, CL active , together with K m and V max and a passive permeability parameter, P diff . As enzyme-transporter interplay complicates the interpretation of many of these types of studies, the nonspecific P450 inhibitor, l-aminobenzotriazole (ABT) (Mico et al, 1988), has been used to eliminate any potential metabolism.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Characterization of Rat Hepatic Uptake of 16 Actively Transported Drugs

Galetin²,

2011

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ABSTRACT:To explore the determinants of hepatic uptake, 16 compounds were investigated with different physicochemical and disposition characteristics, including five statins, three sartans, saquinavir, ritonavir, erythromycin, clarithromycin, nateglinide, repaglinide, fexofenadine, and bosentan. Freshly isolated rat hepatocytes in suspension were used with the oil-spin method to generate kinetic parameters. Clearances, via passive diffusion (P diff ) and active uptake (CL active , characterized by maximal uptake rate and K m ), were estimated from the initial uptake rate data over a 0.01 to 100 M concentration range. The K m values had a range of 15-fold, with 10 of the 16 drugs with K m < 10 M (median 6 M). Both CL active and P diff ranged over 100-fold (median 188 and 14 l/min/ 10 6 cells). Assessment of the relative contribution of P diff and CL active indicated that, at low concentrations (approximately 0.1 M), the active process contributes >80% to the overall uptake for 13 drugs. Although high P diff values were obtained for ritonavir and repaglinide, active process contributed predominantly to uptake; in contrast, high passive permeability dominates over transportermediated uptake for saquinavir over the full concentration range. For bosentan and erythromycin, active and passive processes were equally important. Hepatocyte-to-medium unbound concentration ratio was >10 for 9 of the 16 drugs, ranging from 2 to 494 for bosentan and atorvastatin, respectively. Some drugs showed extensive intracellular binding (fraction unbound range 0.01-0.6), which was not correlated with active uptake. LogD 7.4 correlated significantly with P diff and the extent of intracellular binding but not with active uptake. This study provides systematic assessment of the role of active uptake relative to the passive process; implications of the findings are discussed.

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“…Shimada et al (2003) have recently reported that the uptake of pitavastatin by rat hepatocytes is saturable and temperature dependent, suggesting that pitavastatin might be transported by carrier-mediated systems. Pitavastatin is scarcely metabolized in human liver microsomes and is excreted into the bile in unchanged form (Kojima et al, 2001).…”

mentioning

confidence: 99%

Contribution of OATP2 (OATP1B1) and OATP8 (OATP1B3) to the Hepatic Uptake of Pitavastatin in Humans

Hirano

Maeda²,

Shitara³

et al. 2004

J Pharmacol Exp Ther

420

396

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Pitavastatin, a novel potent 3-hydroxymethylglutaryl-CoA reductase inhibitor, is selectively distributed to the liver in rats. However, the hepatic uptake mechanism of pitavastatin has not been clarified yet. In the present study, we investigated the contribution of organic anion transporting polypeptide 2 (OATP2/OATP1B1) and OATP8 (OATP1B3) to pitavastatin uptake using transporter-expressing HEK293 cells and human cryopreserved hepatocytes. Uptake studies using OATP2-and OATP8-expressing cells revealed a saturable and Na ϩ -independent uptake, with K m values of 3.0 and 3.3 M for OATP2 and OATP8, respectively. To determine which transporter is more important for its hepatic uptake, we proposed a methodology for estimating their quantitative contribution to the overall hepatic uptake by comparing the uptake clearance of pitavastatin with that of reference compounds (a selective substrate for OATP2 (estrone-3-sulfate) and OATP8 (cholecystokinin octapeptide) in expression systems and human hepatocytes. The concept of this method is similar to the so-called relative activity factor method often used in estimating the contribution of each cytochrome P450 isoform to the overall metabolism. Applying this method to pitavastatin, the observed uptake clearance in human hepatocytes could be almost completely accounted for by OATP2 and OATP8, and about 90% of the total hepatic clearance could be accounted for by OATP2. This result was also supported by estimating the relative expression level of each transporter in expression systems and hepatocytes by Western blot analysis. These results suggest that OATP2 is the most important transporter for the hepatic uptake of pitavastatin in humans.

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Uptake Mechanism of Pitavastatin, a New Inhibitor of HMG-CoA Reductase, in Rat Hepatocytes

Cited by 32 publications

References 32 publications

Design, Data Analysis, and Simulation of in Vitro Drug Transport Kinetic Experiments Using a Mechanistic in Vitro Model

Design, Data Analysis, and Simulation of in Vitro Drug Transport Kinetic Experiments Using a Mechanistic in Vitro Model

Kinetic Characterization of Rat Hepatic Uptake of 16 Actively Transported Drugs

Contribution of OATP2 (OATP1B1) and OATP8 (OATP1B3) to the Hepatic Uptake of Pitavastatin in Humans

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