The Novel In Vitro Method to Calculate Tissue-to-Plasma Partition Coefficient in Humans for Predicting Pharmacokinetic Profiles by Physiologically-Based Pharmacokinetic Model With High Predictability.

Proper prediction of human pharmacokinetic (PK) profiles can accelerate the compound selection in drug discovery. Recently, we reported a robust bottom-up physiologically-based pharmacokinetic (PBPK) approach (J Pharm Sci. 2019 Aug; 108(8):2718-2727), which uses the in vivo rat distribution volume at the steady state (V) to determine human tissue-to-plasma partition coefficients (Kp).

Successful Prediction of Human Pharmacokinetics After Oral Administration by Optimized Physiologically Based Pharmacokinetics Approach and Permeation Assay Using Human Induced Pluripotent Stem Cell-Derived Intestinal Epithelial Cells.

None of the physiologically based pharmacokinetic (PBPK) approaches using preclinical data show high predictability of human pharmacokinetic (PK) profiles for drugs affected by the intestinal first-pass effect. Here we report a novel PBPK approach that incorporated the findings of a permeation study using human induced pluripotent stem cell-derived intestinal epithelial cells (hiPSC-IECs) to predict human PK profiles after oral administration of drugs. In hiPSC-IECs, gene expression levels of cytochrome P450 3A4 (CYP3A4) and P-glycoprotein (P-gp) are enhanced by rifampicin and 1,25-dihydroxyvitamin D.

Successful Prediction of Human Pharmacokinetics by Improving Calculation Processes of Physiologically Based Pharmacokinetic Approach.

The physiologically based pharmacokinetics (PBPK) model is a major mechanistic approach for predicting human pharmacokinetics (PK) using drug-specific and physiological parameters but has been difficult to use for human PK prediction with acceptable accuracy. Here, we report a newly developed PBPK approach that incorporates the mechanism of albumin-mediated membrane penetration in the liver and interspecies correlation for unbound tissue fractions. To verify the utility of our PBPK approach, we used 12 drugs that are mainly eliminated by hepatic metabolism to compare the prediction accuracy with a conventional PBPK approach and to observe human PK parameters.

Minimal contribution of P-gp on the low brain distribution of naldemedine, a peripherally acting μ-opioid receptor antagonist.

Naldemedine tosylate, a peripherally acting μ-opioid receptor antagonist, is indicated for treatment of opioid induced constipation in both Japan and US. Naldemedine has limited ability to affect the central analgesic effect of opioid analgesics. In this study, we investigated the contribution of P-glycoprotein (P-gp) on the brain distribution of naldemedine.

Pharmacokinetic-Pharmacodynamic Modeling of Brain Dopamine Levels Based on Dopamine Transporter Occupancy after Administration of Methylphenidate in Rats.

Dopamine exerts various effects including movement coordination and reward. It is useful to understand the quantitative relationship between drug pharmacokinetics and target engagement such as the change in occupancy and dopamine level in brain for the proper treatment of dopamine-related diseases. This study was aimed at developing a pharmacokinetic-pharmacodynamic (PK-PD) model based on dopamine transporter (DAT) occupancies that could describe changes in extracellular dopamine levels in brain after administration of methylphenidate (a DAT inhibitor) to rat.

Absorption, distribution, metabolism, and excretion of radiolabeled naldemedine in healthy subjects.

1. Naldemedine is a peripherally acting μ-opioid receptor antagonist for the treatment of opioid-induced constipation. 2.

Application of Intestinal Epithelial Cells Differentiated from Human Induced Pluripotent Stem Cells for Studies of Prodrug Hydrolysis and Drug Absorption in the Small Intestine.

Cell models to investigate intestinal absorption functions, such as those of transporters and metabolic enzymes, are essential for oral drug discovery and development. The purpose of this study was to generate intestinal epithelial cells from human induced pluripotent stem cells (hiPSC-IECs) and then clarify whether the functions of hydrolase and transporters in them reflect oral drug absorption in the small intestine. The hiPSC-IECs showed the transport activities of P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and peptide transporter 1 (PEPT1), revealed by using their probe substrates ([H]digoxin, sulfasalazine, and [C]glycylsarcosine), and the metabolic activities of CYP3A4, CES2, and CES1, which were clarified using their probe substrates (midazolam, irinotecan, and temocapril).

Discovery of Potent and Centrally Active 6-Substituted 5-Fluoro-1,3-dihydro-oxazine β-Secretase (BACE1) Inhibitors via Active Conformation Stabilization.

β-Secretase (BACE1) has an essential role in the production of amyloid β peptides that accumulate in patients with Alzheimer's disease (AD). Thus, inhibition of BACE1 is considered to be a disease-modifying approach for the treatment of AD. Our hit-to-lead efforts led to a cellular potent 1,3-dihydro-oxazine 6, which however inhibited hERG and showed high P-gp efflux.

Rational Design of Novel 1,3-Oxazine Based β-Secretase (BACE1) Inhibitors: Incorporation of a Double Bond To Reduce P-gp Efflux Leading to Robust Aβ Reduction in the Brain.

Accumulation of Aβ peptides is a hallmark of Alzheimer's disease (AD) and is considered a causal factor in the pathogenesis of AD. β-Secretase (BACE1) is a key enzyme responsible for producing Aβ peptides, and thus agents that inhibit BACE1 should be beneficial for disease-modifying treatment of AD. Here we describe the discovery and optimization of novel oxazine-based BACE1 inhibitors by lowering amidine basicity with the incorporation of a double bond to improve brain penetration.

Improved Human Pharmacokinetic Prediction of Hepatically Metabolized Drugs With Species-Specific Systemic Clearance.

Accurate prediction of human pharmacokinetics (PK) is important for the choice of promising compounds in humans. As the predictability of human PK by an empirical approach is low for drugs with species-specific PK, the utility of a physiologically based pharmacokinetic (PBPK) model was verified using 16 hepatically metabolized reference drugs. After the prediction method for total clearance (CL) and distribution volume at steady state (Vd) in the conventional PBPK model had been optimized, plasma concentrations following a single oral administration of each reference drug to healthy volunteers were simulated, and the prediction accuracy for human PK was compared between empirical approaches and the optimized PBPK model.

Cysteine scanning mutagenesis of transmembrane domain 10 in organic anion transporting polypeptide 1B1.

Organic anion transporting polypeptide (OATP) 1B1 is an important drug transporter expressed in human hepatocytes. Previous studies have indicated that transmembrane (TM) domain 2, 6, 8, 9, and in particular 10 might be part of the substrate binding site/translocation pathway. To explore which amino acids in TM10 are important for substrate transport, we mutated 34 amino acids individually to cysteines, expressed them in HEK293 cells, and determined their surface expression.

Role of Na+/L-carnitine transporter (OCTN2) in renal handling of pivaloylcarnitine and valproylcarnitine formed during pivalic acid-containing prodrugs and valproic acid treatment.

Pivalic acid and valproic acid decreases L-carnitine concentration in the body via urinary excretion of their acylcarnitines, pivaloylcarnitine (PC) and valproylcarnitine (VC). To obtain an information about the mechanism of the physiological response, we investigated the renal handling of these acylcarnitines by Na+/L-carnitine cotransporter, OCTN2 using the isolated perfused rat kidney, rat OCTN2 (rOCTN2) and human OCTN2 (hOCTN2) expressing cells. In the perfused rat kidney, PC and VC were strongly reabsorbed with an efficiency comparable to L-carnitine, and these reabsorption were inhibited by 1 mM L-carnitine, suggesting that the interaction of L-carnitine with PC and VC reabsorption would be responsible for renal handling of these acylcarnitines in rats.

Involvement of recognition and interaction of carnitine transporter in the decrease of L-carnitine concentration induced by pivalic acid and valproic acid.

Purpose: Prodrugs with pivalic acid and valproic acid decrease L-carnitine concentration in plasma and tissues by urinary excretion of acylcarnitine as pivaloylcarnitine (PC) and valproylcarnitine (VC), respectively. We investigated the role of the Na+/L-carnitine cotransporter in the porcine kidney epithelial cell line, LLC-PK1 for the decrease of L-carnitine concentration.

Methods: The uptake of L-[3H]carnitine, acetyl-L-[3H]carnitine (AC), L-[3H]PC and L-[3H]VC were investigated in LLC-PK1 cells seeded in a 6-well culture plate.

Distinct transport activity of tetraethylammonium from L-carnitine in rat renal brush-border membranes.

We investigated the contribution of the Na(+)/L-carnitine cotransporter in the transport of tetraethylammonium (TEA) by rat renal brush-border membrane vesicles. The transient uphill transport of L-carnitine was observed in the presence of a Na(+) gradient. The uptake of L-carnitine was of high affinity (K(m)=21 microM) and pH dependent.