Cell-Based Microfluidic Device Utilizing Cell Sheet Technology.

The development of microelectromechanical systems has resulted in the rapid development of polydimethylpolysiloxane (PDMS) microfluidic devices for drug screening models. Various cell functions, such as the response of endothelial cells to fluids, have been elucidated using microfluidic devices. Additionally, organ-on-a-chip systems that include organs that are important for biological circulation, such as the heart, liver, pancreas, kidneys, and brain, have been developed. These organs realize the biological circulation system in a manner that cannot be reproduced by artificial organs; however, the flow channels between the organs are often artificially created by PDMS. In this study, we developed a microfluidic device consisting only of cells, by combining cell sheet technology with microtitanium wires. Microwires were placed between stacked fibroblast cell sheets, and the cell sheets adhered to each other, after which the microwires were removed leaving a luminal structure with a size approximately equal to the arteriolar size. The lumen structure was constructed using wires with diameters of 50, 100, 150, and 200 µm, which were approximations of the arteriole diameters. Furthermore, using a perfusion device, we successfully perfused the luminal structure created inside the cell sheets. The results revealed that a culture solution can be supplied to a cell sheet with a very high cell density. The biofabrication technology proposed in this study can contribute to the development of organ-on-a-chip systems.

Investigation of Potential Pharmacokinetic Interactions Between Teneligliptin and Metformin in Steady-state Conditions in Healthy Adults.

PURPOSE: We assessed the effects of coadministration of metformin and teneligliptin on their pharmacokinetics in steady-state conditions relative to the administration of either drug alone. METHODS: This was a Phase I, single-center, open-label, 2-way parallel-group study in healthy male and female subjects. Subjects in group 1 (n = 20) were administered 40 mg of teneligliptin once daily for 5 days, and 850 mg of metformin BID was added to ongoing teneligliptin for an additional 3 days. The subjects in group 2 (n = 20) were administered 850 mg of metformin BID for 3 days, and 40 mg of teneligliptin once daily was added to ongoing metformin for an additional 5 days. Pharmacokinetic outcomes were the AUC0-τ and Cmax of metformin and teneligliptin when administered alone or in combination. FINDINGS: Ten male and 10 female subjects participated in each group (mean ± SD age 39.2 ± 11.6 years [range, 19-63 years] in group 1, 47.6 ± 11.9 years [27-64] in group 2; mean ± SD BMI 23.36 ± 2.45 in group 1, 24.56 ± 2.54 in group 2). One female subject in each group was withdrawn because of an adverse event (AE) (vomiting). All 20 subjects in each group were included in the safety analyses, and 19 subjects in each group were included in the pharmacokinetic analyses. The geometric least square means ratio (teneligliptin plus metformin/teneligliptin alone) for Cmax and the AUC0-τ for teneligliptin were 0.907 (90% CI, 0.853-0.965) and 1.042 (90% CI, 0.997-1.089), respectively. The geometric least square means ratio (metformin plus teneligliptin/metformin alone) for the Cmax and AUC0-τ for metformin were 1.057 (90% CI, 0.974-1.148) and 1.209 (90% CI, 1.143-1.278). The 90% CIs were within the prespecified threshold for equivalence (0.80-1.25), except for the AUC0-τ for metformin, which was increased by teneligliptin by 20% relative to metformin alone. In group 1, nine subjects experienced 25 AEs during treatment with teneligliptin alone and 10 subjects experienced 15 AEs during treatment with teneligliptin plus metformin. In group 2, eight subjects experienced 11 AEs during treatment with metformin alone and 11 subjects experienced 18 AEs during treatment with metformin plus teneligliptin. Two AEs in each treatment group were rated as severe. Results of in vitro experiments suggest that teneligliptin-mediated inhibition of organic cation transporter-2 does not increase metformin exposure. IMPLICATIONS: Coadministration of teneligliptin and metformin was well tolerated by these healthy subjects during the 8-day treatment period. Coadministration with metformin did not affect the pharmacokinetics of teneligliptin. Although coadministration with teneligliptin increased exposure to metformin, this change is unlikely to be clinically relevant. European Clinical Trials Database identifier: 2007-001511-29.

Effect of ketoconazole on the pharmacokinetics of the dipeptidyl peptidase-4 inhibitor teneligliptin: an open-label study in healthy white subjects in Germany.

OBJECTIVE: The aim of this study was to examine the effect of ketoconazole, a potent cytochrome P450 (CYP) 3A4 and P-glycoprotein (P-gp) inhibitor, on teneligliptin pharmacokinetics and to evaluate the safety of combined administration of teneligliptin with ketoconazole. METHODS: This open-label, fixed-sequence study was conducted in 16 healthy adult volunteers in Germany. On day 1, under fasting conditions, 20 mg of teneligliptin was administered to evaluate the pharmacokinetics of teneligliptin alone. For 3 days (days 8-10), 400 mg of ketoconazole was administered once daily. On day 11, teneligliptin 20 mg and ketoconazole 400 mg were concurrently administered, and for 2 days (days 12 and 13), ketoconazole was administered once daily. The pharmacokinetic parameters (Cmax, Tmax, AUC, terminal t½, apparent total plasma clearance, and Vd during the terminal phase) of teneligliptin on days 1 and 11 were calculated. The safety profile was evaluated based on adverse events and clinical findings. To investigate the role of human P-gp in membrane permeation of teneligliptin, an in vitro study was performed to measure the transcellular transport of teneligliptin across monolayers of human P-gp-expressing cells and control cells. RESULTS: For Cmax and AUC, the geometric least squares mean ratios (90% CIs) of teneligliptin with ketoconazole to teneligliptin alone were 1.37 (1.25-1.50) and 1.49 (1.39-1.60), respectively. There was no change in t½ of the terminal elimination phase. In addition, the tolerability of teneligliptin coadministered with ketoconazole was acceptable. The in vitro study revealed corrected efflux ratios for teneligliptin of 6.81 and 5.27 at teneligliptin concentrations of 1 and 10 µM, respectively. CONCLUSIONS: Because the exposure to teneligliptin in combined administration with ketoconazole, a potent CYP3A4 and P-gp inhibitor, was less than twice that of administration of teneligliptin alone, it is suggested that combined administration of teneligliptin with drugs and foods that inhibit CYP3A4 should not cause a marked increase in exposure. The results of our in vitro study suggest that teneligliptin is a substrate of P-gp. CLINICAL TRIAL REGISTRATION: EudraCT No. 2009-016652-51.

The effect of AST-120 on the single-dose pharmacokinetics of metoprolol extended-release tablets in healthy subjects.

BACKGROUND: This was a randomized, open-label, three-way crossover study to assess the effects of AST-120 (an orally administered spherical carbon adsorbent acting in the gastrointestinal tract without systemic circulation) on the single-dose pharmacokinetics of metoprolol in an extended-release formulation (metoprolol ER) in healthy volunteers. METHODS: A total of 34 subjects were singly administered metoprolol ER alone (A), and metoprolol ER in combination with AST-120 simultaneously (B) and 1 h later (C). RESULTS: The total exposure was more significantly reduced in both treatments B and C than that in treatment A; the geometric mean ratios of area under the curve extrapolated to infinity (AUC0-∞) for B/A and C/A were reduced by approximately 30% in both treatments B and C. Maximum observed plasma concentration (Cmax) of metoprolol in treatment B significantly decreased, whereas Cmax in treatment C was slightly decreased. AST-120 treatment was unlikely to affect apparent first-order terminal elimination half-life (T1/2) of metoprolol significantly. Reduction in heart rate and blood pressure readings were similar across the treatment periods. Coadministration of AST-120 and metoprolol ER was safe and was well tolerated. CONCLUSIONS: Because AST-120 reduced gastrointestinal absorption of metoprolol ER, careful monitoring of heart rate and blood pressure is recommended in coadministration of AST-120 with metoprolol ER.

Anticoagulation with argatroban for elective percutaneous coronary intervention: population pharmacokinetics and pharmacokinetic-pharmacodynamic relationship of coagulation parameters.

The synthetic direct thrombin inhibitor argatroban has a rapid onset and offset of anticoagulation. However, there are no data about the pharmacokinetic-pharmacodynamic (PK-PD) relationship of argatroban in patients undergoing contemporary percutaneous coronary intervention (PCI) and no data about other coagulation parameters than activated clotting time (ACT) in this setting. In the ARG-E04-trial, 140 patients were randomly assigned to argatroban (250, 300, or 350 µg/kg as bolus before PCI, followed by 15, 20, or 25 µg/kg/min infusion) or unfractionated heparin (70-100 IU/kg bolus). A 2-compartment model with first-order elimination adequately described the pharmacokinetic profile of argatroban over all 3 dosing groups. Clearance (CL) and distribution volumes (V1 and V2) were 21 L/h, 9.2 L, and 6.6 L, respectively. A significant sigmoidal E(max) relationship was established between the argatroban plasma concentration and the response in ACT and the endogenous thrombin potential (ETP), whereas the response in activated partial thromoplastin time (aPTT), ecarin time (ECA-T), and prothrombinase-induced clotting time (PiCT) could be described by a nonsigmoidal E(max) model. This study proves a relatively small interindividual variability of both PK and PK-PD properties of argatroban even at high doses and supports the profile of argatroban as a drug with a predictive dose-effect relationship and therefore good controllability.

Autoinduction of MKC-963 [(R)-1-(1-cyclohexylethylamino)-4-phenylphthalazine] metabolism in healthy volunteers and its retrospective evaluation using primary human hepatocytes and cDNA-expressed enzymes.

MKC-963, (R)-1-(1-cyclohexylethylamino)-4-phenylphthalazine, a potent inhibitor of platelet aggregation, was synthesized and used in clinical trials in the 1990s. In the process of clinical study, it was found that urinary excretion ratios for 6beta-hydroxycortisol and free cortisol increased significantly in parallel with decreases in the plasma concentrations of MKC-963 after repeated oral administration of the compound to healthy volunteers. These findings suggested that MKC-963 caused autoinduction (defined as the ability of a drug to induce enzymes that enhance its own metabolism, resulting in dispositional tolerance) in humans, and clinical studies using the compound were stopped. This experience prompted us to reevaluate the effects of this compound on CYP3A4 using primary human hepatocytes and cDNA-expressed human cytochrome P450 (P450) enzymes to determine whether the autoinduction of MKC-963 metabolism in humans could have been predicted if these in vitro systems had been used for the evaluation of MKC-963 in the preclinical study. The results of in vitro study showed that MKC-963 increased CYP3A4 mRNA expression level and activity of testosterone 6beta-hydroxylation to extents similar to those observed with rifampicin in primary human hepatocytes. In addition, approximately 90% of the MKC-963 metabolism in human liver microsomes was estimated to be attributable to CYP3A4. These in vitro findings are in good agreement with the results of clinical study, suggesting that studies using human hepatocytes and cDNA-expressed human P450s are useful for assessing the autoinductive nature of compounds under development before starting clinical studies.