Transporter-Mediated Hepatic Uptake Plays an Important Role in the Pharmacokinetics and Drug-Drug Interactions of Montelukast

Mechanistic Determinants of Daprodustat Drug-Drug Interactions and Pharmacokinetics in Hepatic Dysfunction and Chronic Kidney Disease: Significance of OATP1B-CYP2C8 Interplay

Daprodustat is the first oral hypoxia-inducible factor prolyl hydroxylase inhibitor approved recently for the treatment of anemia caused by chronic kidney disease (CKD) in adults receiving dialysis. We evaluated the role of organic anion transporting polypeptide (OATP)1B-mediated hepatic uptake transport in the pharmacokinetics (PKs) of daprodustat using in vitro and in vivo studies, and physiologically-based PK (PBPK) modeling of its drug-drug interactions (DDIs) with inhibitor drugs. In vitro, daprodustat showed specific transport by OATP1B1/1B3 in the transfected cell systems and primary human and monkey hepatocytes. A single-dose oral rifampin (OATP1B inhibitor) reduced daprodustat intravenous clearance by a notable 9.9 ± 1.2-fold (P < 0.05) in cynomolgus monkeys. Correspondingly, volume of distribution at steady-state was also reduced by 5.0 ± 1.1-fold, whereas the half-life change was minimal (1.5-fold), corroborating daprodustat hepatic uptake inhibition by rifampin. A PBPK model accounting for OATP1B-CYP2C8 interplay was developed, which well described daprodustat PK and DDIs with gemfibrozil (CYP2C8 and OATP1B inhibitor) and trimethoprim (weak CYP2C8 inhibitor) within 25% error of the observed data in healthy subjects. About 18-fold increase in daprodustat area under the curve (AUC) following gemfibrozil treatment was found to be associated with strong CYP2C8 inhibition and moderate OATP1B inhibition. Moreover, PK modulation in hepatic dysfunction and subjects with CKD, in comparison to healthy control, was well-captured by the model. CYP2C8 and/or OATP1B inhibitor drugs (e.g., gemfibrozil, clopidogrel, rifampin, and cyclosporine) were predicted to perpetrate moderate-to-strong DDIs in healthy subjects, as well as, in target CKD population. Daprodustat can be used as a sensitive CYP2C8 index substrate in the absence of OATP1B modulation.

Open-label, drug-drug interaction study between the HIV-1 maturation inhibitor GSK3640254 and a metabolic probe cocktail in healthy participants

AIMS

GSK3640254 (GSK'254) is an HIV-1 maturation inhibitor with pharmacokinetics (PK) supporting once-daily dosing. GSK'254 will be co-administered with cytochrome P450 enzyme substrates and drug transporters, including other antiretrovirals, in people living with HIV-1 (PLWH).

METHODS

In this open-label study, healthy participants received a single dose of a cocktail of eight cytochrome P450 and transporter probe substrates on Day 1, followed by a 10-day washout before receiving GSK'254 200 mg once daily from Days 11 to 20 and a single dose of cocktail + GSK'254 200 mg on Day 21. Geometric least-squares mean ratios and 90% confidence intervals were obtained using linear mixed-effects models. Adverse events (AEs) were monitored.

RESULTS

Of 20 participants enrolled, 19 completed the study. Plasma concentrations of all cocktail substrates were generally similar with or without GSK'254 co-administration. All 90% confidence intervals around geometric least-squares mean ratios for cocktail substrate PK parameters indicated no to weak interactions. Steady-state plasma GSK'254 concentrations were achieved by Day 17 and maintained through Day 21. Nine participants (45%) reported 17 AEs; most (88%) were grade 1. Two grade 2 treatment-related AEs (maculopapular rash [leading to withdrawal] and papular rash) were reported during GSK'254 administration alone.

CONCLUSIONS

Co-administration of GSK'254 with a metabolic probe cocktail in healthy participants indicated very low risk of clinically relevant effect on PK of any substrates or associated metabolites. No new safety/tolerability concerns were identified. These results support ongoing phase IIb and planned phase III studies of GSK'254 in people living with HIV-1.

Plasma Protein Binding Refinement of the Extended Clearance Classification System: Subclasses for Predicting Hepatic Uptake or Renal Clearance for Classes 1B and 3B

BACKGROUND AND OBJECTIVES

The Extended Clearance Classification System (ECCS) was established to facilitate the timely anticipation of clearance rate determination according to the physicochemical characteristics of a given compound and in vitro passive membrane permeability. Unfortunately, distinguishing between renal and hepatic uptake clearance mechanisms using ECCS class 3B is not possible. We determined the effects of plasma protein binding (PPB) on major hepatic organic anion transporting polypeptide (OATP) and renal organic anion transporter (OAT) substrates. A modified ECCS could predict when renal or hepatic uptake mechanisms were the main clearance rate determinants (accounting for ≥ 70% of total clearance).

METHODS

A dataset of 66 human OATP and 41 OAT substrates was analyzed to determine the effect of PPB. A total of 63 acidic and zwitterionic, and high-molecular-weight (MW > 400 Da) compounds, including 50 drugs in ECCS classes 1B and 3B, were reanalyzed considering their PPB.

RESULTS

Statistical analyses revealed that hepatic uptake transporter (OATP1B1 and OATP1B3) substrates possess a high PPB rate of ≥ 90%, whereas OAT1 and/or OAT3 substrates possess low PPB rates of < 90%. By analyzing the 63 drugs on the basis of their PPB, the active hepatic uptakes of acids and zwitterions were determined to be the main clearance mechanisms, with PPB ≥ 90%, whereas renally eliminated drugs exhibited limited PPB (< 90%).

CONCLUSIONS

Therefore, PPB is an effective parameter for defining clearance rate determination for acidic and zwitterionic drugs with high MWs. Using PPB as an additional parameter in ECCS, clearance mechanisms for class 1B and 3B compounds can be predicted, and OATP and OAT substrates may be readily distinguished.

Inhibition of CYP2C8 by Acyl Glucuronides of Gemfibrozil and Clopidogrel: Pharmacological Significance, Progress and Challenges

The lipid-regulating drug gemfibrozil is a useful medication for reducing high cholesterol and triglycerides in the blood. In addition to oxidation, it undergoes extensive glucuronidation to produce gemfibrozil acyl glucuronide, which is a known mechanism-based inactivator of cytochrome P450 (CYP) 2C8. Such selective and time-dependent inhibition results in clinically important drug–drug interactions (DDI) with the drugs metabolized by CYP2C8. Similarly, the acyl glucuronide of clopidogrel, a widely used antiplatelet agent, is a potent time-dependent inhibitor of CYP2C8 that demonstrated significant DDI with the substrates of CYP2C8. Current progress in atomic-level understanding mostly involves studying how different drugs bind and undergo oxidation in the active site of CYPs. It is not clear how an acyl glucuronide metabolite of the drug gemfibrozil or clopidogrel interacts in the active site of CYP2C8 and selectively inhibit the enzyme. This mini-review summarizes the current knowledge on some of the important clinical DDI caused by gemfibrozil and clopidogrel due to the inhibition of CYP2C8 by acyl glucuronide metabolites of these drugs. Importantly, it examines recent developments and potential applications of structural biology tools to elucidate the binding and orientation of gemfibrozil acyl glucuronide and clopidogrel acyl glucuronide in the active site near heme that contributes to the inhibition and inactivation of CYP2C8.

Synthesis, Characterization and In Vitro Evaluation of Chitosan Nanoparticles Physically Admixed with Lactose Microspheres for Pulmonary Delivery of Montelukast

This study aimed to synthesise montelukast-loaded polymeric nanoparticles via the ionic gelation method using chitosan as a natural polymer and tripolyphosphate as a crosslinking agent. Tween 80, hyaluronic acid and leucine were added to modify the physicochemical properties of nanoparticles, reduce the nanoparticles’ uptake by alveolar macrophages and improve powder aerosolisation, respectively. The nanoparticles ranged from 220 nm to 383 nm with a polydispersity index of ≤0.50. The zeta potential of nanoparticles ranged from 11 mV to 22 mV, with a drug association efficiency of 46–86%. The simple chitosan nanoparticles (F2) were more spherical in comparison to other formulations (F4–F6), while the roughness of hyaluronic acid (F5) and leucine (F6) added formulations was significantly high er than F2 and Tween 80 added formulation (F4). The DSC and FTIR analysis depict that the physical and chemical properties of the drug were preserved. The release of the drugs from nanoparticles was more sustained in the case of F5 and F6 when compared to F2 and F4 due to the additional coating of hyaluronic acid and leucine. The nanoparticles were amorphous and cohesive and prone to exhalation due to their small size. Therefore, nanoparticles were admixed with lactose microspheres to reduce particle agglomeration and improve powder dispersion from a dry powder inhaler (DPI). The DPI formulations achieved a dispersed fraction of 75 to 90%, a mass median aerodynamic diameter (MMAD) of 1–2 µm and a fine particle fraction (FPF) of 28–83% when evaluated using the Anderson cascade impactor from Handihaler®. Overall, the montelukast-loaded nanoparticles physically admixed with lactose microspheres achieved optimum deposition in the deep lung for potential application in asthmatic patients.

Pharmacokinetics, Mass Balance, Metabolism, and Excretion of the Liver-Targeted Acetyl-CoA Carboxylase Inhibitor PF-05221304 (Clesacostat) in Humans

The disposition of the hepatoselective ACC inhibitor PF-05221304 (Clesacostat) was studied after a single 50-mg oral dose of [14C]-PF-05221304 to healthy human subjects.Mass balance was achieved with 89.9% of the administered dose recovered in urine and faeces, over the 11-day study period. The total administered radioactivity excreted in faeces and urine was 81.7% and 8.2%, respectively. Unchanged PF-05221304 accounted for 35.6% of the radioactive dose in faeces, suggesting ∼64% of the administered dose was absorbed.PF-05221304 was principally metabolized via oxidative and reductive pathways involving: (a) N-dealkylation, (b) isopropyl group monohydroxylation to yield enantiomeric metabolites (M2a and M2b), (c) hydroxylation on the 3-azaspiro[5.5]undecan-8-one moiety to metabolites M5 and 519c, and (d) carbonyl group reduction to enantiomeric alcohol metabolites M3, and M4. Secondary metabolites (521a, 521b, and 533), derived from a combination of oxidation and reduction of the primary metabolites accounted for ∼14.8% of the dose. In plasma, unchanged PF-05221304 represented 96.1% circulating radioactivity. Metabolites M1, M2b, and M2a represented 1.94, 1.76, and 0.18% of circulating radioactivity, respectively.Overall, these data suggest that PF-05221304 is well absorbed in humans and eliminated largely via phase I metabolism.

Antifungal Drugs TDM: Trends and Update

PURPOSE

The increasing burden of invasive fungal infections results in growing challenges to antifungal (AF) therapeutic drug monitoring (TDM). This review aims to provide an overview of recent advances in AF TDM.

METHODS

We conducted a PubMed search for articles during 2016-2020 using "TDM" or "pharmacokinetics" or "drug-drug-interaction" with "antifungal," consolidated for each AF. Selection was limited to English language articles with human data on drug exposure.

RESULTS

More than 1000 articles matched the search terms. We selected 566 publications. The latest findings tend to confirm previous observations in real-life clinical settings. The pharmacokinetic variability related to special populations is not specific but must be considered. AF benefit-to-risk ratio, drug-drug interaction (DDI) profiles, and minimal inhibitory concentrations for pathogens must be known to manage at-risk situations and patients. Itraconazole has replaced ketoconazole in healthy volunteers DDI studies. Physiologically based pharmacokinetic modeling is widely used to assess metabolic azole DDI. AF prophylactic use was studied more for Aspergillus spp. and Mucorales in oncohematology and solid organ transplantation than for Candida (already studied). Emergence of central nervous system infection and severe infections in immunocompetent individuals both merit special attention. TDM is more challenging for azoles than amphotericin B and echinocandins. Fewer TDM requirements exist for fluconazole and isavuconazole (ISZ); however, ISZ is frequently used in clinical situations in which TDM is recommended. Voriconazole remains the most challenging of the AF, with toxicity limiting high-dose treatments. Moreover, alternative treatments (posaconazole tablets, ISZ) are now available.

CONCLUSIONS

TDM seems to be crucial for curative and/or long-term maintenance treatment in highly variable patients. TDM poses fewer cost issues than the drugs themselves or subsequent treatment issues. The integration of clinical pharmacology into multidisciplinary management is now increasingly seen as a part of patient care.

OATP2B1 - The underrated member of the organic anion transporting polypeptide family of drug transporters?

The organic anion transporting polypeptide 2B1 (OATP2B1) was one of the first cloned members of the SLCO family. However, its physiological and pharmacological role is still poorly understood, and object of a current debate on the transporter's relevance. Within this commentary, we summarize the data currently available on the transporter's expression and its substrates and highlight the strength and difficulties of the methods that have been applied to gather these data. The conclusion drawn from these findings was that OATP2B1 due to its intestinal expression is most likely involved in oral drug absorption of its substrate and therefore prone for interactions. This has been tested in in vivo drug interaction and/or pharmacogenetic studies. While some of these support the notion of OATP2B1 being of relevance in drug absorption, the pharmacogenetic findings are rather inconclusive. We will explain our thoughts why OATP2B1 may not influence the general systemic pharmacokinetic of certain substrates, but possibly local distribution processes, like the transfer across the blood-brain-barrier. Besides the pharmacokinetic aspects, there are data on endogenous molecules like coproporphyrins and sulfated steroids. Therefore, we will also highlight possible physiological roles of OATP2B1, which are driven by its expression pattern in the tubular cells of the kidney as well as its expression in the blood brain barrier. Finally we also deal with the advantages and disadvantages in the use of animal models to decipher the role of OATP2B1 in pharmacokinetics of its substrates and beyond.

Organic Anion-Transporting Polypeptide 1B1/1B3-Mediated Hepatic Uptake Determines the Pharmacokinetics of Large Lipophilic Acids: In Vitro-In Vivo Evaluation in Cynomolgus Monkey

It is generally presumed that uptake transport mechanisms are of limited significance in hepatic clearance for lipophilic or high passive-permeability drugs. In this study, we evaluated the mechanistic role of the hepato-selective organic anion-transporting polypeptides (OATPs) 1B1/1B3 in the pharmacokinetics of compounds representing large lipophilic acid space. Intravenous pharmacokinetics of 16 compounds with molecular mass ∼400-730 Da, logP ∼3.5-8, and acid pKa <6 were obtained in cynomolgus monkey after dosing without and with a single-dose rifampicin-OATP1B1/1B3 probe inhibitor. Rifampicin (30 mg/kg oral) significantly (P < 0.05) reduced monkey clearance and/or steady-state volume of distribution (VDss) for 15 of 16 acids evaluated. Additionally, clearance of danoprevir was reduced by about 35%, although statistical significance was not reached. A significant linear relationship was noted between the clearance ratio (i.e., ratio of control to treatment groups) and VDss ratio, suggesting hepatic uptake contributes to the systemic clearance and distribution simultaneously. In vitro transport studies using primary monkey and human hepatocytes showed uptake inhibition by rifampicin (100 µM) for compounds with logP ≤6.5 but not for the very lipophilic acids (logP > 6.5), which generally showed high nonspecific binding in hepatocyte incubations. In vitro uptake clearance and fraction transported by OATP1B1/1B3 (f_t,OATP1B) were found to be similar in monkey and human hepatocytes. Finally, for compounds with logP ≤6.5, good agreement was noted between in vitro f_t,OATP1B and clearance ratio (as well as VDss ratio) in cynomolgus monkey. In conclusion, this study provides mechanistic evidence for the pivotal role of OATP1B-mediated hepatic uptake in the pharmacokinetics across a wide, large lipophilic acid space. SIGNIFICANCE STATEMENT: This study provides mechanistic insight into the pharmacokinetics of a broad range of large lipophilic acids. Organic anion-transporting polypeptides 1B1/1B3-mediated hepatic uptake is of key importance in the pharmacokinetics and drug-drug interactions of almost all drugs and new molecular entities in this space. Diligent in vitro and in vivo transport characterization is needed to avoid the false negatives often noted because of general limitations in the in vitro assays while handling compounds with such physicochemical attributes.

Predicting the Human Hepatic Clearance of Acidic and Zwitterionic Drugs

Prospective predictions of human hepatic clearance for anionic/zwitterionic compounds, which are oftentimes subjected to transporter-mediated uptake, are challenging in drug discovery. We evaluated the utility of preclinical species, rats and cynomolgus monkeys [nonhuman primates (NHPs)], to predict the human hepatic clearance using a diverse set of acidic/zwitterionic drugs. Preclinical clearance data were generated following intravenous dosing in rats/NHPs and compared to the human clearance data (n = 18/27). Single-species scaling of NHP clearance with an allometric exponent of 0.50 allowed for good prediction of human clearance (fold error ∼2.1, bias ∼1.0), with ∼86% predictions within 3-fold. In comparison, rats underpredicted the clearance of lipophilic acids, while overprediction was noted for hydrophilic acids. Finally, an in vitro clearance assay based on human hepatocytes, which is routinely used in discovery setting, markedly underpredicted human clearance (bias ∼0.12). Collectively, this study provides insights into the usefulness of the preclinical models in enabling pharmacokinetic optimization for acid/zwitterionic drug candidates.

A simple and sensitive HPLC-MS/MS assay for the quantitation of montelukast in cell-based systems in vitro pulmonary drug permeability study

Montelukast is a potent and selective antagonist of the cysteinyl leukotriene receptor 1 subtype (CysLT1) and widely used in the form of oral tablets and granules for asthma prophylaxis and treatment. Recently, due to the pulmonary inhaled administration can limit montelukast distribution in the systemic circulation, avoid the first-pass metabolism and have better therapeutic effects in respiratory disease treatment, explore alternative routes of administration, like delivery of montelukast via an inhaled, is a new research trend for montelukast. The aim of the current study was to develop and validate a simple, accurate, highly sensitive and selective liquid chromatography-tandem mass spectrometry method (LC-MS/MS) for determination of montelukast in an in vitro cell-based pulmonary pharmacokinetics system model, which can be used to be a better understanding the fate of inhaled montelukast in the lungs. In this study, montelukast was extracted by protein precipitation with acetonitrile containing labeled montelukast. The chromatography was performed on an Agilent Eclipse plus C8 column (4.6 mm × 100 mm, 3.5 μm, Darmstadt, Germany) operating at 35 ◦C. The mobile phase consisted of acetonitrile: 20 mM ammonium formate buffer (80: 20, v/v), was delivered at a flow rate of 0.5 mL/min. montelukast and the internal standard were both eluted at 4.2 min. A linear (1/x²) relationship was used to perform the calibration over an analytical range from 0.5 to 600 ng/mL. The intra- and inter-batch precision expressed as CV for four QC samples including LLOQ range from 1.14 % to 6.25 %. The intra- and inter-batch accuracy for four concentrations of montelukast were in the range of 95.19%-104.1%. All the values for accuracy and precision were within the acceptance range. The method met all the bioanalytical method validation requirements by ICH and was suitable for the assay of montelukast which in the in vitro cell-based pulmonary pharmacokinetics system model.

Pilot Study of Peak Plasma Concentration After High-Dose Oral Montelukast in Children With Acute Asthma Exacerbations

Acute asthma exacerbations are primarily due to airway inflammation and remain one of the most frequent reasons for childhood hospitalizations. Although systemic corticosteroids remain the mainstay of therapy because of their anti-inflammatory properties, not all inflammatory pathways are responsive to systemic corticosteroids, necessitating hospital admission for further management. Cysteinyl leukotrienes (LTs) are proinflammatory mediators that play an important role in systemic corticosteroids non-responsiveness. Montelukast is a potent LT-receptor antagonist, and an intravenous preparation caused rapid, sustained improvement of acute asthma exacerbations in adults. We hypothesized that a 30-mg dose of oral montelukast achieves peak plasma concentrations (C_max ), comparable to the intravenous preparation (1700 ng/mL) and would be well tolerated in 15 children aged 5 to 12 years with acute asthma exacerbations. After administration of montelukast chewable tablets, blood samples were collected at 0, 15, 30, 45, 60, 120, 180, and 240 minutes. Plasma was separated and frozen at -80°C until analysis for montelukast concentration using liquid chromatography- tandem mass spectrometry. Median time to C_max (t_max ) was 3.0 hours. Six participants (40%) achieved C_max of 1700 ng/mL or higher. However, there was high interindividual variability in peak plasma concentration (median C_max of 1378 ng/mL; range, 16-4895 ng/mL). No participant had side effects or adverse events. Plasma concentrations from this pilot study support the design of a weight-based dose-finding study aimed at selecting an optimal dose for future clinical trials to assess the efficacy of high-dose oral montelukast in children with moderate to severe asthma exacerbations.

Potential drug-drug interactions associated with drugs currently proposed for COVID-19 treatment in patients receiving other treatments

Patients with COVID-19 are sometimes already being treated for one or more other chronic conditions, especially if they are elderly. Introducing a treatment against COVID-19, either on an outpatient basis or during hospitalization for more severe cases, raises the question of potential drug-drug interactions. Here, we analyzed the potential or proven risk of the co-administration of drugs used for the most common chronic diseases and those currently offered as treatment or undergoing therapeutic trials for COVID-19. Practical recommendations are offered, where possible.

Modelled plasma concentrations of pemafibrate with co-administered typical cytochrome P450 inhibitors clopidogrel, fluconazole or clarithromycin predicted by physiologically based pharmacokinetic modelling in virtual populations

Oral antidyslipidaemic drug pemafibrate is cleared from human plasma via hepatic uptake by organic anion transporting polypeptide (OATP) 1B1 and oxidation by cytochromes P450 (P450) 2C8, 2C9 and 3A4. The pharmacokinetic profiles of pemafibrate with virtual administrations of P450 inhibitors and/or disease interactions were generated using a physiologically based pharmacokinetic (PBPK) model previously established for co-administration of pemafibrate with OATP1B1 inhibitors. This PBPK model was validated in the current study using reported maximum pemafibrate plasma concentrations and areas under the curve from interaction studies in healthy subjects co-administered with clopidogrel (P450 2C8 inhibitor), fluconazole (P450 2C9/3A4 inhibitor) or clarithromycin (P450 3A4 inhibitor). Virtual co-administrations of pemafibrate with clopidogrel, fluconazole or clarithromycin increased the predicted plasma exposures of pemafibrate 1.4-1.7-fold, 1.2-1.4-fold and 2.9-11-fold, respectively, in subjects with or without moderate or severe renal impairment or Child-Pugh A or B liver cirrhosis. Some of the exposure-enhancing effects of clarithromycin may originate from its inhibitory potential toward OATP1B1, because the estimated effects of itraconazole (a P450 3A4 inhibitor) were only minor. Simulations using the current PBPK model in groups of virtual subjects with or without renal or hepatic impairment revealed modified pharmacokinetic profiles for pemafibrate following co-administration of typical P450 inhibitors.

Developmental Pharmacogenetics of SLCO2B1 on Montelukast Pharmacokinetics in Chinese Children

Background

Montelukast, a potent oral selective leukotriene-receptor antagonist, inhibits the action of cysteinyl-leukotriene in patients with asthma. Although pharmacokinetic studies of montelukast have been reported in Caucasian adults and children, and showed large inter-individual variability on pharmacokinetics, none of these studies has been explored in Chinese children. Given the potential inter-ethnic difference, the purpose of the present study was to evaluate the effects of developmental factors and pharmacogenetics of CYP2C8 and SLCO2B1 on montelukast clearance in Chinese pediatric patients.

Methods

After the administration of montelukast, blood samples were collected from children and plasma concentrations were determined using an adapted micro high-performance liquid chromatography coupled with the fluorescence detection (HPLC-FLD) method. A previously published pharmacokinetic model was validated using the opportunistic pharmacokinetic samples, and individual patient’s clearance was calculated using the validated model. Population pharmacokinetic analysis was performed using a nonlinear mixed-effects model approach (NONMEM V 7.2.0) and variants of CYP2C8 and SLCO2B1 were genotyped.

Results

Fifty patients (age range: 0.7–10.0 years) with asthma were enrolled in this study. The clearance of montelukast was significantly higher in children with the SLCO2B1 c.935GA and c.935AA genotypes compared with that of children with the SLCO2B1 c.935GG genotype (0.94 ± 0.26 versus 0.77 ± 0.21, p = 0.020). The patient’s weight was also found to be significantly corrected with montelukast clearance (p <0.0001).

Conclusion

The developmental pharmacology of montelukast in Chinese children was evaluated. Weight and SLCO2B1 genotype were found to have independent significant impacts on the clearance of montelukast.

Involvement of organic anion-transporting polypeptides and organic cation transporter in the hepatic uptake of jatrorrhizine

Jatrorrhizine possesses a wide spectrum of pharmacological activities. However, the mechanism underlying hepatic uptake of jatrorrhizine remains unclear.Rat liver slices, isolated rat hepatocytes and human embryonic kidney 293 (HEK293) cells stably expressing human organic anion-transporting polypeptide (OATP) and organic cation transporter (OCT) were used to evaluate the hepatic uptake of jatrorrhizine in this study.Uptake of jatrorrhizine in rat liver slices and isolated rat hepatocytes was significantly inhibited by glycyrrhizic acid (Oatp1b2 inhibitor) and prazosin (Oct1 inhibitor), but not by ibuprofen (Oatp1a1 inhibitor) or digoxin (Oatp1a4 inhibitor). Uptake of jatrorrhizine in OATP1B3 and OCT1-HEK293 cells indicated a saturable process with the K_m of 8.20 ± 1.28 and 4.94 ± 0.55 μM, respectively. However, the transcellular transport of jatrorrhizine in OATP1B1-HEK293 cells was not observed. Rifampicin (OATP inhibitor) for OATP1B3-HEK293 cells and prazosin for OCT1-HEK293 cells could inhibit the uptake of jatrorrhizine with the IC₅₀ of 5.49 ± 1.05 and 2.77 ± 0.72 μM, respectively.The above data indicate that hepatic uptake of jatrorrhizine is involved in both OATP and OCT, which may have important roles in jatrorrhizine liver disposition and potential drug-drug interactions.

In vivo hepatic clearance of lipophilic drugs predicted by in vitro uptake data into cryopreserved hepatocytes suspended in sera of rats, guinea pigs, monkeys and humans

Evaluation of uptake of lipophilic acid compounds into hepatocytes was an unresolved drug development issue because of their adsorption to cells and materials and low analytical sensitivity and accuracy in assessment of protein bindings. Uptake assays of compounds using hepatocytes suspended in serum were expected to solve these problems for prediction of in vivo hepatic clearance. Here, for compounds with high protein binding (>99%), diflunisal, montelukast, cerivastatin, telmisartan, fluvastatin and six new drug candidates, in vivo hepatic clearance predicted based on hepatic depletion and uptake (CL_{h, uptake, predicted}) data using hepatocytes in the absence and presence of sera was investigated. In vitro hepatic uptake results with hepatocytes suspended in serum improved prediction of human hepatic clearance values for highly lipophilic montelukast and telmisartan. In vivo CL_{h, uptake, predicted} values of six new highly lipophilic acid drug candidates (protein binding >99.97%) and diflunisal, montelukast and cerivastatin predicted based on hepatocytes suspended in serum were within threefold differences of their total clearance in vivo in rats, guinea pigs or monkeys, except for montelukast in monkeys (5.8-fold). These results suggest that the human hepatic uptake in hepatocytes suspended in serum is useful for prediction of CL_{h, uptake, predicted}, especially for highly lipophilic/protein binding acid compounds.

Effects of a Fixed-Dose Co-Formulation of Daclatasvir, Asunaprevir, and Beclabuvir on the Pharmacokinetics of a Cocktail of Cytochrome P450 and Drug Transporter Substrates in Healthy Subjects

Background

A fixed-dose combination of daclatasvir (DCV; hepatitis C virus NS5A inhibitor), asunaprevir (ASV; non-structural protein 3 inhibitor), and beclabuvir (BCV; non-structural protein 5B inhibitor) is approved in Japan for hepatitis C virus genotype 1.

Objective

The objective of this study was to assess the combination’s drug–drug interaction potential in vivo using a validated cocktail of eight cytochrome P450 (CYP) and transporter probes.

Methods

We conducted an open-label single-sequence study in healthy adults (n = 20) given single-dose caffeine (CYP1A2 substrate), metoprolol (CYP2D6), flurbiprofen (CYP2C9), montelukast (CYP2C8), omeprazole (CYP2C19), midazolam (CYP3A4), digoxin (P-glycoprotein), and pravastatin (organic anion-transporting polypeptide), alone or with steady-state twice-daily DCV/ASV/BCV 30/200/75 mg (with or without additional BCV 75 mg to adjust for higher exposure in hepatitis C virus infection).

Results

Daclatasvir/asunaprevir/beclabuvir did not affect CYP1A2, CYP2C8, or CYP2C9; the probe maximum observed concentration and area under the concentration–time curve extrapolated to infinite time geometric mean ratios and 90% confidence intervals were all within the 0.8–1.25 bioequivalence range. Beclabuvir showed moderate dose-dependent CYP2C19 induction; omeprazole maximum observed concentration and area under the concentration–time curve from 0 to the last quantifiable concentration were lower with additional BCV [geometric mean ratio 0.36 (90% confidence interval 0.23–0.55) and 0.34 (0.25–0.46), respectively] than without [0.57 (0.42–0.78), 0.48 (0.39–0.59)]. Weak-to-moderate CYP3A4 induction was observed, plus weak CYP2D6, P-glycoprotein, and organic anion-transporting polypeptide inhibition [maximum observed concentration and area under the concentration–time curve extrapolated to infinite time without additional BCV: midazolam 0.57 (0.50–0.65), 0.53 (0.47–0.60); metoprolol 1.40 (1.20–1.64), 1.71 (1.49–1.97); digoxin 1.23 (1.12–1.35), 1.23 (1.17–1.29); pravastatin 2.01 (1.63–2.47), 1.68 (1.43–1.97)].

Conclusions

No dose adjustments with DCV/ASV/BCV are indicated for CYP1A2, CYP2C8, CYP2C9, or P-glycoprotein substrates. CYP3A4, CYP2D6, and OATP substrates should be co-administered with caution. Co-administration with agents solely metabolized by CYP2C19 is not recommended.

Electronic supplementary material

The online version of this article (10.1007/s40268-017-0222-8) contains supplementary material, which is available to authorized users.

Clopidogrel Increases Dasabuvir Exposure With or Without Ritonavir, and Ritonavir Inhibits the Bioactivation of Clopidogrel

Dasabuvir is mainly metabolized by cytochrome P450 (CYP) 2C8 and is predominantly used in a regimen containing ritonavir. Ritonavir and clopidogrel are inhibitors of CYP3A4 and CYP2C8, respectively. In a randomized, crossover study in 12 healthy subjects, we examined the impact of clinical doses of ritonavir (for 5 days), clopidogrel (for 3 days), and their combination on dasabuvir pharmacokinetics, and the effect of ritonavir on clopidogrel. Clopidogrel, but not ritonavir, increased the geometric mean AUC_0‐∞ of dasabuvir 4.7‐fold; range 2.0–10.1‐fold (P = 8·10⁻⁷), compared with placebo. Clopidogrel and ritonavir combination increased dasabuvir AUC_0‐∞ 3.9‐fold; range 2.1–7.9‐fold (P = 2·10⁻⁶), compared with ritonavir alone. Ritonavir decreased the AUC_0‐4h of clopidogrel active metabolite by 51% (P = 0.0001), and average platelet inhibition from 51% without ritonavir to 31% with ritonavir (P = 0.0007). In conclusion, clopidogrel markedly elevates dasabuvir concentrations, and patients receiving ritonavir are at risk for diminished clopidogrel response.

Simultaneous Assessment of Transporter-Mediated Drug-Drug Interactions Using a Probe Drug Cocktail in Cynomolgus Monkey

We aim to establish an in vivo preclinical model to enable simultaneous assessment of inhibition potential of an investigational drug on clinically relevant drug transporters, organic anion-transporting polypeptide (OATP)1B, breast cancer resistance protein (BCRP), P-glycoprotein (P-gp), and organic anion transporter (OAT)3. Pharmacokinetics of substrate cocktail consisting of pitavastatin (OATP1B substrate), rosuvastatin (OATP1B/BCRP/OAT3), sulfasalazine (BCRP), and talinolol (P-gp) were obtained in cynomolgus monkey-alone or in combination with transporter inhibitors. Single-dose rifampicin (30 mg/kg) significantly (P < 0.01) increased the plasma exposure of all four drugs, with a marked effect on pitavastatin and rosuvastatin [area under the plasma concentration-time curve (AUC) ratio ∼21-39]. Elacridar, BCRP/P-gp inhibitor, increased the AUC of sulfasalazine, talinolol, as well as rosuvastatin and pitavastatin. An OAT1/3 inhibitor (probenecid) significantly (P < 0.05) impacted the renal clearance of rosuvastatin (∼8-fold). In vitro, rifampicin (10 µM) inhibited uptake of pitavastatin, rosuvastatin, and sulfasalazine by monkey and human primary hepatocytes. Transport studies using membrane vesicles suggested that all probe substrates, except talinolol, are transported by cynoBCRP, whereas talinolol is a cynoP-gp substrate. Elacridar and rifampicin inhibited both cynoBCRP and cynoP-gp in vitro, indicating potential for in vivo intestinal efflux inhibition. In conclusion, a probe substrate cocktail was validated to simultaneously evaluate perpetrator impact on multiple clinically relevant transporters using the cynomolgus monkey. The results support the use of the cynomolgus monkey as a model that could enable drug-drug interaction risk assessment, before advancing a new molecular entity into clinical development, as well as providing mechanistic insights on transporter-mediated interactions.

HPLC-high-resolution mass spectrometry with polarity switching for increasing throughput of human in vitro cocktail drug-drug interaction assay

AIM

Evaluation of HPLC-high-resolution mass spectrometry (HPLC-HRMS) full scan with polarity switching for increasing throughput of human in vitro cocktail drug-drug interaction assay.

MATERIALS & METHODS

Microsomal incubates were analyzed using a high resolution and high mass accuracy Q-Exactive mass spectrometer to collect integrated qualitative and quantitative (qual/quant) data.

RESULTS

Within assay, positive-to-negative polarity switching HPLC-HRMS method allowed quantification of eight and two probe compounds in the positive and negative ionization modes, respectively, while monitoring for LOR and its metabolites.

CONCLUSION

LOR-inhibited CYP2C19 and showed higher activity for CYP2D6, CYP2E1 and CYP3A4. Overall, LC-HRMS-based nontargeted full scan quantitation allowed to improve the throughput of the in vitro cocktail drug-drug interaction assay.

Clopidogrel but Not Prasugrel Significantly Inhibits the CYP2C8-Mediated Metabolism of Montelukast in Humans

The oxidation of montelukast is mainly mediated by cytochrome P450 (CYP) 2C8, but other mechanisms may contribute to its disposition. In healthy volunteers, we investigated the effects of two widely used P2Y₁₂ inhibitors on montelukast pharmacokinetics. Clopidogrel (300 mg on day 1 and 75 mg on day 2) increased the area under the plasma concentration–time curve (AUC) of montelukast 2.0‐fold (90% confidence interval (CI) 1.72–2.28, P < 0.001) and decreased the M6:montelukast AUC_0‐7h ratio to 45% of control (90% CI 40–50%, P < 0.001). Prasugrel (60 mg on day 1 and 10 mg on day 2) had no clinically meaningful effect on montelukast pharmacokinetics. Our results imply that clopidogrel is at least a moderate inhibitor of CYP2C8, but prasugrel is not a clinically relevant CYP2C8 inhibitor. The different interaction potentials of clopidogrel and prasugrel are important to consider when antiplatelet therapy is planned for patients at risk for polypharmacy with CYP2C8 substrates.

Predictive Performance of Physiologically Based Pharmacokinetic (PBPK) Modeling of Drugs Extensively Metabolized by Major Cytochrome P450s in Children

The accuracy of physiologically based pharmacokinetic (PBPK) model prediction in children, especially those younger than 2 years old, has not been systematically evaluated. The aim of this study was to characterize the pediatric predictive performance of the PBPK approach for 10 drugs extensively metabolized by CYP1A2 (theophylline), CYP2C8 (desloratidine, montelukast), CYP2C9 (diclofenac), CYP2C19 (esomeprazole, lansoprazole), CYP2D6 (tramadol), and CYP3A4 (itraconazole, ondansetron, sufentanil). Model performance in children was evaluated by comparing simulated plasma concentration-time profiles with observed clinical results for each drug and age group. PBPK models reasonably predicted the pharmacokinetics of desloratadine, diclofenac, itraconazole, lansoprazole, montelukast, ondansetron, sufentanil, theophylline, and tramadol across all age groups. Collectively, 58 out of 67 predictions were within 2-fold and 43 out of 67 predictions within 1.5-fold of observed values. Developed PBPK models can reasonably predict exposure in children age 1 month and older for an array of predominantly CYP metabolized drugs.

Comprehensive Pharmacogenomic Study Reveals an Important Role of UGT1A3 in Montelukast Pharmacokinetics

To identify the genetic basis of interindividual variability in montelukast exposure, we determined its pharmacokinetics and sequenced 379 pharmacokinetic genes in 191 healthy volunteers. An intronic single nucleotide variation (SNV), strongly linked with UGT1A3*2, associated with reduced area under the plasma concentration–time curve (AUC_0‐∞) of montelukast (by 18% per copy of the minor allele; P = 1.83 × 10⁻¹⁰). UGT1A3*2 was associated with increased AUC_0‐∞ of montelukast acyl‐glucuronide M1 and decreased AUC_0‐∞ of hydroxymetabolites M5R, M5S, and M6 (P < 10⁻⁹). Furthermore, SNVs in SLCO1B1 and ABCC9 were associated with the AUC_0‐∞ of M1 and M5R, respectively. In addition, a candidate gene analysis suggested that CYP2C8 and ABCC9 SNVs also affect the AUC_0‐∞ of montelukast. The found UGT1A3 and ABCC9 variants associated with increased expression of the respective genes in human liver samples. Montelukast and its hydroxymetabolites were glucuronidated by UGT1A3 in vitro. These results indicate that UGT1A3 plays an important role in montelukast pharmacokinetics, especially in UGT1A3*2 carriers.

Usefulness of Two-Compartment Model-Assisted and Static Overall Inhibitory-Activity Method for Prediction of Drug-Drug Interaction

Our study of drug-drug interaction (DDI) started with the clarification of unusually large DDI observed between ramelteon (RAM) and fluvoxamine (FLV). The main cause of this DDI was shown to be the extremely small hepatic availability of RAM (vF_h). Traditional DDI prediction assuming the well-stirred hepatic extraction kinetic ignores the relative increase of vF_h by DDI, while we could solve this problem by use of the tube model. Ultimately, we completed a simple and useful method for prediction of DDI. Currently, DDI prediction becomes more complex and difficult when examining issues such as dynamic changes in perpetrator level, inhibitory metabolites, etc. The regulatory agents recommend DDI prediction by use of some sophisticated methods. However, they seem problematic in requiring plural in vitro data that reduce the flexibility and accuracy of the simulation. In contrast, our method is based on the static and two-compartment models. The two-compartment model has advantages in that it uses common pharmacokinetics (PK) parameters determined from the actual clinical data, guaranteeing the simulation of the reference standard in DDI. Our studies confirmed that dynamic changes in perpetrator level do not make a difference between static and dynamic methods. DDIs perpetrated by FLV and itraconazole were successfully predicted by use of the present method where two DDI predictors [perpetrator-specific inhibitory activities toward CYP isoforms (pA_i, CYPs) and victim-specific fractional CYP-isoform contributions to the clearance (vf_m, CYPs)] are determined successively as shown in the graphical abstract. Accordingly, this approach will accelerate DDI prediction over the traditional methods.