Simultaneous oral therapeutic and intravenous ¹⁴C-microdoses to determine the absolute oral bioavailability of saxagliptin and dapagliflozin

The application of Phase 0 and microtracer approaches in early clinical development: past, present, and future

Phase 0 microdosing studies were introduced to the drug development community approximately 20 years ago. A microdose is defined as less than 1/100th of the dose calculated based on animal data to yield a pharmacological effect in humans, with a maximum of 100 μg, or 30 nmoles for protein products. In our experience, Phase 0 microdose studies have not been fully embraced by the pharmaceutical industry. This notion is based on the number of Phase 0 studies that we have been involved in. Thus, we conducted at least 17 Phase 0 microdose studies in the Zero's (on average, two per year), but in the years beyond this, it was only 15 studies (1.4 per year); in these latter years, we did conduct a total of 23 studies which employed an intravenous (i.v.) microdose for absolute bioavailability (ABA) assessments (two per year on average), which are the most used and potentially informative type of clinical study using a microdose, albeit they are formally not microdose studies. In the current review, we summarize the past use of and experience with Phase 0 microdose designs in early clinical development, including intravenous 14C microdose ABA studies, and assess what is needed to increase the adoption of useful applications of Phase 0/microdose studies in the near future.

Absolute and Relative Bioavailability of Oral Solid Dosage Formulations of Deucravacitinib in Humans

Deucravacitinib is an oral, selective, allosteric inhibitor of tyrosine kinase 2, an intracellular signaling kinase involved in the pathogenesis of immune-mediated inflammatory diseases. The absolute and relative bioavailability (BA) were evaluated in phase 1, open-label studies in healthy adults to assess (1) the absolute BA of the deucravacitinib tablet formulation following single oral administration of a 12-mg tablet and an intravenous microdose infusion of 0.1-mg carbon-13 and nitrogen-15-labeled deucravacitinib ([13 C2 , 15 N3 ] deucravacitinib) solution in 8 subjects, and (2) the relative oral BA of deucravacitinib tablet and capsule formulations at the 3- and 12-mg dose levels in 20 subjects. The absolute oral availability of deucravacitinib in the tablet formulation was near complete at approximately 99%. The total clearance (254 mL/min) was low relative to hepatic blood flow, and volume of distribution (∼140 L) was greater than total body water, indicating extravascular distribution. Deucravacitinib systemic exposure (maximum plasma concentration, area under the plasma drug concentration curve from time zero to the time of the last quantifiable nonzero concentration, and area under the plasma drug concentration-time curve from time zero extrapolated to infinity) after administration of the tablet formulation were similar to the capsule at the tested 3- and 12-mg doses. In both studies, deucravacitinib was safe with no clinically relevant changes in laboratory values, electrocardiogram parameters, or vital signs.

Pharmacokinetic Properties of Dapagliflozin in Hemodialysis and Peritoneal Dialysis Patients

BACKGROUND

Sodium-glucose cotransporter 2 (SGLT2) inhibitors attenuate incident cardiovascular outcomes, irrespective of baseline GFR, in conservatively managed CKD. As this condition inexorably progresses to demanding KRT, drug withdrawal is supported by the current lack of evidence of safety of SGLT2 inhibitors in dialysis.

METHODS

This study was a prospective, single-center, open-label trial ( ClinicalTrials.gov identifier: NCT05343078 ) aimed at assessing the pharmacokinetic properties and safety of dapagliflozin in patients with kidney failure on regular dialysis regimens compared with those with type 2 diabetes and age- and sex-matched controls with normal kidney function. Peripheral blood samples were collected from both groups every 30 minutes for 4 hours and again after 48 hours after ingestion of dapagliflozin 10 mg, which occurred immediately before dialysis session initiation in the kidney failure group. This protocol occurred in drug-naïve patients and again after six daily doses of dapagliflozin to assess whether the drug had accumulated. The plasma and dialysate levels of dapagliflozin at each time point were determined by liquid chromatography and used to calculate pharmacokinetics parameters (peak concentration [C max ] and area under the plasma concentration-versus-time curve) for each participant.

RESULTS

Dapagliflozin C max was 117 and 97.6 ng/ml in the kidney failure and control groups, respectively, whereas the corresponding accumulation ratios were 26.7% and 9.5%. No serious adverse events were reported for either group. Dapagliflozin recovered from dialysate corresponded to 0.10% of the administered dose.

CONCLUSIONS

In patients with kidney failure on dialysis, dapagliflozin was well tolerated, was slightly dialyzable, and had nonaccumulating pharmacokinetic properties.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Pharmacokinetics and Dialyzability of Dapagliflozin in Dialysis Patients (DARE-ESKD 1), NCT05343078.

Impact of SGLT2 inhibitors on the kidney in people with type 2 diabetes and severely increased albuminuria

INTRODUCTION

Diabetes is the most common cause of end stage kidney disease. Therapies such as sodium-glucose co-transporter-2 inhibitors have been identified over the last decade as effective oral hypoglycemic agents that also confer additional cardio and kidney protection. Knowledge of their mechanism of action and impact on patients with diabetes and albuminuria is vital in galvanizing prescriber confidence and increasing clinical uptake.

AREAS COVERED

This manuscript discusses the pathophysiology of diabetic kidney disease, patho-physiological mechanisms for sodium-glucose co-transporter-2 inhibitors, and their impact on patients with Type 2 diabetes mellitus and albuminuric kidney disease.

EXPERT OPINION

Sodium-glucose co-transporter-2 inhibitors reduce albuminuria with consequent benefits on cardiovascular and kidney outcomes in patients with diabetes and severe albuminuria. Whilst they have been incorporated into guidelines, the uptake of these agents into clinical practice has been slow. Increasing the uptake of these agents into clinical practice is necessary to improve outcomes for the large number of patients with diabetic kidney disease globally.

Exenatide and Dapagliflozin Combination Enhances Sertoli Cell Secretion of Key Metabolites for Spermatogenesis

The incidence of metabolic diseases such as type 2 diabetes mellitus (DM) and obesity has been increasing dramatically. Both diseases are closely linked and new approaches for type 2 DM treatment aim to enable weight loss. A combined therapy of dapagliflozin and exenatide has been used against type 2 DM, influencing allbody glucose dynamics. Spermatogenesis is highly dependent on the metabolic cooperation established between Sertoli cells (SCs) and developing germ cells. To study the effects of dapagliflozin and exenatide on SC metabolism, mouse SCs were treated in the presence of sub-pharmacologic, pharmacologic, and supra-pharmacologic concentrations of dapagliflozin (50, 500, 5000 nM, respectively) and/or exenatide (2.5, 25, 250 pM, respectively). Cytotoxicity of these compounds was evaluated and the glycolytic profile, glycogen content assay, and lipid accumulation of SCs were determined. Dapagliflozin treatment decreased fat cellular deposits, demonstrating its anti-obesity properties at the cellular level. Polytherapy of exenatide plus dapagliflozin increased lactate production by SCs, which has been reported to improve sperm production and quality. Thus, the results herein suggest that the use of these two pharmacological agents can protect male fertility, while improving their glucose homeostasis and inducing weight loss.

A Phase 1 Study to Assess Mass Balance and Absolute Bioavailability of Zimlovisertib in Healthy Male Participants Using a 14 C-Microtracer Approach

Zimlovisertib (PF‐06650833) is a selective, reversible inhibitor of interleukin‐1 receptor‐associated kinase 4 (IRAK4) with anti‐inflammatory effects. This phase 1, open‐label, fixed‐sequence, two‐period, single‐dose study aimed to evaluate the mass balance and excretion rate of zimlovisertib in healthy male participants using a ¹⁴C‐microtracer approach. All six participants received 300 mg ¹⁴C‐zimlovisertib with lower radioactivity per mass unit orally in Period A, then unlabeled zimlovisertib 300 mg orally and ¹⁴C‐zimlovisertib 135 μg intravenously (IV) in Period B. Study objectives included extent and rate of excretion of ¹⁴C‐zimlovisertib, pharmacokinetics, and safety and tolerability of oral and IV zimlovisertib. Total radioactivity recovered in urine and feces was 82.4% ± 6.8% (urine 23.1% ± 12.3%, feces 59.3% ± 9.7%) in Period A. Zimlovisertib was absorbed rapidly following oral administration, with the fraction absorbed estimated to be 44%. Absolute oral bioavailability of the 300‐mg dose was 17.4% (90% confidence interval 14.1%, 21.5%) using the dose‐normalized area under the concentration–time curve from time 0 to infinity. There were no deaths, serious adverse events (AEs), severe AEs, discontinuations or dose reductions due to AEs, and no clinically significant laboratory abnormalities. These results demonstrate that zimlovisertib had low absolute oral bioavailability and low absorption (<50%).

Use of Physiologically Based Pharmacokinetic Modeling to Evaluate the Impact of Chronic Kidney Disease on CYP3A4-Mediated Metabolism of Saxagliptin

We characterized the impact of chronic kidney disease (CKD) on the cytochrome P450 (CYP) 3A4–mediated metabolism of saxagliptin to its metabolite, 5‐hydroxysaxagliptin, using a physiologically based pharmacokinetic (PBPK) model. A PBPK model of saxagliptin and its CYP3A4 metabolite, 5‐hydroxysaxagliptin, was constructed and validated for oral doses ranging from 5 to 100 mg. The observed ratios of area under the plasma concentration–time curve (AUC) and maximum plasma concentration (C_max) between healthy subjects and subjects with CKD were compared with those predicted using PBPK model simulations. Simulations were performed with virtual CKD populations having decreased CYP3A4 activity (ie, 64%‐75% of the healthy subjects’ CYP3A4 abundance) and preserved CYP3A4 activity (ie, 100% of the healthy subjects’ CYP3A4 abundance). We found that simulations using decreased CYP3A4 activity generally overpredicted the ratios of saxagliptin AUC and C_max in CKD compared with those using preserved CYP3A4 activity. Similarly, simulations using decreased CYP3A4 activity underpredicted the ratio of 5‐hydroxysaxagliptin AUC in moderate and severe CKD compared with simulations using preserved CYP3A4 activity. These findings suggest that decreased CYP3A4 activity in CKD underpredicts saxagliptin clearance compared with that observed clinically. Preserving CYP3A4 activity in CKD more closely estimates saxagliptin clearance and 5‐hydroxysaxagliptin exposure changes observed in vivo. Our findings suggest that there is no clinically meaningful impact of CKD on the metabolism of saxagliptin by CYP3A4. Since saxagliptin is not a highly sensitive substrate and validated probe for CYP3A4, this work represents a case study of a CYP3A4 substrate‐metabolite pair and is not a generalization for all CYP3A4 substrates.

Clinical Pharmacokinetics of Daprodustat: Results of an Absorption, Distribution, and Excretion Study With Intravenous Microtracer and Concomitant Oral Doses for Bioavailability Determination

Daprodustat, an oral hypoxia‐inducible factor prolyl hydroxylase inhibitor, is being investigated for treatment of anemia in chronic kidney disease. This phase 1, nonrandomized, 2‐period, crossover study in 6 healthy men characterized the absorption, distribution, and excretion of daprodustat when administered as oral and intravenous (IV) doses of unlabeled and radiolabeled daprodustat ([¹⁴C]‐GSK1278863). Tolerability and pharmacokinetic properties of daprodustat, and its 6 metabolites in the systemic circulation, were also evaluated. The mean recovery of radiolabeled daprodustat was ≈95% by day 5, with the majority in feces and minor renal elimination, indicating that daprodustat and metabolites are primarily eliminated via hepatobiliary and fecal routes. Approximately 40% of total circulating radioactivity in plasma following both IV and oral administration was daprodustat; thus, 60% was attributed to metabolites. It was estimated that ≈80% of daprodustat was absorbed across the gastrointestinal tract, and ≈18% cleared by hepatic extraction. Pharmacokinetics were essentially dose proportional, with moderate (≈66%) oral tablet bioavailability. Following IV administration, daprodustat plasma clearance (19.3 L/h) and volume of distribution (14.6 L) were low, suggesting low tissue distribution outside systemic circulation with likely low penetration into tissues. Daprodustat was generally well tolerated, with no deaths or serious or significant adverse events reported.

Sodium-Glucose Cotransporter 2 (SGLT-2) Inhibitors: Delving Into the Potential Benefits of Cardiorenal Protection Beyond the Treatment of Type-2 Diabetes Mellitus

Diabetes mellitus is a leading cause of morbidity and mortality and a significant risk factor for the early onset of chronic kidney disease and heart disease. Hyperglycemia and insulin resistance are key factors that play a role in the pathogenesis of type 2 diabetes. Renal glucose reabsorption is a critical component of glycemic regulation. Sodium-glucose cotransporter 2 (SGLT2) inhibitors, commonly known as gliflozins, lower blood sugar levels by inhibiting glucose absorption in the proximal tubule of the kidney. SGLT2 inhibitors are currently used primarily as antidiabetic medications; however, their advantages go well beyond just glycemic control. This article has reviewed the mechanisms behind cardiac and renal involvement in type 2 diabetes and their inseparable interconnections. This article has also discussed the pharmacokinetic and pharmacodynamic profile of different SGLT2 inhibitors available in the market. Finally, this review has provided a perspective on the outcome trials, which provide evidence supporting a potential benefit of SGLT2 inhibitors in reducing cardiovascular and renal risks and possible mechanisms that mediate the renal and cardiovascular protection conferred.

PBPK Modeling as a Tool for Predicting and Understanding Intestinal Metabolism of Uridine 5'-Diphospho-glucuronosyltransferase Substrates

Uridine 5′-diphospho-glucuronosyltransferases (UGTs) are expressed in the small intestines, but prediction of first-pass extraction from the related metabolism is not well studied. This work assesses physiologically based pharmacokinetic (PBPK) modeling as a tool for predicting intestinal metabolism due to UGTs in the human gastrointestinal tract. Available data for intestinal UGT expression levels and in vitro approaches that can be used to predict intestinal metabolism of UGT substrates are reviewed. Human PBPK models for UGT substrates with varying extents of UGT-mediated intestinal metabolism (lorazepam, oxazepam, naloxone, zidovudine, cabotegravir, raltegravir, and dolutegravir) have demonstrated utility for predicting the extent of intestinal metabolism. Drug–drug interactions (DDIs) of UGT1A1 substrates dolutegravir and raltegravir with UGT1A1 inhibitor atazanavir have been simulated, and the role of intestinal metabolism in these clinical DDIs examined. Utility of an in silico tool for predicting substrate specificity for UGTs is discussed. Improved in vitro tools to study metabolism for UGT compounds, such as coculture models for low clearance compounds and better understanding of optimal conditions for in vitro studies, may provide an opportunity for improved in vitro–in vivo extrapolation (IVIVE) and prospective predictions. PBPK modeling shows promise as a useful tool for predicting intestinal metabolism for UGT substrates.

"The pharmacological profile of SGLT2 inhibitors: Focus on mechanistic aspects and pharmacogenomics"

Diabetes, characterized by high glucose levels, has been listed to be one of the world's major causes of death. Around 1.6 million deaths are attributed to this disease each year. Persistent hyperglycemic conditions in diabetic patients affect various organs of the body leading to diabetic complications and worsen the disease condition. Current treatment strategies for diabetes include biguanides, sulfonylureas, alpha-glucosidase inhibitors, thiazolidinediones, insulin and its analogs, DPP-4(dipeptidyl peptidase-4) and GLP-1 (glucagon-like peptide) analogs. However, many side effects contributing to the devastation of the disease are associated with them. Sodium glucose co-transporter-2 (SGLT2) inhibition has been reported to be new insulin-independent approach to diabetes therapy. It blocks glucose uptake in the kidneys by inhibiting SGLT2 transporters, thereby promoting glycosuria. Dapagliflozin, empagliflozin and canagliflozin are the most widely used SGLT2 inhibitors. They are effective in controlling blood glucose and HbA1c levels with few side effects including hypoglycemia or weight gain which makes them preferable to other anti-diabetic drugs. However, treatment is found to be associated with inter-individual drug response to SGLT2 inhibitors and adverse drug reactions which are also affected by genetic variations. There have been very few pharmacogenetics trials of these drugs. This review discusses the various SGLT2 inhibitors, their pharmacokinetics, pharmacodynamics and genetic variation influencing the inter-individual drug response.

Model-Informed Pediatric Dose Selection for Dapagliflozin by Incorporating Developmental Changes

This analysis reports a quantitative modeling and simulation approach for oral dapagliflozin, a primarily uridine diphosphate-glucuronosyltransferase (UGT)-metabolized human sodium-glucose cotransporter 2 selective inhibitor. A mechanistic dapagliflozin physiologically based pharmacokinetic (PBPK) model was developed using in vitro metabolism and clinical pharmacokinetic (PK) data and verified for context of use (e.g., exposure predictions in pediatric subjects aged 1 month to 18 years). Dapagliflozin exposure is challenging to predict in pediatric populations owing to differences in UGT1A9 ontogeny maturation and paucity of clinical PK data in younger age groups. Based on the exposure-response relationship of dapagliflozin, twofold acceptance criteria were applied between model-predicted and observed drug exposures and PK parameters (area under the curve and maximum drug concentration) in various scenarios, including monotherapy in healthy adults (single/multiple dose), monotherapy in hepatically or renally impaired patients, and drug-drug interactions with UGT1A9 modulators, such as mefenamic acid and rifampin. The PBPK model captured the observed exposure within twofold of the observed monotherapy data in adults and adolescents and in special population. As a guide to determining dosing regimens in pediatric studies, the verified PBPK model, along with UGT enzyme ontogeny maturation understanding, was used for predictions of dapagliflozin monotherapy exposures in pediatric subjects aged 1 month to 18 years that best matched exposure in adult patients with a 10-mg single dose of dapagliflozin.

Physiologically-Based Pharmacokinetic Modeling of the Drug-Drug Interaction of the UGT Substrate Ertugliflozin Following Co-Administration with the UGT Inhibitor Mefenamic Acid

The sodium-glucose cotransporter 2 inhibitor ertugliflozin is metabolized by the uridine 5'-diphospho-glucuronosyltransferase (UGT) isozymes UGT1A9 and UGT2B4/2B7. This analysis evaluated the drug-drug interaction (DDI) following co-administration of ertugliflozin with the UGT inhibitor mefenamic acid (MFA) using physiologically-based pharmacokinetic (PBPK) modeling. The ertugliflozin modeling assumptions and parameters were verified using clinical data from single-dose and multiple-dose studies of ertugliflozin in healthy volunteers, and the PBPK fraction metabolized assignments were consistent with human absorption, distribution, metabolism, and excretion results. The model for MFA was developed using clinical data, and in vivo UGT inhibitory constant values were estimated using the results from a clinical DDI study with MFA and dapagliflozin, a UGT1A9 and UGT2B4/2B7 substrate in the same chemical class as ertugliflozin. Using the verified compound files, PBPK modeling predicted an ertugliflozin ratio of area under the plasma concentration-time curves (AUC_R ) of 1.51 when co-administered with MFA. ClinicalTrials.gov identifier: NCT00989079.

Evaluation of dapagliflozin in the treatment of heart failure

The European Society of Cardiology recently addressed the use of SGLT2 inhibitor use in the treatment of heart failure (HF). Dapagliflozin is a SGLT2 inhibitor recently approved by the US FDA for treatment of patients with HF with a reduced ejection fraction with a New York Heart Association classification of II-IV. Dapagliflozin significantly decreases the risk of worsening HF or death from cardiovascular cause compared with placebo and this risk does not differ based on the presence or absence of Type 2 diabetes. This paper aims to summarize the chemistry, pharmacodynamics and pharmacokinetics of dapagliflozin; and evaluates the clinical efficacy of dapagliflozin in the treatment of HF.

A Study of the Effect of Cyclosporine on Fevipiprant Pharmacokinetics and its Absolute Bioavailability Using an Intravenous Microdose Approach

This drug-drug interaction study determined the effect of cyclosporine, an inhibitor of organic anion transporting polypeptide (OATP) 1B3 and P-gp, on the pharmacokinetics (PK) of fevipiprant, an oral, highly selective, competitive antagonist of the prostaglandin D₂ receptor 2 and a substrate of the two transporters. The concomitant administration of an intravenous microdose of stable isotope-labeled fevipiprant provided the absolute bioavailability of fevipiprant as well as mechanistic insights into its PK and sensitivity to drug interactions. Liquid chromatography-mass spectrometry/mass spectrometry was used to measure plasma and urine concentrations. Geometric mean ratios [90% confidence interval (CI)] for oral fevipiprant with or without cyclosporine were 3.02 (2.38, 3.82) for C _max, 2.50 (2.17, 2.88) for AUC_last, and 2.35 (1.99, 2.77) for AUC_inf The geometric mean ratios (90% CI) for fevipiprant intravenous microdose with or without cyclosporine were 1.04 (0.86, 1.25) for C _max, 2.04 (1.83, 2.28) for AUC_last, and 1.95 (1.76, 2.16) for AUC_inf The absolute bioavailability for fevipiprant was approximately 0.3 to 0.4 in the absence and 0.5 in the presence of cyclosporine. The intravenous microdose allowed differentiation between systemic and presystemic effects of cyclosporine on fevipiprant, demonstrating a small (approximately 1.2-fold) presystemic effect of cyclosporine and a larger (approximately twofold) effect on systemic elimination of fevipiprant. Uptake by OATP1B3 appears to be the rate-limiting step in the hepatic elimination of fevipiprant, whereas P-gp does not have a relevant effect on oral absorption. SIGNIFICANCE STATEMENT: The drug interaction investigated here with cyclosporine, an inhibitor of several drug transporters, provides a refined quantitative understanding of the role of active transport processes in liver and intestine for the absorption and elimination of fevipiprant as well as the basis to assess the need for dose adjustment in the presence of transporter inhibitors. The applied intravenous microdose approach presents a strategy to maximize learnings from a trial, limit the number and duration of clinical trials, and enhance mechanistic drug-drug interaction understanding.

Application of Physiologically-Based Pharmacokinetic Modeling to Predict Gastric pH-Dependent Drug-Drug Interactions for Weak Base Drugs

Weak‐base drugs are susceptible to drug–drug interactions (DDIs) when coadministered with gastric acid–reducing agents (ARAs). We developed PBPK models to evaluate the potential of such pH‐dependent DDIs for four weak‐base drugs, i.e., tapentadol, darunavir, erlotinib, and saxagliptin. The physiologically‐based pharmacokinetic (PBPK) models of these drugs were first optimized using pharmacokinetic (PK) data following oral administration without ARAs, which were then verified with data from additional PK studies in the presence and absence of food. The models were subsequently used to predict the extent of DDIs with ARA coadministration. Sensitivity analysis was conducted to explore the impact of gastric pH on quantitative prediction of drug exposure in the presence of ARA. The results suggested that the PBPK models developed could adequately describe the lack of the effect of ARA on the PK of tapentadol, darunavir, and saxagliptin and could qualitatively predict the effect of ARA in reducing the absorption of erlotinib. Further studies involving more drugs with positive pH‐dependent DDIs are needed to confirm the findings and broaden our knowledge base to further improve the utilization of PBPK modeling to evaluate pH‐dependent DDI potential.

A Phase 1, Open-Label Study in Healthy Subjects to Evaluate the Absolute Bioavailability of AG-221 by a Microtracer Approach

Introduction

The purpose of this study was to evaluate the absolute bioavailability (BA) of AG-221 following a single oral dose of 100 mg AG-221 and an intravenous (IV) dose of ~ 100 μg AG-221 containing approximately 300 nCi of [¹⁴C]-AG-221.

Methods

This was a phase 1, open-label study. Six subjects who met all of the inclusion criteria and none of the exclusion criteria were enrolled in the study. After an overnight fast of at least 10 h, the subjects received an oral dose (coated tablet) of 100 mg of AG-221 at 0 h on dosing day. Four hours after the oral dose, the subjects received 100 μg AG-221 containing ~ 300 nCi of [¹⁴C]-AG-221 administered as an IV bolus. Blood samples were collected and analyzed for plasma concentrations of AG-221 and [¹⁴C]-AG-221 using a validated liquid chromatography with tandem mass spectrometry (LC–MS/MS) system and high-performance liquid chromatography (HPLC) fractionation followed by accelerator mass spectrometry analysis (AMS), respectively. Safety was evaluated throughout the study.

Results

The absolute BA after a 100-mg oral dose of AG-221 was measured as 57.2%. While the total clearance was 1.37 L/h, ~ 1/60 of the liver blood flow in a typical 70-kg human subject, the first-pass extraction was estimated to be less than 2%, assuming that the total clearance was entirely due to liver metabolism. Thus, the fraction of the AG-221 dose absorbed was at least 50%. AG-221 was safe and well tolerated when given under fasted conditions in a single 100-mg dose as a coated tablet with a microtracer [¹⁴C]-AG-221 solution, as few drug-related treatment-emergent adverse events (TEAEs) were reported. No clinically significant changes or findings were noted in the clinical laboratory evaluations, vital sign measurements, and electrocardiograms (ECGs) performed during this study.

Conclusions

In healthy subjects under fasting conditions, the absolute BA following oral administration of a 100-mg AG-221 tablet was 57.2%. AG-221 was safe and well tolerated in healthy male subjects when administered as a single 100-mg film-coated tablet plus 100 µg [¹⁴C]-AG-221 given intravenously.

Trial Registration

ClinicalTrials.gov identifier, NCT02443168.

Funding

Celgene Corporation.

Possibility of pharmacokinetic drug interaction between a DPP-4 inhibitor and a SGLT2 inhibitor

Type 2 diabetes mellitus is a multifactorial condition characterized by high level of sugar in the blood. To control hyperglycemia, combination therapy is recommended if monotherapy fails to achieve glycemic control. The combination of a dipeptidyl peptidase-4 (DPP-4) inhibitor and a sodium-glucose cotransporter type 2 (SGLT2) inhibitor is a promising option of the combination therapies in terms of safety as well as efficacy. Despite of the value of combination therapy of these two agents, the pharmacokinetic drug interactions between these two classes of agents have been evaluated in a few drugs. Thus, we reviewed the potential pharmacokinetic drug interaction based on the in vitro metabolism- and transporter-mediated drug interaction information as well as drug interaction studies in human, between a DPP-4 inhibitor and a SGLT2 inhibitor which are marketed in South Korea.

Sodium-glucose cotransporter 2 inhibitors for type 2 diabetes-cardiovascular and renal benefits in patients with chronic kidney disease

PURPOSE

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have important cardiovascular and renal benefits in adults with type 2 diabetes who have or are at high risk of cardiovascular and renal disease. These benefits are seen in patients with impaired renal function where the glucose-lowering effects are not observed. Here, we review the pharmacokinetics and pharmacology of SGLT2 inhibitors in relation to cardiovascular and renal outcomes in patients with chronic kidney disease (CKD).

METHODS

We searched PubMed and EMBASE for original research, meta-analyses and review articles relevant to the pharmacokinetics, and cardiac and renal outcomes of SGLT2 inhibitors published up until June 2019. Specialist society guidelines and publications were also consulted.

RESULTS

Renal impairment is currently a contraindication to SGLT2 inhibitor use largely due to limited anti-hyperglycaemic efficacy. However, in cardiovascular outcome trials, and a dedicated renal outcome trial, cardiovascular and renal benefits were seen in participants with CKD suggesting that mechanisms underlying the cardiovascular and renal benefits of SGLT2 inhibitors are likely largely independent of the glucose-lowering action of these agents.

CONCLUSIONS

Despite minimal glycaemic benefits in patients with type 2 diabetes and stage 3 CKD, the cardiovascular and renal benefits of these agents are preserved in this group of patients. Whether these agents have cardiovascular and renal benefits in patients with stage 4 CKD and patients with non-diabetic CKD needs further research.

Pharmacokinetic Interaction Study Between Saxagliptin and Omeprazole, Famotidine, or Magnesium and Aluminum Hydroxides Plus Simethicone in Healthy Subjects: An Open-Label Randomized Crossover Study

Saxagliptin is an orally administered, highly potent, and selective dipeptidyl peptidase-4 inhibitor for the management of type 2 diabetes mellitus. This study was conducted to determine the effect of magnesium and aluminum hydroxides plus simethicone, famotidine, and omeprazole on the pharmacokinetics of saxagliptin and its active metabolite, 5-hydroxy saxagliptin. This was an open-label, randomized, 5-treatment, 5-period, 3-way crossover study in 15 healthy subjects. Mean C_max of saxagliptin was 26% lower, but AUC was almost unchanged when saxagliptin was coadministered with Maalox Max. Mean C_max was 14% higher, but AUC was almost unchanged when saxagliptin was coadministered with famotidine. Changes in pharmacokinetics of 5-hydroxy saxagliptin generally paralleled the changes in saxagliptin. These pharmacokinetic changes were unlikely to be clinically meaningful. Coadministration of omeprazole did not affect saxagliptin C_max or AUC. Saxagliptin in combination with these medicines resulted in no unexpected safety or tolerability findings in these healthy subjects. No dose adjustment of saxagliptin or separation in the time of saxagliptin dosing is necessary with medicines that raise gastric pH when coadministered with saxagliptin.

A Quantitative Systems Pharmacology Kidney Model of Diabetes Associated Renal Hyperfiltration and the Effects of SGLT Inhibitors

The early stage of diabetes mellitus is characterized by increased glomerular filtration rate (GFR), known as hyperfiltration, which is believed to be one of the main causes leading to renal injury in diabetes. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have been shown to be able to reverse hyperfiltration in some patients. We developed a mechanistic computational model of the kidney that explains the interplay of hyperglycemia and hyperfiltration and integrates the pharmacokinetics/pharmacodynamics (PK/PD) of the SGLT2i dapagliflozin. Based on simulation results, we propose kidney growth as the necessary process for hyperfiltration progression. Further, the model indicates that renal SGLT1i could significantly improve hyperfiltration when added to SGTL2i. Integrated into a physiologically based PK/PD (PBPK/PD) Diabetes Platform, the model presents a powerful tool for aiding drug development, prediction of hyperfiltration risk, and allows the assessment of the outcomes of individualized treatments with SGLT1-inhibitors and SGLT2-inhibitors and their co-administration with insulin.

Metabolism and disposition of lesinurad, a uric acid reabsorption inhibitor, in humans

The objectives of this study were to determine the absolute bioavailability of lesinurad and to characterized its disposition in humans. The oral bioavailability assessment was performed using a clinical design of simultaneous dosing of a therapeutic oral dose of lesinurad with an intravenous infusion of [¹⁴C]lesinurad microdose. The bioavailability of lesinurad was determined to be 100%. The disposition of lesinurad in humans involves hepatic oxidation and renal elimination following administration of oral [¹⁴C]lesinurad dose. Metabolism of lesinurad occurred post-systemically with low circulating levels of metabolites <3% of total radioactivity as 74.2% of total radioactivity was attributed to lesinurad. In vitro metabolism studies identified CYP2C9 as the predominant isoform, and summation of metabolites indicated that it was responsible for ∼50% of metabolism.

Absolute Bioavailability of Osimertinib in Healthy Adults

Osimertinib is a third-generation, central nervous system-active, epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) selective for EGFR-TKI sensitizing and T790M resistance mutations. This phase 1, open-label study (NCT02491944) investigated absolute bioavailability and pharmacokinetics (PK) of oral and intravenous (IV) osimertinib. Ten healthy subjects (21-61 years) received a single oral 80-mg dose concomitantly with a 100 μg (containing 1 μCi) IV microtracer dose of [¹⁴ C]osimertinib. Oral and IV PK were determined simultaneously for osimertinib and its active metabolites, AZ5104 and AZ7550. High-performance liquid chromatography and accelerator mass spectrometry were used to characterize IV dose PK. Geometric mean absolute oral bioavailability of osimertinib was 69.8% (90% confidence interval, 66.7, 72.9). Oral osimertinib was slowly absorbed (median time to maximum plasma concentration [t_max ] 7.0 hours). Following t_max , plasma concentrations fell in an apparent monophasic manner. IV clearance and volume of distribution were 16.8 L/h and 1285 L, respectively. Arithmetic mean elimination half-life estimates were 59.7, 52.6, and 72.6 hours for osimertinib, AZ5104, and AZ7550, respectively (oral dosing), and 54.9, 68.4, and 99.7 hours for [¹⁴ C]osimertinib, [¹⁴ C]AZ5104, and [¹⁴ C]AZ7550, respectively (IV dosing). Oral osimertinib was well absorbed. Simultaneous IV and oral PK analysis proved useful for complete understanding of osimertinib PK and showed that the first-pass effect was minimal for osimertinib.

Novel Application of the Two-Period Microtracer Approach to Determine Absolute Oral Bioavailability and Fraction Absorbed of Ertugliflozin

Ertugliflozin, a sodium glucose cotransporter‐2 inhibitor, is approved in the United States for treatment of type 2 diabetes mellitus. A novel two‐period study design with ¹⁴C microtracer dosing in each period was used to determine absolute oral bioavailability (F) and fraction absorbed (F_a) of ertugliflozin. Eight healthy adult men received 100‐μg i.v. ¹⁴C‐ertugliflozin (400 nCi) dose 1 h after a 15‐mg oral unlabeled ertugliflozin dose (period 1), followed by 100 μg ¹⁴C‐ertugliflozin orally along with 15 mg oral unlabeled ertugliflozin (period 2). Unlabeled ertugliflozin plasma concentrations were determined using high‐performance liquid‐chromatography tandem mass spectrometry (HPLC‐MS/MS). ¹⁴C‐ertugliflozin plasma concentrations were determined using HPLC‐accelerator mass spectrometry (AMS) and ¹⁴C urine concentrations were determined using AMS. F ((area under the curve (AUC)_p.o./¹⁴C‐AUC_i.v.)*(¹⁴C‐Dose_i.v./Dose_p.o.)) and F_a ((¹⁴C_Total_Urine_p.o./¹⁴C_Total_Urine_i.v.)* (¹⁴C‐Dose_i.v./¹⁴C‐Dose_p.o.)) were estimated. Estimates of F and F_a were 105% and 111%, respectively. Oral absorption of ertugliflozin was complete under fasted conditions and F was ∼100%. Ertugliflozin was well tolerated.

Pharmacokinetic Characteristics and Clinical Efficacy of an SGLT2 Inhibitor Plus DPP-4 Inhibitor Combination Therapy in Type 2 Diabetes

Type 2 diabetes (T2D) generally requires a combination of several pharmacological approaches to control hyperglycaemia. Combining a sodium-glucose cotransporter type 2 inhibitor (SGLT2I, also known as gliflozin) and a dipeptidyl peptidase-4 inhibitor (DPP-4I, also known as gliptin) appears to be an attractive strategy because of complementary modes of action. This narrative review analyzes the pharmacokinetics and clinical efficacy of different combined therapies with an SGLT2I (canagliflozin, dapagliflozin, empagliflozin, ertugliflozin, ipragliflozin, luseogliflozin, tofogliflozin) and DPP-4I (linagliptin, saxagliptin, sitagliptin, teneligliptin). Drug-drug pharmacokinetic interaction studies do not show any significant changes in peak concentrations (C _max) and total exposure (area under the curve of plasma concentrations [AUC]) of either drug when they were administered together orally compared with corresponding values when each of them was absorbed alone. Two fixed-dose combinations (FDCs) are already available (dapagliflozin-saxagliptin, empagliflozin-linagliptin) and others are in development (ertugliflozin-sitagliptin). Preliminary results show bioequivalence of the two medications administered as FDC tablets when compared with coadministration of the individual tablets. Dual therapy is more potent than either monotherapy in patients treated with diet and exercise or already treated with metformin. SGLT2I and DPP-4I could be used as initial combination or in a stepwise approach. The additional glucose-lowering effect appears to be more marked when a gliflozin is added to a gliptin than when a gliptin is added to a gliflozin. Combining the two pharmacological options is safe and does not induce hypoglycaemia.

Antidiabetic "gliptins" affect biofilm formation by Streptococcus mutans

Streptococcus mutans, a dental caries causing odontopathogen, produces X-prolyl dipeptidyl peptidase (Sm-XPDAP, encoded by pepX), a serine protease known to have a nutritional role. Considering the potential of proteases as therapeutic targets in pathogens, this study was primarily aimed at investigating the role of Sm-XPDAP in contributing to virulence-related traits. Dipeptidyl peptidase (DPP IV), an XPDAP analogous enzyme found in mammalian tissues,is a well known therapeutic target in Type II diabetes. Based on the hypothesis that gliptins, commonly used as anti-human-DPP IV drugs, may affect bacterial growth upon inhibition of Sm-XPDAP, we have determined their ex vivo antimicrobial and anti-biofilm activity towards S. mutans. All three DPP IV drugs tested reduced biofilm formation as determined by crystal violet staining. To link the observed biofilm inhibition to the human-DPP IV analogue present in S. mutans UA159, a pepX isogenic mutant was generated. In addition to reduced biofilm formation, CLSM studies of the biofilm formed by the pepX isogenic mutant showed these were comparable to those formed in the presence of saxagliptin, suggesting a probable role of this enzyme in biofilm formation by S. mutans UA159. The effects of both pepX deletion and DPP IV drugs on the proteome were studied using LC-MS/MS. Overall, this study highlights the potential of Sm-XPDAP as a novel anti-biofilm target and suggests a template molecule to synthesize lead compounds effective against this enzyme.

Deuterium- and Tritium-Labelled Compounds: Applications in the Life Sciences

Hydrogen isotopes are unique tools for identifying and understanding biological and chemical processes. Hydrogen isotope labelling allows for the traceless and direct incorporation of an additional mass or radioactive tag into an organic molecule with almost no changes in its chemical structure, physical properties, or biological activity. Using deuterium-labelled isotopologues to study the unique mass-spectrometric patterns generated from mixtures of biologically relevant molecules drastically simplifies analysis. Such methods are now providing unprecedented levels of insight in a wide and continuously growing range of applications in the life sciences and beyond. Tritium (³ H), in particular, has seen an increase in utilization, especially in pharmaceutical drug discovery. The efforts and costs associated with the synthesis of labelled compounds are more than compensated for by the enhanced molecular sensitivity during analysis and the high reliability of the data obtained. In this Review, advances in the application of hydrogen isotopes in the life sciences are described.

Determination of the absolute oral bioavailability of niraparib by simultaneous administration of a 14C-microtracer and therapeutic dose in cancer patients

Introduction

Niraparib (Zejula™) is a poly(ADP-ribose) polymerase inhibitor recently approved by the US Food and Drug Administration for the maintenance treatment of patients with recurrent platinum-sensitive epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in a complete or partial response to platinum-based chemotherapy. The pivotal phase III clinical trial has shown improved progression-free survival in patients receiving niraparib compared with those receiving placebo.

Purpose

Since niraparib is administered orally, it is of interest to investigate the oral bioavailability (F_po) of this novel compound, which is the aim of this study.

Methods

Six patients received an oral therapeutic dose of 300 mg niraparib, followed by a 15-min intravenous infusion of 100 µg ¹⁴C-niraparib with a radioactivity of approximately 100 nCi. The niraparib therapeutic dose was measured in plasma using a validated liquid chromatography–tandem mass spectrometry method, whereas the total ¹⁴C-radioactivity and ¹⁴C-niraparib plasma levels were measured by accelerator mass spectrometry and a validated high performance liquid chromatography assay with AMS.

Results

The F_po of niraparib was determined to be 72.7% in humans.

Overcoming interference with the detection of a stable isotopically labeled microtracer in the evaluation of beclabuvir absolute bioavailability using a concomitant microtracer approach

The oral absolute bioavailability of beclabuvir in healthy subjects was determined using a microdose (100μg) of the stable isotopically labeled tracer via intravenous (IV) infusion started after oral dosing of beclabuvir (150mg). To simultaneously analyze the concentrations of the IV microtracer ([¹³C₆]beclabuvir) and beclabuvir in plasma samples, a liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) method was initially developed. Surprisingly beclabuvir significantly interfered with the IV microtracer detection when using the selected reaction monitoring (SRM) in the assay. An interfering component from the drug substance was observed using a high resolution mass spectrometer (HRMS). The mass-to-charge (m/z) of the interfering component was -32ppm different from the nominal value for the IV microtracer and thus could not be differentiated in the SRM assay by the unit mass resolution. To overcome this interference, we evaluated two approaches by either monitoring an alternative product ion using the SRM assay or isolating the interfering component using the parallel reaction monitoring (PRM) assay on the HRMS. This case study has demonstrated two practical approaches for overcoming interferences with the detection of stable isotopically labeled IV microtracers in the evaluation of absolute bioavailability, which provides users the flexibility in using either LC-MS/MS or HRMS to mitigate unpredicted interferences in the assay to support microtracer absolute bioavailability studies.

Pharmacokinetic drug evaluation of saxagliptin plus dapagliflozin for the treatment of type 2 diabetes

INTRODUCTION

Combining a dipeptidyl peptidase-4 inhibitor and a sodium-glucose cotransporter type 2 inhibitor is an attractive option to treat hyperglycaemia in type 2 diabetes. Areas covered: The saxagliptin plus dapagliflozin combination is carefully analysed, focusing on: 1) pharmacokinetic properties, 2) pharmacodynamics data, and 3) results of randomised controlled trials (dual combination versus either monotherapy, sequential therapy saxagliptin added to dapagliflozin or dapagliflozin added to saxagliptin). Expert opinion: Pharmacokinetic findings demonstrate the absence of drug-drug interaction and the bioequivalence of the FDC compared with separated tablets. Pharmacodynamic observations confirm a complementary mode of action of the two agents. Dual saxagliptin-dapagliflozin therapy is more potent than either monotherapy. It may be used as an initial combination, although this approach remains debatable and should probably be reserved in case of high glycated hemoglobin, or a stepwise strategy, according to a personalized approach. The developed saxagliptin-dapagliflozin FDC may simplify anti-hyperglycemic therapy and improve drug compliance.

An Accelerator Mass Spectrometry-Enabled Microtracer Study to Evaluate the First-Pass Effect on the Absorption of YH4808

¹⁴ C-labeled YH4808, a novel potassium-competitive acid blocker, was intravenously administered as a microtracer at 80 μg (11.8 kBq or 320 nCi) concomitantly with the nonradiolabeled oral drug at 200 mg to determine the absolute bioavailability and to assess the effect of pharmacogenomics on the oral absorption of YH4808. The absolute bioavailability was low and highly variable (mean, 10.1%; range, 2.3-19.3%), and M3 and M8, active metabolites of YH4808, were formed 22.6- and 38.5-fold higher after oral administration than intravenous administration, respectively. The product of the fraction of an oral YH4808 dose entering the gut wall and the fraction of YH4808 passing on to the portal circulation was larger in subjects carrying the variants of the CHST3, SLC15A1, and SULT1B1 genes. A combined LC+AMS is a useful tool to construct a rich and highly informative pharmacokinetic knowledge core in early clinical drug development at a reasonable cost.

DPP-4 inhibitor plus SGLT-2 inhibitor as combination therapy for type 2 diabetes: from rationale to clinical aspects

INTRODUCTION

Type 2 diabetes (T2D) is a complex disease with multiple defects, which generally require a combination of several pharmacological approaches to control hyperglycemia. Combining a dipeptidyl peptidase-4 inhibitor (DPP-4i) and a sodium-glucose cotransporter type 2 inhibitor (SGT2i) appears to be an attractive approach. Area covered: An extensive literature search was performed to analyze the pharmacokinetics, pharmacodynamics and clinical experience of different gliptin-gliflozin combinations. Expert opinion: There is a strong rationale for combining a DPP-4i and a SGLT2i in patients with T2D because the two drugs exert different and complementary glucose-lowering effects. Dual therapy (initial combination or stepwise approach) is more potent than either monotherapy in patients treated with diet and exercise or already treated with metformin. Combining the two pharmacological options is safe and does not induce hypoglycemia. The additional glucose-lowering effect is more marked when a gliflozin is added to a gliptin than when a gliptin is added to a gliflozin. Two fixed-dose combinations (FDCs) are already available (saxagliptin-dapagliflozin and linagliptin-empagliflozin) and others are in current development. Bioequivalence of the two compounds given as FDC tablets was demonstrated when compared with coadministration of the individual tablets. FDCs could simplify the anti-hyperglycaemic therapy and improve drug compliance.

Adding value through accelerator mass spectrometry-enabled first in human studies

Accelerator mass spectrometry (AMS) is an ultra-sensitive technique for the analysis of radiocarbon. It is applicable to bioanalysis of any ¹⁴ C-labelled analyte and any sample type. The increasing body of data generated using LC+AMS indicates that the methodology is robust and reliable, and capable of meeting the same validation criteria as conventional bioanalytical techniques. Because it is a tracer technique, AMS is capable of discriminating between an administered radiolabelled dose and endogenous compound or non-radiolabelled compound administered separately. This paper discusses how it can be used to enhance the design of first in human (FIH) clinical studies and generate significant additional data, including: fundamental pharmacokinetics (CL and V), absolute bioavailability, mass balance, routes and rates of excretion, metabolic fate (including first-pass metabolism, identification of biliary metabolites and quantitative data to address metabolite safety testing issues), and tissue disposition of parent compound and metabolites. Because the ¹⁴ C-labelled microtracer dose is administered at the same time as a pharmacologically relevant non-radiolabelled dose, there is no concern about dose-linearity. However the mass of the microtracer dose itself is negligible and therefore does not affect the outcome of the FIH study. The addition of microtracer doses to a FIH study typically requires little additional expense, apart from the AMS analytics, making the approach cost-effective. It can also save significant time, compared to conventional approaches, and, by providing reliable human in vivo data as early as possible, prevent unnecessary expenditure later in drug development.

Pharmacokinetics and pharmacodynamics of dapagliflozin in children and adolescents with type 2 diabetes mellitus

AIMS

To evaluate the pharmacokinetic (PK)/pharmacodynamic (PD) and safety profile of dapagliflozin in paediatric patients aged 10-17 years with type 2 diabetes mellitus (T2DM).

METHODS

Patients were randomized to a single oral dose of dapagliflozin 2.5, 5 or 10 mg. The PK characteristics for individual patients were derived by non-compartmental methods. Urinary glucose excretion (UGE), fasting plasma glucose (FPG) and ease of swallowing were also evaluated.

RESULTS

A total of 24 patients with a mean (range) body weight of 99.7 (61.5-169.5) kg received dapagliflozin. Dapagliflozin was rapidly absorbed after oral administration (median time to maximum plasma concentration ∼1.5 h) and systemic exposures to dapagliflozin and its 3-O-glucuronide metabolite appeared dose-proportional. The mean 24-h UGE increased in a dose-related manner (52.8, 62.4 and 89.0 g for the 2.5, 5 and 10 mg groups, respectively). Mean FPG concentrations were lower for all dose groups on day 2 (6.9, 6.2 and 6.8 mmol/l for 2.5, 5 and 10 mg groups, respectively) than they were predose on day 1 (9.5, 8.5 and 8.2 mmol/l for 2.5, 5 and 10 mg groups, respectively). Six patients (25%) experienced ≥1 adverse event (AE), however, there was no dose-related pattern. All AEs occurred only once and most were mild in intensity. Nearly all patients (n = 23; 95.8%) reported easy swallowing of the dapagliflozin tablets.

CONCLUSIONS

Dapagliflozin was well tolerated in this paediatric population, with no significant safety findings. PK/PD characteristics were similar to those observed in adults with T2DM, thereby supporting the hypothesis that the same dapagliflozin dosage as that used in adults can be evaluated in future phase III paediatric studies.

Comparison of the exposure-response relationship of dapagliflozin in adult and paediatric patients with type 2 diabetes mellitus

AIMS

To quantitatively compare the exposure-response relationship of dapagliflozin in adult and paediatric patients with type 2 diabetes mellitus (T2DM) and to assess the potential impact of covariate effects.

METHODS

Data from three clinical studies of single-dose (2.5, 5 and 10 mg), orally administered dapagliflozin in adult (NCT00162305, NCT00538174) and paediatric (NCT01525238) patients with T2DM were analysed to examine the relationship between dapagliflozin exposure (area under concentration-time curve) and response [24-h urinary glucose excretion (UGE)] using a sigmoidal maximum effect model. Baseline fasting plasma glucose (FPG), estimated glomerular filtration rate (eGFR), baseline 24-h UGE, sex and race were evaluated as covariates.

RESULTS

Data from 63 predominantly white or Asian (92.4%) adult and 20 paediatric (45.8% white; 45.8% black) patients were included. The model appeared robust, with predictions fitting well with observed data. Baseline eGFR, FPG and sex were significant covariates in both populations; race was a significant covariate in the paediatric population only. Model-predicted UGE response was higher in paediatric (47.4, 67.5 and 85.9 g/24 h for 2.5, 5 and 10 mg) than in adult (31.2, 43.5 and 54.3 g/24 h for 2.5, 5 and 10 mg) patients, which may be associated with the higher eGFR values in paediatric patients.

CONCLUSIONS

After a single oral dose of dapagliflozin, adult and paediatric patients with T2DM had similar exposure-response relationships after accounting for significant covariates. These results support the planned dosage strategy for a phase III dapagliflozin safety and efficacy study in paediatric patients with T2DM, for whom treatment options are currently limited.

Absolute bioavailability of evacetrapib in healthy subjects determined by simultaneous administration of oral evacetrapib and intravenous [(13) C8 ]-evacetrapib as a tracer

This open-label, single-period study in healthy subjects estimated evacetrapib absolute bioavailability following simultaneous administration of a 130-mg evacetrapib oral dose and 4-h intravenous (IV) infusion of 175 µg [(13) C8 ]-evacetrapib as a tracer. Plasma samples collected through 168 h were analyzed for evacetrapib and [(13) C8 ]-evacetrapib using high-performance liquid chromatography/tandem mass spectrometry. Pharmacokinetic parameter estimates following oral and IV doses, including area under the concentration-time curve (AUC) from zero to infinity (AUC[0-∞]) and to the last measureable concentration (AUC[0-tlast ]), were calculated. Bioavailability was calculated as the ratio of least-squares geometric mean of dose-normalized AUC (oral : IV) and corresponding 90% confidence interval (CI). Bioavailability of evacetrapib was 44.8% (90% CI: 42.2-47.6%) for AUC(0-∞) and 44.3% (90% CI: 41.8-46.9%) for AUC(0-tlast ). Evacetrapib was well tolerated with no reports of clinically significant safety assessment findings. This is among the first studies to estimate absolute bioavailability using simultaneous administration of an unlabeled oral dose with a (13) C-labeled IV microdose tracer at about 1/1000(th) the oral dose, with measurement in the pg/mL range. This approach is beneficial for poorly soluble drugs, does not require additional toxicology studies, does not change oral dose pharmacokinetics, and ultimately gives researchers another tool to evaluate absolute bioavailability.

Stable isotope-labelled intravenous microdose for absolute bioavailability and effect of grapefruit juice on ibrutinib in healthy adults

AIMS

Ibrutinib, an inhibitor of Bruton's tyrosine kinase, is used in the treatment of mantle cell lymphoma or chronic lymphocytic leukaemia. Ibrutinib undergoes extensive rapid oxidative metabolism mediated by cytochrome P450 3A both at the level of first pass and clearance, which might result in low oral bioavailability. The present study was designed to investigate the absolute bioavailability (F) of ibrutinib in the fasting and fed state and assess the effect of grapefruit juice (GFJ) on the systemic exposure of ibrutinib in order to determine the fraction escaping the gut (Fg ) and the fraction escaping hepatic extraction (Fh ) in the fed state.

METHODS

All participants received treatment A [560 mg oral ibrutinib, under fasting conditions], B (560 mg PO ibrutinib, fed, administered after drinking glucose drink) and C (140 mg oral ibrutinib, fed, with intake of GFJ before dosing). A single intravenous (i.v.) dose of 100 μg (13) C6 -ibrutinib was administered 2 h after each oral dose.

RESULTS

The estimated 'F' for treatments A, B and C was 3.9%, 8.4% and 15.9%, respectively. Fg and Fh in the fed state were 47.0% and 15.9%, respectively. Adverse events were mild to moderate in severity (Grade 1-2) and resolved without sequelae by the end of the study.

CONCLUSION

The absolute oral bioavailability of ibrutinib was low, ranging from 3.9% in the fasting state to 8.4% when administered 30 min before a standard breakfast without GFJ and 15.9% with GFJ. Ibrutinib was well tolerated following a single oral and i.v. dose, under both fasted and fed conditions and regardless of GFJ intake status.

Optimization of human dose prediction by using quantitative and translational pharmacology in drug discovery

In this perspective article, we explain how quantitative and translational pharmacology, when well-implemented, is believed to lead to improved clinical candidates and drug targets that are differentiated from current treatment options. Quantitative and translational pharmacology aims to build and continuously improve the quantitative relationship between drug exposure, target engagement, efficacy, safety and its interspecies relationship at every phase of drug discovery. Drug hunters should consider and apply these concepts to develop compounds with a higher probability of interrogating the clinical biological hypothesis. We offer different approaches to set an initial effective concentration or pharmacokinetic-pharmacodynamic target in man and to predict human pharmacokinetics that determine together the predicted human dose and dose schedule. All concepts are illustrated with ample literature examples.

The application of human phase 0 microdosing trials: A systematic review and perspectives

A decreasing number of new therapeutic drugs reaching the clinic has led to the publication of regulatory guidelines on human microdosing trials by the European Medicines Agency in 2004 and the US Food and Drug Administration in 2006. Microdosing trials are defined by the administration of 1/100th of the therapeutic dose and designed to investigate basic drug properties. This review investigates the current application of phase 0 trials in medical research. Thirty-three studies found in PubMed and EMBASE were systematically reviewed for aim and analytical method. Pharmacokinetic studies have been a major focus of phase 0 trials, but drug distribution, drug-drug interactions, imaging and pharmacogenomics have also been investigated. Common analytical methods were tandem mass liquid chromatography, accelerator mass spectrometry and positron emission tomography. New ongoing trials are investigating the pharmacodynamics and chemoresistance of marketed drugs, suggesting that the application of phase 0 trials is still evolving.

The clinical application of linagliptin in Asians

Asia has a growing diabetic population. Linagliptin, a member of dipeptidyl peptidase-4 inhibitor class, is unique in its nonlinear pharmacokinetics with the characteristics of rapid attainment of steady state, little accumulation, predominantly nonrenal route of elimination, prolonged terminal half-life, and sustained inhibition of dipeptidyl peptidase-4 enzyme. No clinically relevant difference in pharmacokinetics was observed between Asians and non-Asians. The management of type 2 diabetes is increasingly challenging with the progression of disease, especially with the requirements of minimal hypoglycemia, weight gain, fluid retention, and other adverse effects. Linagliptin was efficacious and well-tolerated in Asian type 2 diabetes patients with or without renal or hepatic dysfunctions, comparable to that in Caucasians. This review will focus on the usage of linagliptin in clinical studies in Asians.

Observational infant exploratory [(14)C]-paracetamol pharmacokinetic microdose/therapeutic dose study with accelerator mass spectrometry bioanalysis

AIMS

The aims of the study were to compare [(14)C]-paracetamol ([(14)C]-PARA) paediatric pharmacokinetics (PK) after administration mixed in a therapeutic dose or an isolated microdose and to develop further and validate accelerator mass spectrometry (AMS) bioanalysis in the 0-2 year old age group.

METHODS

[(14)C]-PARA concentrations in 10-15 µl plasma samples were measured after enteral or i.v. administration of a single [(14)C]-PARA microdose or mixed in with therapeutic dose in infants receiving PARA as part of their therapeutic regimen.

RESULTS

Thirty-four infants were included in the PARA PK analysis for this study: oral microdose (n = 4), i.v. microdose (n = 6), oral therapeutic (n = 6) and i.v. therapeutic (n = 18). The respective mean clearance (CL) values (SDs in parentheses) for these dosed groups were 1.46 (1.00) l h(-1), 1.76 (1.07) l h(-1), 2.93 (2.08) l h(-1) and 2.72 (3.10) l h(-1), t(1/2) values 2.65 h, 2.55 h, 8.36 h and 7.16 h and dose normalized AUC(0-t) (mg l(-1) h) values were 0.90 (0.43), 0.84 (0.57), 0.7 (0.79) and 0.54 (0.26).

CONCLUSIONS

All necessary ethical, scientific, clinical and regulatory procedures were put in place to conduct PK studies using enteral and systemic microdosing in two European centres. The pharmacokinetics of a therapeutic dose (mg kg(-1)) and a microdose (ng kg(-1)) in babies between 35 to 127 weeks post-menstrual age. [(14)C]-PARA pharmacokinetic parameters were within a two-fold range after a therapeutic dose or a microdose. Exploratory studies using doses significantly less than therapeutic doses may offer ethical and safety advantages with increased bionalytical sensitivity in selected exploratory paediatric pharmacokinetic studies.

Concomitant oral and intravenous pharmacokinetics of trametinib, a MEK inhibitor, in subjects with solid tumours

AIMS

The aim of this phase 1, single centre, open label study in four patients with solid tumours was to determine the absolute bioavailability of a 2 mg oral dose of trametinib. Trametinib is an orally bioavailable, reversible and selective allosteric inhibitor of MEK1 and MEK2 activation and kinase activity.

METHODS

A microtracer study approach, in which a 5 μg radiolabelled i.v. microdose of trametinib was given concomitantly with an unlabelled 2 mg oral tablet formulation, was used to recover i.v. and oral pharmacokinetic parameters, simultaneously.

RESULTS

The least-squares mean (90% confidence interval) absolute bioavailability of trametinib (2 mg tablet) was 72.3% (50.0%, 104.6%). Median tmax after oral administration was 1.5 h and the geometric mean terminal half-life was 11 days. The geometric mean clearance and volume of distribution after i.v. administration were 3.21 l h(-1) and 976 l, respectively, resulting in a terminal elimination half-life of 11 days.

CONCLUSIONS

Trametinib absolute bioavailability was moderate to high, whereas first pass metabolism was low.