Drug-Drug Interaction of Letermovir and Atorvastatin in Healthy Participants

Letermovir (MK-8228/AIC246) is a cytomegalovirus (CMV) DNA terminase complex inhibitor for CMV prophylaxis in adult patients undergoing hematopoietic stem cell transplant. It is cytochrome P450 (CYP) 3A inhibitor and inhibits organic anion transporting polypeptide 1B1/3 and breast cancer resistance protein transporters. Atorvastatin (ATV), a commonly used treatment for hypercholesterolemia, is a substrate of organic anion transporting polypeptide 1B1, potentially breast cancer resistance protein, and CYP3A. As letermovir may be coadministered with ATV, the effect of multiple-dose letermovir 480 mg once daily on the pharmacokinetics of single-dose ATV 20 mg and its metabolites (ortho-hydroxyatorvastatin [o-OH-ATV] and para-hydroxyatorvastatin [p-OH-ATV]) was evaluated in an open-label trial in healthy female adults (N = 14). ATV area under the plasma concentration-time curve from time 0 to infinity and maximum plasma concentration (C_max ) increased ≈3-fold with letermovir coadministration. The time to ATV C_max also increased, while apparent clearance decreased. The exposures of o-OH-ATV and p-OH-ATV were comparable in the presence versus absence of letermovir; however, o-OH-ATV C_max decreased by 60% with coadministration, while p-OH-ATV C_max was similar. Due to the increase in ATV exposure with letermovir coadministration, statin-associated adverse events such as myopathy should be closely monitored following coadministration. The dose of ATV should not exceed 20 mg daily when coadministered with letermovir.

Exposure-Response Analyses of Letermovir Following Oral and Intravenous Administration in Allogeneic Hematopoietic Cell Transplantation Recipients

The cytomegalovirus (CMV) viral terminase inhibitor letermovir is approved for prophylaxis of CMV infection and disease in adult CMV-seropositive allogeneic hematopoietic stem cell transplantation recipients. In a phase III trial (NCT02137772), letermovir significantly reduced clinically significant CMV infection (CS-CMVi) rate vs. placebo through Week 24 (primary end point) and Week 14 (secondary end point) post transplantation. Here, exposure-response relationships were investigated using efficacy and selected safety end points from the phase III trial to inform the proposed clinical dose. Post hoc exposure estimates were derived from a population pharmacokinetic model. No significant exposure dependencies were found for CS-CMVi through Week 24 or Week 14 among letermovir-treated participants. Evaluated covariates had no impact on exposure-efficacy relationships and letermovir plasma exposure did not affect time of CS-CMVi onset. There was no dependence between adverse event incidence and letermovir exposure. These results support current dosing recommendations in several countries and regions, including the United States and European Union.

A Disease Progression Model to Quantify the Nonmotor Symptoms of Parkinson's Disease in Participants With Leucine-Rich Repeat Kinase 2 Mutation

Leucine-rich repeat kinase 2 (LRRK2) inhibitors are currently in clinical development as interventions to slow progression of Parkinson's disease (PD). Understanding the rate of progression in PD as measured by both motor and nonmotor features is particularly important in assessing the potential therapeutic effect of LRRK2 inhibitors in clinical development. Using standardized data from the Critical Path for Parkinson's Unified Clinical Database, we quantified the rate of progression of the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part I (nonmotor aspects of experiences of daily living) in 158 participants with PD who were carriers and 598 participants with PD who were noncarriers of at least one of three different LRRK2 gene mutations (G2019S, R1441C/G, or R1628P). Age and disease duration were found to predict baseline disease severity, while presence of at least one of these three LRRK2 mutations was a predictor of the rate of MDS-UPDRS Part I progression. The estimated progression rate in MDS-UPDRS Part I was 0.648 (95% confidence interval: 0.544, 0.739) points per year in noncarriers of a LRRK2 mutation and 0.259 (95% confidence interval: 0.217, 0.295) points per year in carriers of a LRRK2 mutation. This analysis demonstrates that the rate of progression based on MDS-UPDRS Part I is ~ 60% lower in carriers as compared with noncarriers of LRRK2 gene mutations.

Quantitative systems pharmacology in neuroscience: Novel methodologies and technologies

The development and application of quantitative systems pharmacology models in neuroscience have been modest relative to other fields, such as oncology and immunology, which may reflect the complexity of the brain. Technological and methodological advancements have enhanced the quantitative understanding of brain physiology and pathophysiology and the effects of pharmacological interventions. To maximize the knowledge gained from these novel data types, pharmacometrics modelers may need to expand their toolbox to include additional mathematical and statistical frameworks. A session was held at the 10th annual American Conference on Pharmacometrics (ACoP10) to highlight several recent advancements in quantitative and systems neuroscience. In this mini‐review, we provide a brief overview of technological and methodological advancements in the neuroscience therapeutic area that were discussed during the session and how these can be leveraged with quantitative systems pharmacology modeling to enhance our understanding of neurological diseases. Microphysiological systems using human induced pluripotent stem cells (IPSCs), digital biomarkers, and large‐scale imaging offer more clinically relevant experimental datasets, enhanced granularity, and a plethora of data to potentially improve the preclinical‐to‐clinical translation of therapeutics. Network neuroscience methodologies combined with quantitative systems models of neurodegenerative disease could help bridge the gap between cellular and molecular alterations and clinical end points through the integration of information on neural connectomics. Additional topics, such as the neuroimmune system, microbiome, single‐cell transcriptomic technologies, and digital device biomarkers, are discussed in brief.

Population pharmacokinetics of letermovir following oral and intravenous administration in healthy participants and allogeneic hematopoietic cell transplantation recipients

Letermovir is indicated for prophylaxis of cytomegalovirus infection and disease in allogeneic hematopoietic stem cell transplant (HSCT) recipients. Two‐stage population pharmacokinetic (PK) modeling of letermovir was conducted to support dose rationale and evaluate the impact of intrinsic/extrinsic factors. Data from healthy phase I study participants over a wide dose range were modeled to evaluate the effects of selected intrinsic factors, including pharmacogenomics; next, phase III HSCT‐recipient data at steady‐state following clinical doses were modeled. The model in HSCT recipients adequately described letermovir PK following both oral or i.v. administration, and was consistent with the healthy participant model at steady‐state clinical doses. Intrinsic factor effects were not clinically meaningful. These staged analyses indicate that letermovir PK in HSCT recipients and healthy participants differ only with respect to bioavailability and absorption rate. The HSCT recipient model was suitable for predicting exposure for exposure–response analysis supporting final dose selection.

Performance of longitudinal item response theory models in shortened or partial assessments

This work evaluates the performance of longitudinal item response (IR) theory models in shortened assessments using an existing model for part II and III of the MDS-UPDRS score. Based on the item information content, the assessment was reduced by removal of items in multiple increments and the models’ ability to recover the item characteristics of the remaining items at each level was evaluated. This evaluation was done for both simulated and real data. The metric of comparison in both cases was the item information function. For real data, the impact of shortening on the estimated disease progression and drug effect was also studied. In the simulated data setting, the item characteristics did not differ between the full and the shortened assessments down to the lowest level of information remaining; indicating a considerable independence between items. In contrast when reducing the assessment in a real data setting, a substantial change in item information was observed for some of the items. Disease progression and drug effect estimates also decreased in the reduced assessments. These changes indicate a shift in the measured construct of the shortened assessment and warrant caution when comparing results from a partial assessment with results from the full assessment.

Development of a Disease Progression Model for Leucine-Rich Repeat Kinase 2 in Parkinson's Disease to Inform Clinical Trial Designs

A quantitative assessment of Parkinson's disease (PD) progression is critical for optimizing clinical trials design. Disease progression model was developed using pooled data from the Progression Marker Initiative study and the Incidence of Cognitive Impairment in Cohorts with Longitudinal Evaluation in Parkinson's Disease study. Age, gender, concomitant medication, and study arms were predictors of baseline. A mutation in the leucine-rich repeat kinase 2 (LRRK2) encoding gene was associated with the disease progression rate. The progression rate in subjects with PD who carried LRRK2 mutation was slightly slower (~0.170 points/month) than that in PD subjects without the mutation (~0.222 points/month). For a nonenriched placebo-controlled clinical trial, approximately 70 subjects/arm would be required to detect a drug effect of 50% reduction in the progression rate with 80% probability, whereas 85, 93, and 100 subjects/arm would be required for an enriched clinical trial with 30%, 50%, and 70% subjects with LRRK2 mutations, respectively.

Challenges in Alzheimer's Disease Drug Discovery and Development: The Role of Modeling, Simulation, and Open Data

Alzheimer's disease (AD) is the leading cause of dementia worldwide. With 35 million people over 60 years of age with dementia, there is an urgent need to develop new treatments for AD. To streamline this process, it is imperative to apply insights and learnings from past failures to future drug development programs. In the present work, we focus on how modeling and simulation tools can leverage open data to address drug development challenges in AD.

Pharmacokinetic Drug-Drug Interactions Between Letermovir and the Immunosuppressants Cyclosporine, Tacrolimus, Sirolimus, and Mycophenolate Mofetil

Letermovir (AIC246, MK-8228) is a human cytomegalovirus terminase inhibitor indicated for the prophylaxis of cytomegalovirus infection and disease in allogeneic hematopoietic stem cell transplant recipients that is also being investigated for use in other transplant settings. Many transplant patients receive immunosuppressant drugs, of which several have narrow therapeutic ranges. There is a potential for the coadministration of letermovir with these agents, and any potential effect on their pharmacokinetics (PK) must be understood. Five phase 1 trials were conducted in 73 healthy female participants to evaluate the effect of letermovir on the PK of cyclosporine, tacrolimus, sirolimus, and mycophenolic acid (active metabolite of mycophenolate mofetil [MMF]), as well as the effect of cyclosporine and MMF on letermovir PK. Safety and tolerability were also assessed. Coadministration of letermovir with cyclosporine, tacrolimus, and sirolimus resulted in 1.7-, 2.4-, and 3.4-fold increases in area under the plasma concentration-time curve and 1.1-, 1.6-, and 2.8-fold increases in maximum plasma concentration, respectively, of the immunosuppressants. Coadministration of letermovir and MMF had no meaningful effect on the PK of mycophenolic acid. Coadministration with cyclosporine increased letermovir area under the plasma concentration-time curve by 2.1-fold and maximum plasma concentration by 1.5-fold, while coadministration with MMF did not meaningfully affect the PK of letermovir. Given the increased exposures of cyclosporine, tacrolimus, and sirolimus, frequent monitoring of concentrations should be performed during administration and at discontinuation of letermovir, with dose adjustment as needed. These data support the reduction in clinical dosage of letermovir (to 240 mg) upon coadministration with cyclosporine.

Molecular Neuroimaging of the Dopamine Transporter as a Patient Enrichment Biomarker for Clinical Trials for Early Parkinson's Disease

The Critical Path for Parkinson's (CPP) Imaging Biomarker and Modeling and Simulation working groups aimed to achieve qualification opinion by the European Medicines Agency (EMA) Committee for Medical Products for Human Use (CHMP) for the use of baseline dopamine transporter neuroimaging for patient selection in early Parkinson's disease clinical trials. This paper describes the regulatory science strategy to achieve this goal. CPP is an international consortium of three Parkinson's charities and nine pharmaceutical partners, coordinated by the Critical Path Institute.

Dopamine Transporter Neuroimaging as an Enrichment Biomarker in Early Parkinson's Disease Clinical Trials: A Disease Progression Modeling Analysis

Given the recognition that disease‐modifying therapies should focus on earlier Parkinson's disease stages, trial enrollment based purely on clinical criteria poses significant challenges. The goal herein was to determine the utility of dopamine transporter neuroimaging as an enrichment biomarker in early motor Parkinson's disease clinical trials. Patient‐level longitudinal data of 672 subjects with early‐stage Parkinson's disease in the Parkinson's Progression Markers Initiative (PPMI) observational study and the Parkinson Research Examination of CEP‐1347 Trial (PRECEPT) clinical trial were utilized in a linear mixed‐effects model analysis. The rate of worsening in the motor scores between subjects with or without a scan without evidence of dopamine transporter deficit was different both statistically and clinically. The average difference in the change from baseline of motor scores at 24 months between biomarker statuses was –3.16 (90% confidence interval [CI] = –0.96 to –5.42) points. Dopamine transporter imaging could identify subjects with a steeper worsening of the motor scores, allowing trial enrichment and 24% reduction of sample size.

The effect of empagliflozin on muscle sympathetic nerve activity in patients with type II diabetes mellitus

Inhibition of sodium glucose cotransporter 2 with empagliflozin results in caloric loss by increasing urinary glucose excretion and has a mild diuretic effect. Diuretic effects are usually associated with reflex-mediated increases in sympathetic tone, whereas caloric loss is associated with decreased sympathetic tone. In an open-label trial, muscle sympathetic nerve activity (MSNA) (burst frequency, burst incidence, and total MSNA) was assessed using microneurography performed off-treatment and on day 4 of treatment with empagliflozin 25 mg once daily in 22 metformin-treated patients with type II diabetes (mean [range] age 54 [40-65] years). Systolic and diastolic blood pressure (BP), heart rate, urine volume, and body weight were assessed before and on day 4 (BP, heart rate), day 5 (urine volume), or day 6 (body weight) of treatment with empagliflozin. After 4 days of treatment with empagliflozin, no significant changes in MSNA were apparent despite a numerical increase in urine volume, numerical reductions in BP, and significant weight loss. There were no clinically relevant changes in heart rate. Empagliflozin is not associated with clinically relevant reflex-mediated sympathetic activation in contrast to increases observed with diuretics in other studies. Our study suggests a novel mechanism through which sodium glucose cotransporter 2 inhibition affects human autonomic cardiovascular regulation.

Population Pharmacokinetics and Exposure-Response (Efficacy and Safety/Tolerability) of Empagliflozin in Patients with Type 2 Diabetes

INTRODUCTION

The aim of the analysis was to characterize the population pharmacokinetics (PKs) and exposure-response (E-R) for efficacy (fasting plasma glucose, glycated hemoglobin) and safety/tolerability [hypoglycemia, genital infections, urinary tract infection (UTI), and volume depletion] of the sodium glucose cotransporter 2 inhibitor, empagliflozin, in patients with type 2 diabetes mellitus. This study extends the findings of previous analyses which described the PK and pharmacodynamics (PD) using early clinical studies of up to 12 weeks in duration.

METHODS

Population pharmacokinetic and E-R models were developed based on two Phase I, four Phase II, and four Phase III studies.

RESULTS

Variability in empagliflozin exposure was primarily affected by estimated glomerular filtration rate (eGFR) (less than twofold increase in exposure in patients with severe renal impairment). Consistent with its mode of action, the efficacy of empagliflozin was increased with elevated baseline plasma glucose levels and attenuated with decreasing renal function, but was still maintained to nearly half the maximal effect with eGFR as low as 30 mL/min/1.73 m(2). All other investigated covariates, including sex, body mass index, race, and age did not alter the PK or efficacy of empagliflozin to a clinically relevant extent. Compared with placebo, empagliflozin administration was associated with an exposure-independent increase in the incidence of genital infections and no significant change in the risk of UTI, hypoglycemia, or volume depletion.

CONCLUSION

Based on the results from the PK and E-R analysis, no dose adjustment is required for empagliflozin in the patient population for which the drug is approved.

FUNDING

Boehringer Ingelheim.

Exposure-response modelling for empagliflozin, a sodium glucose cotransporter 2 (SGLT2) inhibitor, in patients with type 2 diabetes

AIMS

To provide model-based clinical development decision support including dose selection guidance for empagliflozin, an orally administered sodium glucose cotransporter 2 inhibitor, through developed exposure-response (E-R) models for efficacy and tolerability in patients with type 2 diabetes mellitus (T2DM).

METHODS

Five randomized, placebo-controlled, multiple oral dose studies of empagliflozin in patients with T2DM (n = 974; 1-100 mg once daily, duration ≤12 weeks) were used to develop E-R models for efficacy (glycosylated haemoglobin [HbA1c ], fasting plasma glucose [FPG] and urinary glucose excretion). Two studies (n = 748, 12 weeks) were used to evaluate tolerability E-R.

RESULTS

The efficacy model predicted maximal decreases in FPG and HbA1c of 16% and 0.6%, respectively, assuming a baseline FPG concentration of 8 mm (144 mg dl(-1) ) and 10-25 mg every day empagliflozin targeted 80-90% of these maximums. Increases in exposure had no effect on incidence rates of hypoglycaemia (n = 4), urinary tract infection (n = 17) or genital/vulvovaginal-related (n = 16) events, although low prevalence rates may have precluded more accurate evaluation.

CONCLUSIONS

E-R analyses indicated that 10 and 25 mg once daily empagliflozin doses achieved near maximal glucose lowering efficacy.

Biotransformation and mass balance of the SGLT2 inhibitor empagliflozin in healthy volunteers

1. The absorption, biotransformation and excretion of empagliflozin, an SGLT2 inhibitor, were evaluated in eight healthy subjects following a single 50 mg oral dose of empagliflozin containing ∼100 µCi [(14)C]-empagliflozin. 2. Radioactivity was rapidly absorbed, with plasma levels peaking 1 h post-dose. Total exposure was lower in blood versus plasma, consistent with moderate (28.6-36.8%) red blood cell partitioning. Protein binding was 80.3-86.2%. 3. Most of the radioactive dose was recovered in urine (54.4%) and faeces (41.1%). Unchanged empagliflozin was the most abundant drug-related component in plasma, representing 75.5-77.4% of plasma radioactivity and 79.6% plasma radioactivity AUC0-12 h. Unchanged empagliflozin was the most abundant drug-related component in urine and faeces, representing 43.5% (23.7% of dose) and 82.9% (34.1% of dose) of radioactivity in urine and faeces, respectively. Six metabolites were identified in plasma: three glucuronide conjugates representing 4.7-7.1% of AUC0-12 h and three less abundant metabolites (<0.2-1.9% AUC0-12 h). The most abundant metabolites in urine were two glucuronide conjugates (7.8-13.2% of dose) and in faeces was a tetrahydrofuran ring-opened carboxylic acid metabolite (1.9% of dose). 4. To conclude, empagliflozin was rapidly absorbed and excreted primarily unchanged in urine and faeces. Unchanged parent was the major drug-related component in plasma. Metabolism was primarily via glucuronide conjugation.

Effect of renal impairment on the pharmacokinetics, pharmacodynamics, and safety of empagliflozin, a sodium glucose cotransporter 2 inhibitor, in Japanese patients with type 2 diabetes mellitus

PURPOSE

The purpose of this study was to assess the effect of renal impairment on the pharmacokinetic, pharmacodynamic, and safety profiles of empagliflozin, a sodium glucose cotransporter 2 (SGLT2) inhibitor, in Japanese patients with type 2 diabetes mellitus (T2DM).

METHODS

In an open-label, parallel-group study, 32 Japanese patients with T2DM and different degrees of renal function (n = 8 per renal function category: normal renal function, estimated glomerular filtration rate [eGFR; Japanese equation] ≥90 mL/min/1.73 m(2); mild renal impairment, eGFR of 60-<90 mL/min/1.73 m(2); moderate renal impairment, eGFR of 30-<60 mL/min/1.73 m(2); and severe renal impairment, eGFR of 15-<30 mL/min/1.73 m(2)) received a single 25 mg dose of empagliflozin.

FINDINGS

Empagliflozin exposure increased with increasing renal impairment. Maximum empagliflozin plasma concentrations were similar among all renal function groups. Adjusted geometric mean ratios for extent of exposure (AUC0-∞) to empagliflozin versus normal renal function were 128.8% (95% CI, 106.0-156.6%), 143.8% (95% CI, 118.3-174.8%), and 152.3% (95% CI, 125.3-185.2%) for patients with mild, moderate, and severe renal impairment, respectively. Decreases in renal clearance of empagliflozin correlated with eGFR. Urinary glucose excretion decreased with increasing renal impairment and correlated with eGFR (adjusted mean [SE] change from baseline: 75.0 [4.84] g, 62.6 [5.75] g, 57.9 [4.86] g, and 23.7 [5.24] g for patients with normal renal function and mild, moderate, and severe renal impairment, respectively). Only 2 patients (6%) had adverse events; both were mild.

IMPLICATIONS

Pharmacokinetic data suggest that no dose adjustment of empagliflozin is necessary in Japanese patients with T2DM and renal impairment because increases in exposure were <2-fold. Urinary glucose excretion decreased with increasing renal impairment. ClinicalTrials.gov identifier: NCT01581658.

Pharmacokinetics, pharmacodynamics and safety of empagliflozin, a sodium glucose cotransporter 2 (SGLT2) inhibitor, in subjects with renal impairment

AIMS

Empagliflozin is a selective sodium glucose cotransporter 2 (SGLT2) inhibitor that inhibits renal glucose reabsorption and is being investigated for the treatment of type 2 diabetes mellitus (T2DM).

METHODS

In this open-label study, the effect of renal impairment on the pharmacokinetics, pharmacodynamics and safety of a 50 mg dose of empagliflozin was investigated in 40 subjects, grouped according to estimated glomerular filtration rate (eGFR).

RESULTS

Maximum empagliflozin plasma concentrations were similar in subjects with normal renal function and renal impairment. Area under the empagliflozin concentration-time curve (AUC0 -∞ ) values increased by approximately 18, 20, 66 and 48% in subjects with mild, moderate, severe renal impairment and renal failure/end stage renal disease (ESRD), respectively, in comparison to healthy subjects. This was attributed to decreased renal clearance (CLR ). Urinary glucose excretion (UGE) decreased with increasing renal impairment and correlated with decreased eGFR and CLR . Empagliflozin was well tolerated, with no increase in adverse events associated with renal impairment.

CONCLUSIONS

Renal insufficiency resulted in decreased CLR of empagliflozin, moderately increased systemic exposure and decreased UGE. A single 50 mg dose of empagliflozin was well tolerated in subjects with normal renal function and any degree of renal impairment. The pharmacokinetic results of this study indicate that no dose adjustment of empagliflozin is required in patients with renal impairment.

Pharmacokinetics, safety and tolerability of empagliflozin, a sodium glucose cotransporter 2 inhibitor, in patients with hepatic impairment

AIMS

This open-label, parallel-group study investigated the effect of various degrees of hepatic impairment on the pharmacokinetics, safety and tolerability of the sodium glucose cotransporter 2 inhibitor empagliflozin.

METHODS

Thirty-six subjects [8 each with mild, moderate or severe hepatic impairment (Child-Pugh classification), and 12 matched controls with normal hepatic function] received a single 50 mg dose of empagliflozin.

RESULTS

Empagliflozin was rapidly absorbed. After reaching peak levels, plasma drug concentrations declined in a biphasic fashion. Compared with subjects with normal hepatic function, geometric mean ratios (90% confidence interval) of AUC(0-∞) and C(max) were 123.15% (98.89-153.36) and 103.81% (82.29-130.95), respectively, in patients with mild hepatic impairment, 146.97% (118.02-183.02) and 123.31% (97.74-155.55), respectively, in patients with moderate hepatic impairment, and 174.70% (140.29-217.55) and 148.41% (117.65-187.23), respectively, in patients with severe hepatic impairment. Adverse events, all mild or moderate in intensity, were reported in three subjects with moderate hepatic impairment, two subjects with severe hepatic impairment and six subjects with normal hepatic function.

CONCLUSIONS

Empagliflozin was well tolerated in subjects with hepatic impairment. Increases in empagliflozin exposure were less than twofold in patients with hepatic impairment; therefore no dose adjustment of empagliflozin is required in patients with hepatic impairment.

Safety, tolerability, pharmacokinetics, and pharmacodynamics of multiple rising doses of empagliflozin in patients with type 2 diabetes mellitus

INTRODUCTION

This study examined the safety, tolerability, pharmacokinetics, and pharmacodynamics of empagliflozin, a potent and highly selective sodium glucose cotransporter 2 (SGLT2) inhibitor, in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 48 patients with T2DM were randomized to receive one of four doses of empagliflozin (2.5, 10, 25, or 100 mg qd) or placebo over 8 days. In every dose group, nine patients received active drug and three received placebo. The primary endpoint was safety and tolerability. Pharmacokinetic and pharmacodynamic parameters were measured as secondary endpoints.

RESULTS

Empagliflozin was rapidly absorbed, reaching peak levels 1.5-3.0 h after dosing and showed a biphasic decline. The mean terminal elimination half-life ranged from 10 to 19 h. Increases in exposure (area under the plasma concentration-time curve [AUC] and maximum concentration of analyte in plasma [C max]) were approximately proportional with dose. Empagliflozin increased the rate and total amount of glucose excreted in urine compared to placebo. After administration of a single dose of empagliflozin, cumulative amounts of glucose excreted in urine over 24 h ranged from 46.3 to 89.8 g, compared with 5.84 g with placebo. Similar results were seen after multiple doses. Fasting plasma glucose levels decreased by 17.2-25.8% with empagliflozin and by 12.7% with placebo. The frequency of adverse events was 33.3-66.7% with empagliflozin and 41.7% with placebo. There were no changes in urine volume or micturition frequency under the controlled study conditions.

CONCLUSION

Overall, pharmacokinetic assessments demonstrated a dose-proportional increase in drug exposure and support once-daily dosing. Elevated urinary glucose excretion was observed with all doses. Multiple once-daily oral doses of empagliflozin (2.5-100 mg) reduced plasma glucose and were well tolerated in patients with T2DM. EudraCT (2007-000654-32).

Safety, tolerability, pharmacokinetics and pharmacodynamics following 4 weeks' treatment with empagliflozin once daily in patients with type 2 diabetes

AIM

To investigate the safety, tolerability, pharmacokinetics and pharmacodynamics of empagliflozin in patients with type 2 diabetes following oral administration of 10, 25 or 100 mg doses once daily over 28 days.

METHODS

A total of 78 patients were assigned to empagliflozin 10 mg (n = 16), 25 mg (n = 16) or 100 mg (n = 30) or placebo (n = 16) for 28 days. Assessments included adverse events (AEs) and pharmacokinetic and pharmacodynamic endpoints.

RESULTS

Empagliflozin exposure increased dose-proportionally over the dose range 10-100 mg and showed linear pharmacokinetics with respect to time. Urinary glucose excretion (UGE) increased from baseline to day 1 by 74, 90 and 81 g with empagliflozin 10, 25 and 100 mg, respectively. The increases in UGE were maintained over 28 days with multiple dosing. Virtually no change in UGE was observed in the placebo group. Significant reductions from baseline in mean daily plasma glucose and fasting plasma glucose were observed with empagliflozin compared with placebo. The incidence of AEs was similar in the empagliflozin and placebo groups (50.0, 56.3 and 66.7% with empagliflozin rising doses and 62.5% with placebo). The most frequently reported AEs were pollakiuria (10.3%), nasopharyngitis (9.0%), constipation (9.0%) and headache (7.7%).

CONCLUSIONS

Oral administration of empagliflozin at doses of 10, 25 or 100 mg once daily over 28 days resulted in significant increases in UGE and reductions in blood glucose compared with placebo, and were well tolerated in patients with type 2 diabetes.

The sodium glucose cotransporter 2 inhibitor empagliflozin does not prolong QT interval in a thorough QT (TQT) study

Background

Empagliflozin is a potent, selective sodium glucose cotransporter 2 (SGLT2) inhibitor in development as an oral antidiabetic treatment. This QT interval study assessed potential effects of empagliflozin on ventricular repolarisation and other electrocardiogram (ECG) parameters.

Methods

A randomised, placebo-controlled, single-dose, double-blind, five-period crossover study incorporating a novel double-placebo period design to reduce sample size, while maintaining full statistical power. Treatments: single empagliflozin doses of 25 mg (therapeutic) and 200 mg (supratherapeutic), matching placebo and open-label moxifloxacin 400 mg (positive control). Triplicate 12-lead ECGs of 10 second duration were recorded at baseline and during the first 24 hours after dosing. The primary endpoint was mean change from baseline (MCfB) in the population heart rate-corrected QT interval (QTcN) between 1–4 hours after dosing.

Results

Thirty volunteers (16 male, 14 female, mean [range] age: 34.5 [18–52] years) were randomised. The placebo-corrected MCfB in QTcN 1–4 hours after dosing was 0.6 (90% CI: -0.7, 1.9) ms and -0.2 (-1.4, 0.9) ms for empagliflozin 25 mg and 200 mg, respectively, below the ICH E14 defined threshold of regulatory concern 10 ms. Assay sensitivity was confirmed by a placebo-corrected MCfB in QTcN 2–4 hours post-dose of 12.4 (10.7, 14.1) ms with moxifloxacin 400 mg. Empagliflozin tolerability was good for all volunteers; 23.3% experienced adverse events (AEs) with empagliflozin and 27.6% with placebo. The most frequent AE was nasopharyngitis.

Conclusions/interpretation

Single doses of empagliflozin 25 mg and 200 mg were not associated with QTcN prolongation and were well tolerated in healthy volunteers.

Trial registration

ClinicalTrials.gov: NCT01195675

Lack of drug-drug interaction between empagliflozin, a sodium glucose cotransporter 2 inhibitor, and warfarin in healthy volunteers

AIM

To investigate potential drug-drug interactions between empagliflozin and warfarin.

METHODS

Healthy subjects (n = 18) received empagliflozin 25 mg qd for 5 days (treatment A), followed by empagliflozin 25 mg qd for 7 days (days 6-12) with a single 25 mg dose of warfarin on day 6 (treatment B), and a single 25 mg dose of warfarin alone (treatment C), in an open-label, crossover study. Subjects received treatments in sequence AB_C or C_AB with a washout period of ≥14 days between AB and C or C and AB.

RESULTS

Warfarin had no effect on empagliflozin area under concentration-time curve or maximum plasma concentration at steady-state (AUC(τ,ss) or C(max,ss)): geometric mean ratios (GMRs) (90% confidence intervals [CI]) were 100.89% (96.86, 105.10) and 100.64% (89.79, 112.80), respectively. Empagliflozin had no effect on AUC from 0 h to infinity (AUC(0-∞)) or C(max) for R- or S-warfarin (GMRs [90% CI] for AUC(0-∞): 98.49% [95.29, 101.80] and 95.88% [93.40, 98.43], respectively; C(max): 97.89% [91.12, 105.15] and 98.88% [91.84, 106.47], respectively). Empagliflozin had no clinically relevant effects on warfarin's anticoagulant activity (international normalised ratio [INR]) (GMR [95% CI] for peak INR: 0.87 [0.73, 1.04]; area under the effect-time curve from 0 to 168 h: 0.88 [0.79, 0.98]. No drug-related adverse events were reported for empagliflozin after monotherapy or combined administration. The combination of empagliflozin and warfarin was well tolerated.

CONCLUSIONS

No drug-drug interactions were observed between empagliflozin and warfarin, indicating that empagliflozin and warfarin can be co-administered without dosage adjustments of either drug.

Pharmacokinetics of empagliflozin, a sodium glucose cotransporter-2 (SGLT-2) inhibitor, coadministered with sitagliptin in healthy volunteers

INTRODUCTION

This randomized, open-label, crossover study investigated potential drug-drug interactions between the sodium glucose cotransporter-2 (SGLT-2) inhibitor empagliflozin and the dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin. Empagliflozin is a potent and selective SGLT-2 inhibitor that lowers blood glucose levels by inhibiting renal glucose reabsorption, leading to an increase in urinary glucose excretion. Sitagliptin lowers blood glucose through an insulin-dependent mechanism of action.

METHODS

Sixteen healthy male volunteers received three treatments (A, B, C) in one of two treatment sequences (AB then C, or C then AB). In treatment AB, 50 mg empagliflozin was administered once daily (q.d.) for 5 days (treatment A), immediately followed by coadministration of 50 mg empagliflozin q.d. and 100 mg sitagliptin q.d. over 5 days (treatment B). In treatment C, 100 mg sitagliptin was administered q.d. for 5 days. A washout period of ≥7 days separated treatments AB and C.

RESULTS

Coadministration of sitagliptin with empagliflozin did not have a clinically relevant effect on the area under the concentration-time curve of the analyte in plasma at steady state over a uniform dosing interval τ (AUC(τ,ss)) (geometric mean ratio [GMR] 110.4; 90% confidence interval [CI] 103.9, 117.3) or maximum measured concentration of the analyte in plasma at steady state over a uniform dosing interval τ (C (max,ss)) (GMR 107.6; 90% CI 97.0, 119.4) of empagliflozin. Coadministration of empagliflozin with sitagliptin did not have a clinically meaningful effect on the AUC(τ,ss) (GMR 103.1; 90% CI 98.9, 107.3) or C (max,ss) (GMR 108.5; 90% CI 100.7, 116.9) of sitagliptin. Empagliflozin and sitagliptin were well tolerated when given alone or in combination. Five subjects (31.3%) reported at least one adverse event (AE): three (18.8%) experienced an AE while receiving empagliflozin monotherapy and three (18.8%) while receiving sitagliptin monotherapy. No adverse events were reported during the coadministration period. No AEs were regarded as drug-related by the investigator.

CONCLUSION

These results indicate that empagliflozin and sitagliptin can be coadministered without dose adjustments.

Bioavailability of extended-release nevirapine 400 and 300 mg in HIV-1: a multicenter, open-label study

BACKGROUND

Nevirapine (NVP) is a widely used non-nucleoside reverse transcriptase inhibitor. A once-daily extended-release (XR) formulation would potentially increase adherence and thus efficacy.

OBJECTIVE

The aim of this study was to investigate the steady-state bioavailability of 2 once-daily tablet formulations of NVP XR (containing 25% or 20% hypromellose; NVP XR25 and NVP XR20, respectively) in 400- or 300-mg tablets compared with twice-daily immediate-release (IR) NVP 200-mg tablets.

METHODS

This Phase Ib multinational, multicenter, open-label trial was conducted in patients aged 18 to 60 years, infected with HIV-1 (viral load, ≤50 copies/mL), and treated for ≥12 weeks with twice-daily NVP IR 200 mg. Patients were switched to NVP XR25 400 or 300 mg or NVP XR20 400 or 300 mg for 19 days. Plasma samples were collected over 24-hour periods at steady state. Primary end points were AUC(0-24,ss), C(max,ss), and C(min,ss), analyzed using an ANOVA statistical model on the logarithmic scale and 2-sided 90% CI. Sample size was determined assuming an intrasubject %CV of 20% for C(max). Adverse events (AEs) and viral loads were monitored.

RESULTS

Ninety-two patients were enrolled (NVP XR25 400 mg, 24 patients; NVP XR20 400 mg, 24; NVP XR25 300 mg, 21; NVP XR20 300 mg, 23). Compared with NVP IR, the AUC(0-24,ss) values of the NVP XR formulations were lower (test/reference ratios: 79.5% [90% CI, 73.0-86.7; P = 0.544], 71.0% [90% CI, 63.3-79.7; P = 0.956], 90.3% [90% CI, 80.4-101.4; P = 0.044], and 83.7% [90% CI, 77.9-89.9; P = 0.148] with NVP XR25 400 mg, NVP XR20 400 mg, NVP XR25 300 mg, and NVP XR20 300 mg, respectively). The relative bioavailability of NVP XR25 was greater compared with that of NVP XR20. C(max,ss) values were lower with all NVP XR formulations compared with NVP IR. For C(min,ss), NVP XR25 400 and 300 mg were not significantly different from NVP IR, with 90% CIs within the range of 80% to 125% (P = 0.039 and P = 0.017, respectively). All AEs were mild or moderate, with no significant differences between treatment groups. No virologic failures (viral load, >50 copies/mL over 2 consecutive readings) were observed.

CONCLUSIONS

Extent of bioavailability was lower and t(max,ss) was delayed with all NVP XR formulations compared with NVP IR. The bioavailability of the NVP XR25 formulations was greater than that of the NVP XR20 formulations. C(min,ss) with NVP XR25 was similar to that with NVP IR. All of the NVP XR formulations were well tolerated. The 400-mg NVP XR25 formulation was selected for further development.

In vitro-in vivo correlation for nevirapine extended release tablets

An in vitro-in vivo correlation (IVIVC) for four nevirapine extended release tablets with varying polymer contents was developed. The pharmacokinetics of extended release formulations were assessed in a parallel group study with healthy volunteers and compared with corresponding in vitro dissolution data obtained using a USP apparatus type 1. In vitro samples were analysed using HPLC with UV detection and in vivo samples were analysed using a HPLC-MS/MS assay; the IVIVC analyses comparing the two results were performed using WinNonlin. A Double Weibull model optimally fits the in vitro data. A unit impulse response (UIR) was assessed using the fastest ER formulation as a reference. The deconvolution of the in vivo concentration time data was performed using the UIR to estimate an in vivo drug release profile. A linear model with a time-scaling factor clarified the relationship between in vitro and in vivo data. The predictability of the final model was consistent based on internal validation. Average percent prediction errors for pharmacokinetic parameters were <10% and individual values for all formulations were <15%. Therefore, a Level A IVIVC was developed and validated for nevirapine extended release formulations providing robust predictions of in vivo profiles based on in vitro dissolution profiles.

Mechanism of ganciclovir uptake by rabbit retina and human retinal pigmented epithelium cell line ARPE-19

PURPOSE

The objective of this study was to elucidate the mechanism of ganciclovir uptake by the rabbit retina and the human retinal pigmented epithelium cell line ARPE-19.

MATERIALS AND METHODS

[(3)H]Adenine, [(3)H]adenosine, [(3)H]thymidine, and [(3)H]ganciclovir were used to elucidate the mechanism of ganciclovir uptake by the ARPE-19 cell line and the isolated rabbit retinal tissue. Uptake studies using ARPE-19 cell line and isolated rabbit retina were carried out at 37 degrees C and 25 degrees C, respectively, for 5 min.

RESULTS

Uptake of [(3)H]adenine by ARPE-19 cells decreased by 95% in the presence of unlabeled adenine. Other nucleobases such as guanine, thymine, and uracil and the nucleosides adenosine, guanosine, thymidine, uridine, and inosine also reduced uptake of [(3)H]adenine by the ARPE-19 cells. Although [(3)H]adenosine and [(3)H]thymidine uptake was inhibited by nucleosides, nucleobases did not demonstrate any inhibitory effect, indicating that nucleosides can only bind to the nucleobase transporter but are not translocated by it. Uptake of the nucleosides and nucleobases by the ARPE-19 cells was sodium and pH independent. [(3)H]adenosine and [(3)H]thymidine uptake by the ARPE-19 cells was inhibited by nanomolar quantities of nitrobenzylthioinosine. Uptake of [(3)H]adenine by the isolated rabbit retina was drastically reduced in the presence of unlabeled adenine. Unlabeled thymidine and guanosine, and removal of sodium from the uptake medium, inhibited uptake of [(3)H]thymidine by the rabbit retina. Nucleosides, nucleobases, and unlabeled ganciclovir did not exhibit any inhibitory effect on [(3)H]ganciclovir uptake by the isolated rabbit retina or ARPE-19 cells.

CONCLUSIONS

Our results indicate that although the rabbit retina and the ARPE-19 cell line express nucleoside and nucleobase transporters, translocation of ganciclovir does not involve any carrier-mediated transport process. Rather, ganciclovir uptake by the rabbit retina and ARPE-19 cells is governed primarily by passive diffusion.

Biotransformation and mass balance of tipranavir, a nonpeptidic protease inhibitor, when co-administered with ritonavir in Sprague-Dawley rats

In this study, tipranavir (TPV) biotransformation and disposition when co-administered with ritonavir (RTV) were characterized in Sprague-Dawley rats. Rats were administered a single intravenous (5 mg kg(-1)) or oral (10 mg kg(-1)) dose of [(14)C]TPV with co-administration of RTV (10 mg kg(-1)). Blood, urine, faeces and bile samples were collected at specified time-points over a period of 168 h. Absorption of TPV-related radioactivity ranged from 53.2-59.6%. Faecal excretion was on average 86.7% and 82.4% (intravenous) and 75.0% and 82.0% (oral) of dosed radioactivity in males and females, respectively. Urinary excretion was on average 4.06% and 6.73% (intravenous) and 9.71% and 8.28% (oral) of dosed radioactivity in males and females, respectively. In bile-duct-cannulated rats, 39.8% of the dose was recovered in bile. After oral administration, unchanged TPV accounted for the majority of the radioactivity in plasma (85.7-96.3%), faeces (71.8-80.1%) and urine (33.3-62.3%). The most abundant metabolite in faeces was an oxidation metabolite R-2 (5.9-7.4% of faecal radioactivity, 4.4-6.1% of dose). In urine, no single metabolite was found to be significant, and comprised <1% of dose. TPV when co-administered with RTV to rats was mainly excreted in feces via bile and the parent compound was the major component in plasma and faeces.

Ocular disposition of novel lipophilic diester prodrugs of ganciclovir following intravitreal administration using microdialysis

PURPOSE

The objective of the present study was to explore acyl diester prodrugs (acetate, propionate, and butyrate) of ganciclovir (GCV) to achieve sustained therapeutic concentrations of GCV in the vitreous over a prolonged period of time following intravitreal administration.

METHODS

Male New Zealand albino rabbits (2-2.5 kg) were used for these studies. Animals were kept under anesthesia throughout the course of an experiment using ketamine HCl and xylazine. A concentric microdialysis probe was implanted into the vitreous chamber with a 21-gauge needle and a linear microdialysis probe was inserted into the anterior chamber across the cornea using a 25-gauge needle. The probes were perfused with isotonic phosphate buffer saline (pH 7.4) at a flow rate of 2 microl/min. GCV prodrugs (33.2 microg of diacetate, 35.9 microg dipropionate prodrugs, and 9.87 microg of dibutyrate prodrug) or GCV (50, 25, and 12.5 microg) were administered intravitreally and the microdialysis samples were collected every 20 minutes over a period of 10 hours.

RESULTS

Vitreal terminal elimination half-life of GCV was found to be similar with all three doses and ranged from 325 to 401 min. Elimination rate constant (lambda z) and vitreal clearance of diesters increased with the ester chain length. Vitreal elimination half-lives of GCV diacetate, dipropionate, and dibutyrate esters were found to be 112 +/- 37, 41.9 +/- 13.1, and 33.5 +/- 6.5 min, respectively. Mean residence time (MRT) of regenerated GCV (356 +/- 16 min, 341 +/- 11 min and 324 +/- 19 min from GCV diacetate, dipropionate and dibutyrate, respectively) increased by 2-fold following prodrug administration as compared to direct GCV administration (185 +/- 28 min).

CONCLUSIONS

GCV showed linear kinetics in the dose range studied. Acyl diester prodrugs of GCV generated therapeutic concentrations of GCV in vivo. Moreover, these studies have shown that MRT of GCV could be enhanced about 2-fold through prodrug modification.

Ocular disposition of ganciclovir and its monoester prodrugs following intravitreal administration using microdialysis

The present study was carried out to delineate the ocular pharmacokinetics of ganciclovir (GCV) following intravitreal administration. Another objective was to achieve sustained therapeutic concentrations of GCV in the vitreous over a prolonged period of time using its acyl monoester prodrugs (acetate, propionate, butyrate, and valerate). New Zealand albino male rabbits (2-2.5 kg) were kept under anesthesia. A concentric microdialysis probe was implanted in the vitreous using a 21-guage needle, and a linear microdialysis probe was implanted in the anterior chamber across the cornea using a 25-guage needle. The probes were perfused with isotonic phosphate buffer saline (pH 7.4) at a flow rate of 2 microl/min. The drugs were administered (0.2 micromoles) intravitreally and the samples were collected every 20 min over a period of 10 h. The vitreal terminal elimination half-life (t(1/2)beta) of GCV was found to be 426 +/- 109 min. The hydrolysis rate and vitreal clearance of the prodrugs increased with the ascending ester chain length. The vitreal elimination half-lives (t(1/2k10)) of GCV, acetate, propionate, butyrate, and valerate esters of GCV were 170 +/- 37, 117 +/- 50, 122 +/- 13, 55 +/- 26, and 107 +/- 14 min, respectively. A parabolic relationship was observed between the vitreal elimination rate constant and the ester chain length. Mean residence time (MRT) of the regenerated GCV following prodrug administration was found to be three to four times the value obtained after GCV injection. In conclusion, these studies have shown that the ester prodrugs generated therapeutic concentrations of GCV in vivo, and the MRT of GCV could be enhanced by 3- to 4-fold through prodrug modification.

Ocular pharmacokinetics of cephalosporins using microdialysis

The purpose of this study was to delineate the ocular pharmacokinetics of cephalosporins and investigate the presence of peptide transporters in the retina. New Zealand albino rabbits were kept under anesthesia. A concentric microdialysis probe was implanted in the vitreous chamber and linear probe across the cornea in the aqueous humor. Isotonic phosphate buffer saline was perfused through the probes, and samples were collected every 20 min over a period of 10 hr. A 500 microg dose of cephalexin, cephazolin, and cephalothin was administered intravitreally. Inhibition experiments were carried out in vivo, using gly-pro and gly-sar. The vitreal half-lives of cephalexin, cefazolin, and cephalothin were 185.38 +/- 27.25 min, 111.40 +/- 17.17 min, and 146.68 +/- 47.52 min, respectively. Cephalexin generated higher aqueous humor concentrations compared to cefazolin. The pharmacokinetic parameters of cephalexin in the presence of gly-pro, i.e., AUC (44452.06 +/- 3326.55 microg x min/ml), clearance (0.0013 +/- 0.0004 ml/min) and vitreal half-life (825.12 +/- 499.95 min) were different from that of the control (14612.83 +/- 4036.47 microg x min/ml, 0.0036 +/- 0.0011 ml/min, and 187.96 +/- 65.12 min, respectively). Gly-pro did not inhibit cefazolin, and gly-sar showed no effect on the pharmacokinetics of both drugs. These studies indicate the involvement of a peptide carrier in the transport of cephalosporins across the retina. Although gly-pro inhibited the elimination of cephalexin from the vitreous, the effect of an alpha-amino group on peptide carriers was not clearly evident.

Ocular pharmacokinetics in rabbits using a novel dual probe microdialysis technique

Ocular infections involve delicate internal structures of the eye that often require treatment with antimicrobial agents. A major constraint to the study of ocular drug absorption from systemic administration is the inaccessibility of the vitreous for continuous serial sampling. A novel dual probe microdialysis technique has been employed in our laboratory, which will enable the delineation of complete ocular pharmacokinetics of a drug. New Zealand albino rabbits weighing 2--2.5 kg were used. The animals were kept under anesthesia throughout the experiment. A concentric probe was implanted in the vitreous chamber about 3 mm below the corneal scleral limbus. Simultaneously a linear probe was implanted in the anterior chamber across the cornea. Intraocular pressure (IOP) was measured using Schiotz tonometer. The total protein concentrations in the aqueous and vitreous humors were determined using the Bio-Rad protein assay method. The aqueous and vitreous elimination kinetics of fluorescein were studied after intravitreal and systemic administrations over a period of 10 hr. Microdialysis technique was also compared to the conventional direct sampling technique by determining the intravitreal kinetics of fluorescein. Results suggest that IOP reverted to normal within 2 hr after the implantation of the probes. The increase in the vitreal total protein concentration was not significantly different from the baseline. The increase in the aqueous total protein concentration was less than five times the basal concentration throughout the experiment. The blood-aqueous and blood-retinal barrier integrity was delineated by determining the permeability index for fluorescein and were found to be 9.48 +/- 4.25% and 1.99 +/- 0.66% for the anterior and vitreous chamber, respectively. The rate constant of penetration of fluorescein into the anterior chamber was found to be 8.48 +/- 1.33 x 10(-2) min(-1), which was significantly higher than into the vitreous i.e. 4.34 +/- 2.82 x 10(-2) min(-1). The terminal elimination rate constant of fluorescein from the anterior chamber (1.48 +/- 0.79 x 10(-2) min(-1)) was found to be similar to that of the plasma terminal elimination rate constant (1.57 +/- 0.25 x 10(-2) min(-1)), but significantly higher than from the vitreous (3.0 +/- 0.7 x 10(-3) min(-1)). The terminal vitreal elimination rate constant of fluorescein after intravitreal administration was found to be similar by both microdialysis (3.98 +/- 0.6 x 10(-3) min(-1)) and direct sampling (4.38 +/- 1.4 x 10(-3) min(-1)) techniques. In case of direct sampling technique the area under the vitreous concentration-time curve was higher compared to that obtained by the microdialysis technique. There was no breakdown of the blood ocular barriers as shown by a very small change in the intraocular fluid protein concentrations. This was also confirmed by the fluorescein kinetics, which were in accordance with the previous studies. IOP data suggests that the intraocular fluid dynamics were not affected and the animals stabilized within 2 hr after the implantation of the probes. Fluorescein data suggests that the vitreous compartment is surrounded by a tighter barrier compared to the anterior chamber. This technique appears to be more sensitive, reproducible and requires only one animal for the determination of entire ocular pharmacokinetic profile.