Silke Retlich

Hospital De Clínicas De Porto Alegre, Porto Alegre, Estado do Rio Grande do Sul, Brazil

Are you Silke Retlich?

Claim your profile

Publications (9)26.26 Total impact

  • Article: Pharmacokinetic and Pharmacodynamic Evaluation of Linagliptin in African American Patients with Type 2 Diabetes Mellitus.
    [show abstract] [hide abstract]
    ABSTRACT: AIM: This was an open-label, multicenter phase I trial to study the pharmacokinetics and pharmacodynamics of the dipeptidyl peptidase-4 (DPP-4) inhibitor linagliptin in African American patients with type 2 diabetes mellitus (T2DM). METHODS: Forty-one African American patients with type 2 diabetes mellitus were included in this study. Patients were admitted to a study clinic and administered 5 mg linagliptin once-daily for 7 days, followed by 7 days of outpatient evaluation. RESULTS: Primary endpoints were area under the plasma concentration-time curve (AUC), maximum plasma concentration (C(max) ), and plasma DPP-4 trough inhibition at steady state. Linagliptin geometric mean AUC was 194 nmol/L·h (geometric coefficient of variation, 26%), with a C(max) of 16.4 nmol/L (41%). Urinary excretion was low (0.5% and 4.4% of the dose excreted over 24 hours, days 1 and 7). The geometric mean DPP-4 inhibition at steady state was 84.2% at trough and 91.9% at maximum. The exposure range and overall pharmacokinetic/pharmacodynamic profile of linagliptin in this study of African Americans with T2DM was comparable with that in other populations. Laboratory data, vital signs, and physical exams did not show any relevant findings. No safety concerns were identified. CONCLUSIONS: The results of this study in African American patients with T2DM support the use of the standard 5 mg dose recommended in all populations.
    British Journal of Clinical Pharmacology 01/2013; · 2.96 Impact Factor
  • Article: A novel model-based meta-analysis to indirectly estimate the comparative efficacy of two medications: an example using DPP-4 inhibitors, sitagliptin and linagliptin, in treatment of type 2 diabetes mellitus.
    [show abstract] [hide abstract]
    ABSTRACT: To develop a longitudinal statistical model to indirectly estimate the comparative efficacies of two drugs, using model-based meta-analysis (MBMA). Comparison of two oral dipeptidyl peptidase (DPP)-4 inhibitors, sitagliptin and linagliptin, for type 2 diabetes mellitus (T2DM) treatment was used as an example. Systematic review with MBMA. MEDLINE, EMBASE, http://www.ClinicalTrials.gov, Cochrane review of DPP-4 inhibitors for T2DM, sitagliptin trials on Food and Drug Administration website to December 2011 and linagliptin data from the manufacturer. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Double-blind, randomised controlled clinical trials, ≥12 weeks' duration, that analysed sitagliptin or linagliptin efficacies as changes in glycated haemoglobin (HbA1c) levels, in adults with T2DM and HbA1c >7%, irrespective of background medication. MODEL DEVELOPMENT AND APPLICATION: A Bayesian model was fitted (Markov Chain Monte Carlo method). The final model described HbA1c levels as function of time, dose, baseline HbA1c, washout status/duration and ethnicity. Other covariates showed no major impact on model parameters and were not included. For the indirect comparison, a population of 1000 patients was simulated from the model with a racial composition reflecting the average racial distribution of the linagliptin trials, and baseline HbA1c of 8%. The model was developed using longitudinal data from 11 234 patients (10 linagliptin, 15 sitagliptin trials), and assessed by internal evaluation techniques, demonstrating that the model adequately described the observations. Simulations showed both linagliptin 5 mg and sitagliptin 100 mg reduced HbA1c by 0.81% (placebo-adjusted) at week 24. Credible intervals for participants without washout were -0.88 to -0.75 (linagliptin) and -0.89 to -0.73 (sitagliptin), and for those with washout, -0.91 to -0.76 (linagliptin) and -0.91 to -0.75 (sitagliptin). This study demonstrates the use of longitudinal MBMA in the field of diabetes treatment. Based on an example evaluating HbA1c reduction with linagliptin versus sitagliptin, the model used seems a valid approach for indirect drug comparisons.
    BMJ open. 01/2013; 3(3).
  • Article: Clinical pharmacokinetics and pharmacodynamics of linagliptin.
    [show abstract] [hide abstract]
    ABSTRACT: Linagliptin is an orally active small-molecule inhibitor of dipeptidyl peptidase (DPP)-4, which was first licensed in the US, Europe, Japan and other territories in 2011 to improve glycaemic control in adults with type 2 diabetes mellitus. Linagliptin is the first and thus far the only DPP-4 inhibitor, and oral antihyperglycaemic drug in general, to be approved as a single-strength once-daily dose (5 mg). Compared with other available DPP-4 inhibitors, linagliptin has a unique pharmacokinetic/pharmacodynamic profile that is characterized by target-mediated nonlinear pharmacokinetics, concentration-dependent protein binding, minimal renal clearance and no requirements for dose adjustment for any intrinsic or extrinsic factor. After single or multiple oral doses of 1-10 mg, linagliptin displays less than dose-proportional increases in maximum plasma concentration (C(max)) and area under the plasma concentration-time curve (AUC). Linagliptin is rapidly absorbed after oral administration, with C(max) occurring after approximately 90 minutes, and reaches steady-state concentrations within 4 days. With the therapeutic dose, steady-state C(max) (11-12 nmol/L) and AUC (∼150 nmol · h/L) are approximately 1.3-fold greater than after a single dose, indicating little drug accumulation with repeat dosing. Linagliptin exhibits concentration-dependent protein binding in human plasma in vitro (99% at 1 nmol/L to 75-89% at >30 nmol/L) and has a large apparent volume of distribution, demonstrating extensive distribution into tissues. The nonlinear pharmacokinetics of linagliptin are best described by a two-compartmental model that incorporates target-mediated drug disposition resulting from high-affinity, saturable binding to DPP-4. The oral bioavailability of linagliptin estimated with this model is approximately 30%. Linagliptin has a long terminal half-life (>100 hours); however, its accumulation half-life is much shorter (approximately 10 hours), accounting for the rapid attainment of steady state. The majority of linagliptin is eliminated as parent compound, demonstrating that metabolism plays a minor role in the overall pharmacokinetics in humans. The main, pharmacologically inactive S-3-hydroxypiperidinyl metabolite accounted for approximately 17% of the total drug-related compounds in plasma. Linagliptin is eliminated primarily in faeces, with only around 5% of the oral therapeutic dose excreted in the urine at steady state. Linagliptin potently inhibits DPP-4 (inhibition constant 1 nmol/L), and trough drug concentrations achieved with therapeutic dosing inhibit >80% of plasma DPP-4 activity, the threshold associated with maximal antihyperglycaemic effects in animal models. There are no clinically relevant alterations in linagliptin pharmacokinetics resulting from renal impairment, hepatic impairment, coadministration with food, race, body weight, sex or age. In vitro, linagliptin is a weak substrate and weak inhibitor of cytochrome P450 (CYP) 3A4 and permeability glycoprotein (P-gp) but not of other CYP isozymes or ATP-binding cassette transporters. Clinical studies have revealed no relevant drug interactions when coadministered with other drugs commonly prescribed to patients with type 2 diabetes, including the narrow therapeutic index drugs warfarin and digoxin. Linagliptin plasma exposure is reduced by potent inducers of CYP3A4 or P-gp. Linagliptin has demonstrated a large safety window (>100-fold the recommended daily dose) and clinically relevant antihyperglycaemic effects in patients with type 2 diabetes.
    Clinical Pharmacokinetics 05/2012; 51(7):411-27. · 5.40 Impact Factor
  • Article: The concentration-dependent binding of linagliptin (BI 1356) and its implication on efficacy and safety.
    [show abstract] [hide abstract]
    ABSTRACT: Linagliptin (BI 1356) is a dipeptidyl peptidase-4 (DPP-4) inhibitor for treatment of Type 2 diabetes which recently gained approval in the US, Europe, and Japan. Linagliptin showed nonlinear pharmacokinetics after intravenous and oral administration, which is due to a concentration-dependent protein binding of linagliptin to its target enzyme DPP-4. The aim of this analysis was to investigate this target-mediated binding of linagliptin and its implication on efficacy and safety. Pharmacokinetic modeling and simulations were performed using a two-compartment model with concentration-dependent binding in the central and in one peripheral compartment. The optimum therapeutic dose with minimal off-target side effects was simulated assuming that an antidiabetic effect of linagliptin was due to the linagliptin concentration bound to DPP-4 and that off-target side effects were related to free linagliptin. The difference between steady state AUCs of specifically bound and free linagliptin was maximized at oral doses of 2 - 5 mg. Since plasma DPP-4 inhibition increased slightly from 2.5 to 10 mg, pharmacokinetic simulations and the pharmacodynamic measurements taken together suggest that 5 mg linagliptin could be considered an optimum dose. Simulations with missed doses and additional doses at steady state showed the effect on DPP-4 bound linagliptin and change in DPP-4 inhibition was minimal after missing one 5 mg oral dose of linagliptin while two doses of 5 mg linagliptin resulted in a less than proportional increase of steady state AUC of free linagliptin. Results from modeling and simulation support a stable antidiabetic effect of linagliptin over 24 h at steady state and further indicate a low risk for off-target side effects.
    International journal of clinical pharmacology and therapeutics 05/2012; 50(5):323-30. · 1.18 Impact Factor
  • Article: Pharmacokinetics of linagliptin in subjects with hepatic impairment.
    [show abstract] [hide abstract]
    ABSTRACT: • Linagliptin is an oral, highly selective dipeptidyl peptidase-4 (DPP-4) inhibitor that was approved in the United States, Europe and elsewhere in 2011 for the treatment of type 2 diabetes mellitus. • The elimination of linagliptin is primarily non-renal. Therefore, a potential effect of hepatic impairment on the elimination of linagliptin may have important implications for dosing recommendations. • This study shows that mild, moderate or severe hepatic impairment did not result in an increase in linagliptin exposure after single and multiple dosing as compared with normal hepatic function. • No linagliptin dose adjustment is required in patients with any degree of hepatic impairment. To investigate whether hepatic impairment affects linagliptin pharmacokinetics, pharmacodynamics and tolerability. This open label, parallel group, single centre study enrolled patients with mild (n= 8), moderate (n= 9) or severe (n= 8) hepatic impairment and healthy subjects (n= 8). Groups were matched with regard to age, weight and gender. Primary endpoints were linagliptin exposure following 5 mg linagliptin once daily for 7 days in patients with mild and moderate hepatic impairment vs. healthy subjects or after a single 5 mg dose for patients with severe hepatic impairment vs. healthy subjects. In mild hepatic impairment, steady-state linagliptin exposure was slightly lower than in healthy subjects [AUC(τ,ss) geometric mean ratio (GMR) 75.5%, 90% confidence interval (CI) 61.6%, 92.5%, and C(max,ss) GMR 64.4%, 90% CI 43.2%, 96.0%]. Exposure also tended to be lower in moderate hepatic impairment (AUC(τ,ss) GMR 85.5%, 90% CI 70.2%, 104.2% and C(max,ss) GMR 92.3%, 90% CI 62.8%, 135.6%). After a single dose, AUC(0,24 h) in patients with severe hepatic impairment was similar to that in healthy subjects (GMR 100.4%, 90% CI 75.0%, 134.3%) and C(max) was lower (GMR 77.0%, 90% CI 44.9%, 132.3%). Accumulation based on AUC or C(max) and renal excretion of unchanged linagliptin (≤ 7%) were comparable across groups. Median plasma DPP-4 inhibition was similar in healthy subjects (91%), and patients with mild (90%) and moderate (89%) hepatic impairment at steady-state trough concentrations, and in patients with severe hepatic impairment 24 h after a single dose (84%). Linagliptin was well tolerated. Mild, moderate or severe hepatic impairment did not result in an increase in linagliptin exposure after single and multiple dosing compared with normal hepatic function. Dose adjustment with linagliptin is not required in patients with hepatic impairment.
    British Journal of Clinical Pharmacology 01/2012; 74(1):75-85. · 2.96 Impact Factor
  • Article: Effect of renal impairment on the pharmacokinetics of the dipeptidyl peptidase-4 inhibitor linagliptin(*).
    [show abstract] [hide abstract]
    ABSTRACT: This study assessed the influence of various degrees of renal impairment on the exposure of linagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor with a primarily non-renal route of excretion, in subjects with type 2 diabetes mellitus (T2DM). Linagliptin pharmacokinetics was studied under single-dose and steady-state conditions in subjects with mild, moderate and severe renal impairment (with and without T2DM) and end-stage renal disease and compared with the pharmacokinetics in subjects with normal renal function (with and without T2DM). Renal excretion of unchanged linagliptin was <7% in all groups. Under single-dose conditions, the degree of renal impairment did not affect mean plasma linagliptin concentration-time profiles. These showed a similar decline and almost identical plasma concentrations 24 h postdosing in subjects with mild, moderate or severe renal impairment and in subjects with T2DM with and without renal impairment. Although there was a tendency towards slightly higher (20-60%) exposure in renally impaired subjects (with and without T2DM) compared with subjects with normal renal function, the steady-state AUC and C(max) values showed a large overlap and were not affected by the degree of renal impairment. The accumulation half-life of linagliptin ranged from 14-15 h in subjects with normal renal function to 18 h in severe renal impairment. Only a weak correlation (r(2) = 0.18) was seen between creatinine clearance and steady-state exposure. Renal impairment has only a minor effect on linagliptin pharmacokinetics. Consequently, there will be no need for adjusting the linagliptin dose in renally impaired patients with T2DM.
    Diabetes Obesity and Metabolism 06/2011; 13(10):939-46. · 3.38 Impact Factor
  • Article: Pharmacokinetics and pharmacodynamics of single rising intravenous doses (0.5 mg-10 mg) and determination of absolute bioavailability of the dipeptidyl peptidase-4 inhibitor linagliptin (BI 1356) in healthy male subjects.
    [show abstract] [hide abstract]
    ABSTRACT: Linagliptin (BI 1356) is a highly specific inhibitor of dipeptidyl peptidase (DPP)-4, which is currently in phase III clinical development for the treatment of type 2 diabetes mellitus. Linagliptin exhibits nonlinear pharmacokinetics after oral administration, which are mainly related to concentration-dependent binding of linagliptin to its target, DPP-4. The objectives of the study were to investigate the pharmacokinetics and pharmacodynamics after intravenous administration of linagliptin and to determine its absolute bioavailability (F). This was a single rising-dose, randomized, four-group, placebo-controlled, single-blind (within dose groups) study. Thirty-six healthy men aged 18-50 years were enrolled and randomized into four sequential treatment groups. Group 1 received linagliptin 0.5 mg intravenously, group 2 received 2.5 mg intravenously and group 4 received 10 mg intravenously. In group 3, subjects underwent a two-way randomized crossover, receiving 5 mg intravenously and a 10 mg oral tablet. Linagliptin concentrations in plasma and urine, as well as plasma DPP-4 activity, were determined by validated assays. Noncompartmental analysis and population pharmacokinetic modelling were performed. Linagliptin showed nonlinear pharmacokinetics after intravenous infusion of 0.5-10 mg, with a less than dose-proportional increase in exposure. Noncompartmental parameters were calculated on the basis of total (i.e. bound and unbound) plasma concentrations. The total clearance value was low and increased with dose from 2.51 to 14.3 L/h. The apparent steady-state volume of distribution (V(ss)) increased with dose from 380 to 1540 L. Renal excretion of the unchanged parent compound increased with increasing plasma concentrations from 2.72% in the 0.5 mg dose group to 23.0% in the 10 mg dose group. The terminal elimination half-life was comparable across dose groups (126-139 hours). Because of the nonlinear pharmacokinetics, the standard approach of comparing the area under the plasma concentration-time curve (AUC) after oral administration with the AUC after intravenous administration led to dose-dependent estimates of the absolute bioavailability. Therefore, a population pharmacokinetic model was developed, accounting for the concentration-dependent protein binding of linagliptin to its target enzyme, DPP-4. The model-derived estimates of the V(ss) and clearance of linagliptin not bound to DPP-4 were 402.2 L and 26.9 L/h, respectively. The absolute bioavailability was estimated to be about 30% for the linagliptin 10 mg tablet. The nonlinear pharmacokinetic characteristics and the pharmacokinetic/pharmacodynamic relationship of linagliptin were independent of the mode of administration (intravenous or oral). Because of the nonlinear pharmacokinetics, the standard approach of comparing the AUC after oral administration with the AUC after intravenous administration was inappropriate to determine the absolute bioavailability of linagliptin. By a modelling approach, the absolute bioavailability of the 10 mg linagliptin tablet was estimated to be about 30%.
    Clinical Pharmacokinetics 12/2010; 49(12):829-40. · 5.40 Impact Factor
  • Article: Impact of target-mediated drug disposition on Linagliptin pharmacokinetics and DPP-4 inhibition in type 2 diabetic patients.
    [show abstract] [hide abstract]
    ABSTRACT: The pharmacokinetics of the novel dipeptidyl-peptidase 4 (DPP-4) inhibitor linagliptin is nonlinear. Based on in vitro experiments, concentration-dependent binding to DPP-4 is the most likely cause for the nonlinearity. Population pharmacokinetic/pharmacodynamic modeling was performed using linagliptin plasma concentrations and plasma DPP-4 activities from 2 phase 2a studies. In these studies, type 2 diabetic patients received either 1, 2.5, 5, or 10 mg of linagliptin once daily over 12 days (study 1) or 2.5, 5, or 10 mg of linagliptin once daily over 28 days (study 2). The modeling results supported the hypothesis that linagliptin exhibits target-mediated drug disposition. The linagliptin plasma concentrations were best described by a 2-compartment model including concentration-dependent protein binding in the central and peripheral compartment. The plasma DPP-4 activity was included in the model in a semi-mechanistic way by relating it to the model-calculated plasma DPP-4 occupancy with linagliptin. The target binding has a major impact on linagliptin pharmacokinetics. Although unbound linagliptin is cleared efficiently (CL/F 220 L/h), the concentration-dependent binding is responsible for the long terminal half-life (approximatelly 120 hours) of linagliptin and its nonlinear pharmacokinetics. The model allowed a comprehensive understanding of the impact of target-mediated drug disposition and provides a useful tool to support clinical development.
    The Journal of Clinical Pharmacology 02/2010; 50(8):873-85. · 2.91 Impact Factor
  • Article: Binding to dipeptidyl peptidase-4 determines the disposition of linagliptin (BI 1356)--investigations in DPP-4 deficient and wildtype rats.
    [show abstract] [hide abstract]
    ABSTRACT: Linagliptin (BI 1356) is a novel dipeptidyl peptidase-4 (DPP-4) inhibitor in clinical development for the treatment of type 2 diabetes. It exhibits non-linear pharmacokinetics and shows concentration-dependent plasma protein binding to its target, DPP-4. The aim of this study was to investigate the impact of saturable binding of linagliptin to plasma and tissue DPP-4 by comparing the pharmacokinetics of linagliptin in wildtype and DPP-4 deficient Fischer rats using non-compartmental and model-based data analysis. The non-compartmental analysis revealed a significantly reduced AUC in DPP-4 deficient rats compared with wildtype rats when single intravenous doses <or=1 mg/kg were administered, but the exposure was similar in both strains at higher doses. The terminal half-lives were significantly shorter in DPP-4 deficient rats compared with wildtype rats. For doses <or=1 mg/kg, DPP-4 deficient rats exhibited linear pharmacokinetics, whereas the pharmacokinetics of wildtype rats was non-linear. In the model-based analysis these differences could be accounted for by assuming concentration-dependent protein binding in the central and one peripheral compartment in wildtype rats. In the model, disposition parameters for unbound linagliptin were assumed to be identical in both rat strains. Simulations with different doses of linagliptin and different concentrations of binding sites further illustrated that the interdependence of linagliptin and DPP-4 in plasma and in the periphery has a major influence on the disposition of linagliptin in wildtype rats. In conclusion, the study showed that the concentration-dependent binding of linagliptin to its target DPP-4 has a major impact on the plasma pharmacokinetics of linagliptin.
    Biopharmaceutics & Drug Disposition 09/2009; 30(8):422-36. · 2.07 Impact Factor