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Abstract Background and objective: Dabigatran is a new oral anticoagulant recently approved for the prevention of stroke or systemic embolism in patients with atrial fibrillation (AF). Based on its pharmacokinetic profile, dabigatran is dosed twice daily. This analysis provides a quantitative rationale for the selection of the dose regimen in this population. Methods: The pharmacokinetic profile of dabigatran was simulated for AF patients given a total daily dose of 300 mg, either once or twice daily. Simulations were based on a population pharmacokinetic model supplemented with data collected from 9522 patients enrolled in a pivotal phase III study (RE-LY). Results: The typical RE-LY patient (male, 72 years old, Caucasian, weight 80 kg, creatinine clearance 68.64 mL/min) treated with dabigatran 150 mg twice daily showed less than two-fold difference between peak-trough plasma levels compared with a five-fold difference when the same total dose (300 mg) was administered once daily. For patients who miss or delay taking one scheduled dabigatran dose, twice daily dosing maintained adequate minimum trough concentrations better than once daily dosing. Pharmacokinetic data collected from a phase II study and RE-LY were consistent with the simulation results. The study did not access comparative efficacy and bleeding data for once versus twice daily dosing. Conclusion: Pharmacokinetic simulations show that a twice daily regimen in patients with AF minimizes daily fluctuations in plasma concentrations of dabigatran and can maintain trough concentrations sufficient to prevent the development of thrombi while at the same time minimizing the risk of bleeding due to supratherapeutic peak plasma concentrations. The efficacy and safety of this dosing regimen is supported by clinical data from the RE-LY trial. [ABSTRACT FROM AUTHOR]

The 2022 United States Food and Drug Administration (US FDA) draft guidance on diversity plan (DP), which will be implemented through the Diversity Action Plans by December 2025, under the 21st Century Cures Act, marks a pivotal effort by the FDA to ensure that registrational studies adequately reflect the target patient populations based on diversity in demographics and baseline characteristics. This white paper represents the culminated efforts of the International Consortium of Quality and Innovation (IQ) Diversity and Inclusion (D&I) Working Group (WG) to assess the implementation of the draft FDA guidance by members of the IQ consortium in the discipline of clinical pharmacology (CP). This article describes current practices in the industry and emphasizes the tools and techniques of quantitative pharmacology that can be applied to support the inclusion of a diverse population during global drug development, to support diversity and inclusion of underrepresented patient populations, in multiregional clinical trials (MRCTs). It outlines strategic and technical recommendations to integrate demographics, including age, sex/gender, race/ethnicity, and comorbidities, in multiregional phase III registrational studies, through the application of quantitative pharmacology. Finally, this article discusses the challenges faced during global drug development, which may otherwise limit the enrollment of a broader, potentially diverse population in registrational trials. Based on the outcomes of the IQ survey that provided the current awareness of diversity planning, it is envisioned that in the future, industry efforts in the inclusion of previously underrepresented populations during global drug development will culminate in drug labels that apply to the intended patient populations at the time of new drug application or biologics license application rather than through post-marketing requirements., (© 2024 The Author(s). Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Aims: The aim of this work is to compare empagliflozin systemic exposure between patients with heart failure (HF) and patients with type 2 diabetes (T2D)., Methods: Analysis of covariance (ANCOVA) compared steady state trough concentrations of empagliflozin 10 mg in EMPEROR-reduced (patients with HF with reduced ejection fraction [HFrEF]) and EMPA-REG OUTCOME (patients with T2D at high cardiovascular risk) after adjusting for eGFR and body weight., Results: The difference in geometric Mean (gMean) empagliflozin steady state trough concentration of 10 mg empagliflozin between EMPEROR-reduced and EMPA-REG OUTCOME was 1.47-fold (95% confidence interval [CI]: 1.33, 1.63). Additionally, ANCOVA for the sub-group of patients with both T2D and HF conditions revealed a difference in gMean steady state trough concentration of 1.53-fold (95% CI: 1.26, 1.85). In both patients with HFrEF and HF with preserved EF (HFpEF), there was no major difference in empagliflozin steady state trough exposure by New York Heart Association (NYHA) classification or by use of angiotensin receptor-neprilysin inhibitor as comedication. A weak positive correlation was observed for NT-proBNP at Week 12 and empagliflozin steady state trough concentration in both patients with HFrEF and HFpEF (Pearson correlation r = 0.19)., Conclusions: Plasma concentrations of empagliflozin in patients with HF were higher compared to patients with T2D, but the exposure resulting from the 10 mg dose was still below the exposure resulting from the dose of 25 mg approved in patients with T2D. The difference in exposure was attributable to demographic characteristics and HF-induced pathophysiological changes. Overall, the results confirm 10 mg as the appropriate empagliflozin dose in patients with HF., (© 2024 Boehringer Ingelheim Pharma GmbH & Co. KG. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Changes that accompany older age can alter the pharmacokinetics (PK), pharmacodynamics (PD), and likelihood of adverse effects (AEs) of a drug. However, older adults, especially the oldest or those with multiple chronic health conditions, polypharmacy, or frailty, are often under-represented in clinical trials of new drugs. Deficits in the current conduct of clinical evaluation of drugs for older adults and potential steps to fill those knowledge gaps are presented in this communication. The most important step is to increase clinical trial enrollment of older adults who are representative of the target treatment population. Unnecessary eligibility criteria should be eliminated. Physical and financial barriers to participation should be removed. Incentives could be created for inclusion of older adults. Enrollment goals should be established based on intended treatment indications, prevalence of the condition, and feasibility. Relevant clinical pharmacology data need to be obtained early enough to guide dosing and reduce risk for participation of older adults. Relevant PK and PD data as well as patient-centered outcomes should be measured during trials. Trial data should be analyzed for differences in PK, PD, effectiveness, and safety arising from differences in age or from the presence of conditions common in older adults. Postmarket evaluations with real-world evidence and drug labeling updates throughout the product lifecycle reflecting new knowledge are also needed. A comprehensive plan is needed to ensure adequate evaluation of the safety and effectiveness of drugs in older adults., (© 2021 The Authors. Clinical Pharmacology & Therapeutics © 2021 American Society for Clinical Pharmacology and Therapeutics.)

An IQ consortium working group (WG) conducted a survey across multiple biopharmaceutical companies to gain information about the level of blinding commonly utilized for early clinical development trials. The main objectives were: (1) to understand blinding practices between healthy volunteer (HV) and early explorative patient trials in all therapeutic areas except oncology where early clinical trials are commonly open-label; (2) to understand the rationale for blinding/unblinding practices; (3) to understand the groups and personnel involved in unblinding; and (4) strategic considerations around blinding/unblinding options in early clinical development trials-risk of bias vs. potential for acceleration. A survey containing 31 main questions with additional sub-clarifying questions was conducted. Sixteen large and mid-size pharmaceutical companies responded. Responses were aligned across functions within each participating company. Additional information was gathered at an American Association of Pharmaceutical Scientists (AAPS) webinar with polling options to roughly 550 registered attendees to evaluate the reason for the unblinding decisions. The results revealed divergence across companies in the blinding approaches most commonly applied but with some study types, there were clearly favored options. Based on these results, the WG developed strategic considerations for first-in-human HV trials and nonpivotal explorative trials in patients. This paper should facilitate discussions among various clinical development functions, such as Clinical Pharmacology, Statistics, Clinical, Bioanalytics, and Regulatory Functions. Such discussions on study design and operations are warranted to allow implementation of more flexible blinding approaches to accelerate data driven decisions in drug development and allow earlier access of patients to needful medicines., (© 2021 The Authors. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Background: Pediatric regulations enacted in both Europe and the USA have disrupted the pharmaceutical industry, challenging business and drug development processes, and organizational structures. Over the last decade, with science and innovation evolving, industry has moved from a reactive to a proactive mode, investing in building appropriate structures and capabilities as part of their business strategy to better tackle the challenges and opportunities of pediatric drug development., Methods: The EFGCP Children's Medicines Working Party and the IQ Pediatric working group have joined their efforts to survey their member company representatives to understand how pharmaceutical companies are organized to fulfill their regulatory obligations and optimize their pediatric drug development programs., Results: Key success factors and recommendations for a fit-for-purpose Pediatric Expert Group (PEG) were identified., Conclusion: Pediatric structures and expert groups were shown to be important to support optimization of the development of pediatric medicines.

Extrapolation from adults to youth with type 2 diabetes (T2D) is challenged by differences in disease progression and manifestation. This manuscript presents the results of a mock-team workshop focused on examining the typical team-based decision process used to propose a pediatric development plan for T2D addressing the viability of extrapolation. The workshop was held at the American Society for Clinical Pharmacology and Therapeutics (ASCPT) in Orlando, Florida on March 21, 2018., (© 2020 The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals, Inc. on behalf of American Society for Clinical Pharmacology and Therapeutics.)

In October 2016, the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) ICH began efforts to provide recommendations to harmonize guidances for biopharmaceutics classification system (BCS)-based biowaivers. Topics to be addressed included consideration of the dose used to classify solubility, tests, and criteria for establishing highly permeable, dissolution conditions, the influence of excipients, and aspects of product strength. The International Consortium for Innovation and Quality in Pharmaceutical Development (IQ) is a technically focused organization of pharmaceutical and biotechnology companies with a mission of advancing science and technology to augment the capability of member companies to develop transformational solutions that benefit patients, regulators, and the broader R&D community. Its members have substantial expertise in all scientific domains associated with BCS-based waivers and drug product quality, as well as considerable experience in the application of BCS-based biowaivers. The ICH process recognizes that harmonization is achieved through the development of guidelines via a process of scientific consensus with regulatory and industry experts working side-by-side. Thus, to facilitate these efforts and to encourage open and transparent discussion of other perspectives that may exist, IQ offers their perspective on these and related topics.

Extrapolation can be used to address challenges in pediatric drug development. This review describes how these challenges could be addressed by further evolution of quantitative frameworks (i.e., model-based/informed drug discovery and development) and regulatory science in support of pediatric drug development. Included are examples of diseases/indications where extrapolation has been used in different ways as a basis for identifying gaps in the framework and opportunities for continued advancement of pediatric drug development., (© 2017 American Society for Clinical Pharmacology and Therapeutics.)

Faldaprevir (FDV) is a potent, orally administered inhibitor of hepatitis C virus protease. It inhibits multiple cytochrome P-450 enzymes and multiple membrane transporters. The objective of this study was to evaluate the effect of steady-state faldaprevir on the pharmacokinetics (PK) of a single dose of atorvastatin or rosuvastatin. In this single-center, open-label, fixed-sequence crossover study, 33 healthy adult male and female volunteers were given either atorvastatin 10 mg (n = 16) or rosuvastatin 10 mg (n = 17) on day 1. Subjects subsequently received 240 mg twice daily of faldaprevir (loading dose) on day 5, followed by 240 mg faldaprevir once daily from day 6 to day 10, with an additional single dose of atorvastatin (10 mg) or rosuvastatin (10 mg) given on day 10. PK samples for the statins were collected on days 1-3 and days 10-12. Concomitant administration with faldaprevir led to approximately 9-fold and 34-fold increases in AUC 0-∞ and C max , respectively, of atorvastatin and approximately 15-fold and 33-fold increases in AUC 0-∞ and C max , respectively, of rosuvastatin, compared with the statins given alone. Exposure to the major metabolites (ortho-hydroxyatorvastatin and N-desmethylrosuvastatin) was increased to a similar magnitude as that of the parent compounds. The marked drug-drug interaction observed is most likely related to the inhibitory effects of faldaprevir on transporters, particularly hepatic uptake transporters such as OTAP1B1 and OATP1B3. Given the significant increase in exposure to statins in healthy volunteers, coadministration of faldaprevir with statins should be avoided., (© 2017, The American College of Clinical Pharmacology.)

Venous thromboembolism (VTE) incidence is increasing among children owing to many factors, including improved diagnosis of VTE. There is a need for alternative treatment options. Our objective was to investigate the safety, pharmacokinetics (PK) and pharmacodynamics (PD) of dabigatran etexilate in adolescents with VTE. Adolescents aged 12 to <18 years (n = 9) who successfully completed planned treatment for primary VTE were administered dabigatran etexilate twice daily for three days; initially 1.71 (± 10 %) mg/kg (80 % of a 150 mg/70 kg twice daily adult dose), followed by 2.14 (± 10 %) mg/kg (target adult dose adjusted for patient's weight), if there were no safety concerns. No bleeding events, deaths or drug-related serious adverse events (AEs) were reported; three treatment-emergent AEs, all gastrointestinal-related, occurred in two patients. In these adolescent patients with normal renal function, presumed steady-state trough plasma concentrations of dabigatran were low (geometric mean dose-normalised total dabigatran plasma concentration: 0.493 ng/ml/mg at 72 hours). Total dabigatran concentrations were well predicted by the RE-LY® population PK model (94 % of trough concentrations were within the 80 % prediction interval). The relationship between total dabigatran plasma concentration, diluted thrombin time and ecarin clotting time (ECT) was linear; the relationship with activated partial thromboplastin time (aPTT) was non-linear. Adult population PK/PD models predicted the adolescent concentration-ECT and -aPTT relationships well. In conclusion, dabigatran etexilate was generally well tolerated, except for occurrence of dyspepsia in two patients, over the three-day treatment period. The dabigatran PK/PD relationship observed in adolescent patients was similar to that in adult patients.

Background: In adults with moderate renal impairment (creatinine clearance [CrCl] 30-50mL/min) undergoing total hip or knee replacement (THR/TKR), the recommended dose of dabigatran etexilate is 150mg once daily (qd). We investigated the steady state pharmacokinetics, pharmacodynamics and safety in these patients., Methods: Single-arm, open-label phase 4 study (NCT01184989) in Caucasian patients receiving dabigatran etexilate 75mg 1-4h after surgery and 150mg qd on days 2-10 (TKR) or days 2-35 (THR). Plasma total dabigatran concentrations (day 6±1) were determined by high-performance liquid chromatography tandem mass spectrometry and indirectly using the commercially available diluted thrombin time (dTT) assay (Hemoclot® Thrombin Inhibitors)., Results: Of 112 patients (mean CrCl 42.5mL/min, age 79.1years, 69.6% female), 100 completed the study. Geometric mean trough and peak dabigatran concentrations were 47.5ng/mL (10th-90th percentile 19.7-120) and 166ng/mL (49.1-364), respectively. There were four major bleeding events and no venous thromboembolic events. Dabigatran concentrations determined from dTT (and falling within the assay range of 50-500ng/mL) underestimated actual values by 7.6% (90% confidence interval 5.3, 9.9), which is within the acceptance limits of ±15%., Conclusions: These findings in Caucasians with moderate renal impairment undergoing THR or TKR support the use of the 150mg qd dose of dabigatran etexilate. With adequate set-up, calibration and quality control the dTT assay might be appropriate for situations, such as serious bleeding or a need for urgent surgery, where determination of dabigatran levels would be helpful., (Copyright © 2016. Published by Elsevier Ltd.)

Objectives: The goal of this study was to analyze the impact of dabigatran plasma concentrations, patient demographics, and aspirin (ASA) use on frequencies of ischemic strokes/systemic emboli and major bleeds in atrial fibrillation patients., Background: The efficacy and safety of dabigatran etexilate were demonstrated in the RE-LY (Randomized Evaluation of Long-Term Anticoagulation Therapy) trial, but a therapeutic concentration range has not been defined., Methods: In a pre-specified analysis of RE-LY, plasma concentrations of dabigatran were determined in patients treated with dabigatran etexilate 110 mg twice daily (bid) or 150 mg bid and correlated with the clinical outcomes of ischemic stroke/systemic embolism and major bleeding using univariate and multivariate logistic regression and Cox regression models. Patient demographics and ASA use were assessed descriptively and as covariates., Results: Plasma concentrations were obtained from 9,183 patients, with 112 ischemic strokes/systemic emboli (1.3%) and 323 major bleeds (3.8%) recorded. Dabigatran levels were dependent on renal function, age, weight, and female sex, but not ethnicity, geographic region, ASA use, or clopidogrel use. A multiple logistic regression model (c-statistic 0.657, 95% confidence interval [CI]: 0.61 to 0.71) showed that the risk of ischemic events was inversely related to trough dabigatran concentrations (p = 0.045), with age and previous stroke (both p < 0.0001) as significant covariates. Multiple logistic regression (c-statistic 0.715, 95% CI: 0.69 to 0.74) showed major bleeding risk increased with dabigatran exposure (p < 0.0001), age (p < 0.0001), ASA use (p < 0.0003), and diabetes (p = 0.018) as significant covariates., Conclusions: Ischemic stroke and bleeding outcomes were correlated with dabigatran plasma concentrations. Age was the most important covariate. Individual benefit-risk might be improved by tailoring dabigatran dose after considering selected patient characteristics. (Randomized Evaluation of Long Term Anticoagulant Therapy [RE-LY] With Dabigatran Etexilate; NCT00262600)., (Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Fixed-dose unmonitored treatment with dabigatran etexilate is effective and has a favorable safety profile in the prevention of stroke in atrial fibrillation patients compared with warfarin. We hypothesized that genetic variants could contribute to interindividual variability in blood concentrations of the active metabolite of dabigatran etexilate and influence the safety and efficacy of dabigatran., Methods and Results: We successfully conducted a genome-wide association study in 2944 Randomized Evaluation of Long-term Anticoagulation Therapy (RE-LY) participants. The CES1 single-nucleotide polymorphism rs2244613 was associated with trough concentrations, and the ABCB1 single-nucleotide polymorphism rs4148738 and the CES1 single-nucleotide polymorphism rs8192935 were associated with peak concentrations at genome-wide significance (P<9×10(-8)) with a gene-dose effect. Each minor allele of the CES1 single-nucleotide polymorphism rs2244613 was associated with lower trough concentrations (15% decrease per allele; 95% confidence interval, 10-19; P=1.2×10(-8)) and a lower risk of any bleeding (odds ratio, 0.67; 95% confidence interval, 0.55-0.82; P=7×10(-5)) in dabigatran-treated participants, with a consistent but nonsignificant lower risk of major bleeding (odds ratio, 0.66; 95% confidence interval, 0.43-1.01). The interaction between treatment (warfarin versus all dabigatran) and carrier status was statistically significant (P=0.002), with carriers having less bleeding with dabigatran than warfarin (hazard ratio, 0.59; 95% confidence interval, 0.46-0.76; P=5.2×10(-)5) in contrast to no difference in noncarriers (hazard ratio, 0.96; 95% confidence interval, 0.81-1.14; P=0.65). There was no association with ischemic events, and neither rs4148738 nor rs8192935 was associated with bleeding or ischemic events., Conclusions: Genome-wide association analysis identified that carriage of the CES1 rs2244613 minor allele occurred in 32.8% of patients in RE-LY and was associated with lower exposure to active dabigatran metabolite. The presence of the polymorphism was associated with a lower risk of bleeding., Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00262600.

The cytochrome P450 2D6 (CYP2D6) belongs to a group of CYPs considered of utmost importance in the metabolism of xenobiotics. Despite being of only minor abundance in the liver, it is involved in the clearance of >25% of marketed drugs. Accordingly, CYP2D6 can be very efficiently inhibited by a couple of commonly used drugs such as some antidepressants, although induction by any drug has not been observed thus far. CYP2D6 was also one of the first enzymes for which a highly polymorphic expression could be shown leading to a widespread range of functionality, from a complete lack of a functional enzyme to overexpression due to multiplication of active alleles. A clear relationship between the CYP2D6 genotype and adverse events during treatment with CNS-active drugs such as codeine, antidepressants, or antipsychotics could be demonstrated. More recently, some new aspects emerged about the potential endogenous function of CYP2D6 in terms of behavior and brain disorders.

Dabigatran, administered orally as the prodrug dabigatran etexilate (DE), is a direct thrombin inhibitor shown to be effective in the prevention of stroke and systemic embolism in patients with atrial fibrillation (AF). The aim of this analysis was to derive a modeling and simulation-based dose and dosing regimen for AF patients with severe renal failure who could potentially benefit from the use of DE. The exposure was simulated for AF patients with severe renal impairment for several combinations of doses (75, 110, 150 mg) and posologies (BID, QD, Q2D). Simulations were based on a population pharmacokinetic model derived from data from 9522 patients from the pivotal phase III study (RE-LY). Atrial fibrillation patients with a creatinine clearance (CRCL) of <30 to ≥15 mL/min treated with a dose of 75 mg DE BID have target plasma level and exposure data largely within the concentration range proven to be safe and effective in AF patients with CRCL >30 mL/min receiving 150 mg BID. This dosing algorithm was also confirmed and supported by the United States Food and Drug Administration Clinical Pharmacology Division using their model based on the data from the dedicated renal impairment study and taking into account the safety and efficacy information from RE-LY.

Dabigatran etexilate is the orally bioavailable pro-drug of dabigatran, a direct thrombin inhibitor. Using data from eight clinical studies in healthy volunteers and patients with non-valvular atrial fibrillation (AF) or undergoing orthopaedic surgery (OS), population pharmacokinetic (PK) and pharmacodynamic (PD) models were developed to investigate whether the PK and PD of dabigatran differ across different populations. In both healthy volunteers (n=80) and patients (n=1,965), the PK of dabigatran was best described by a two-compartment disposition model with first-order absorption and elimination. Renal function was the only covariate shown to have a clinically relevant impact on dabigatran exposure. The patient PK model was successfully applied in predicting exposure observed in the RE-LY trial evaluating dabigatran treatment in patients with non-valvular AF. The relationship between dabigatran plasma concentrations and activated partial thromboplastin time in healthy volunteers and patients (n=762) was best described with a combination of a linear model and a maximum effect (Emax) model, consistent with previous reports. PK/PD relationships were robust across the various populations tested and were not affected by any of the covariates examined. In summary, the PK of dabigatran is sufficiently consistent to allow extrapolation of data generated in healthy volunteers to patients with AF or undergoing OS.

Objective: To assess the safety, pharmacokinetics (PKs), and blood pressure (BP)-lowering efficacy of telmisartan in pediatric (6 to <18 years) patients with hypertension., Study Design: Patients with diagnosed hypertension were randomized to 4 weeks of treatment with placebo, or with 1 of 2 nominal telmisartan dose levels (1 mg/kg/d or 2 mg/kg/d). The primary end point was change in seated systolic BP (SBP) from baseline to study end., Results: A total of 77 patients were randomized and received at least 1 dose of study medication (placebo, n = 16; low-dose telmisartan, n = 30; high-dose telmisartan, n = 31). Adjusted mean changes (standard errors) in SBP from baseline to study end were -6 (2.4), -14 (1.7), and -9.7 (1.7) mm Hg, respectively, in the placebo, high-dose telmisartan, and low-dose telmisartan groups., Conclusions: Telmisartan may be an appropriate therapy for treatment of pediatric hypertension, although more extensive studies are required in patients younger than age 12.

Dabigatran etexilate is an oral, reversible direct thrombin inhibitor that is approved in the EU and several other countries for the prevention of venous thromboembolism after elective hip and knee replacement, and is in advanced clinical development for other thromboembolic disorders. Dabigatran has a predictable pharmacokinetic profile, allowing for a fixed-dose regimen without the need for routine coagulation monitoring. In certain clinical situations such as serious bleeding into critical organs (e.g. intracerebral bleeding), potential overdose and emergency surgery, clinicians will need to make an assessment of the anticoagulant status of a patient receiving dabigatran before deciding on future management strategies. If available, thrombin clotting time (TT), ecarin clotting time (ECT) and TT determined by Hemoclot thrombin inhibitor assay are sensitive tests to evaluate the anticoagulant effects of dabigatran. Prothrombin time (INR) is less sensitive than other assays and cannot be recommended. The activated partial thromboplastin time (aPTT) can provide a useful qualitative assessment of anticoagulant activity but is less sensitive at supratherapeutic dabigatran levels. There are limited data for activated clotting time (ACT). Overall, the aPTT and TT are the most accessible qualitative methods for determining the presence or absence of anticoagulant effect. Although there is no specific antidote to antagonise the anticoagulant effect of dabigatran, due to its short duration of effect drug discontinuation is usually sufficient to reverse any excessive anticoagulant activity. In case of potential overdose, the feasibility of early administration of activated charcoal and subsequent charcoal filtration are undergoing preclinical evaluation. Dabigatran can also be dialysed in patients with renal impairment. In instances of life-threatening bleeding, where conventional measures have failed or are unavailable, other non-specific prohaemostatic agents such as recombinant activated factor VII and prothrombin complex concentrates can be considered.

Purpose: To establish an in vitro-in vivo level A correlation (IVIVC) for pramipexole slow-release formulations., Methods: The IVIVC was developed based on data from an immediate-release (IR) and three slow-release (SR) formulations of pramipexole; a fourth SR formulation was used for validation purposes. In vitro dissolution profiles were obtained from all SR formulations. Fifteen volunteers received all pramipexole formulations in a randomized cross-over trial. Data were analyzed using the population modelling approach as implemented in NONMEM VI., Results: Dissolution profiles of the SR formulations were described by the Weibull model. The pharmacokinetics of the IR formulation were described by a two-compartment disposition model with first-order absorption. Difference between the in vivo and in vitro estimates of the release rate constants (k(d)) from the Weibull function suggests the release process occurs faster in vivo. Pharmacokinetic profiles for SR formulations were described based on the in vitro release model with k(d) increased in 0.058 h(-1) and the population pharmacokinetic model developed from the IR formulation., Conclusion: A level A IVIVC was established and evaluated for the pramipexole SR formulations, which can be used in the future as a surrogate to avoid certain bioequivalence studies.

Norepinephrine transporter (NET) function has a central role in the regulation of synaptic norepinephrine concentrations. Clinical observations in orthostatic intolerance patients suggest a gender difference in NET function. We compared the cardiovascular response to selective NET inhibition with reboxetine between 12 healthy men and 12 age-matched women. Finger blood pressure, brachial blood pressure, and heart rate were measured. The subjects underwent cardiovascular autonomic reflex testing and a graded head-up tilt test. In a separate study, we applied incremental concentrations of tyramine and isoproterenol through subcutaneous microdialysis catheters in eight men and in eight women. NET inhibition elicited a threefold greater increase in supine blood pressure in men than women (P < 0.05). The pressor response was driven by an increased cardiac output. The orthostatic heart rate increase during NET inhibition was greater in men than women (56 +/- 5 beats/min in men, 42 +/- 4 beats/min in women, P < 0.001). In contrast, NET inhibition resulted in a similar suppression in the cold pressor and handgrip response, low-frequency blood pressure oscillations, and venous norepinephrine in the supine position. Men and women were similarly sensitive to the lipolytic effect of isoproterenol and tyramine. We conclude that NET inhibition results in more pronounced changes in cardiac regulation in men than women. Our observations suggest that the NET contribution to cardiac norepinephrine turnover may be decreased in women. The gender difference in NET function may not be expressed in tissues that are less NET dependent than the heart.