1.
Alskär, Oskar
(author)
Mechanism-Based Modelling of Clinical and Preclinical Studies of Glucose Homeostasis
2018
Doctoral thesis (other academic/artistic) abstract
Glucose is an important nutrient and energy source in the body. However, too high concentration in the blood is harmful and may lead to several complications developing over time. It was estimated that 5 million people in the world died from complications related to diabetes during 2015. Several hormones and physiological factors are involved in the regulation of glucose homeostasis. To evaluate different aspects of glucose homeostasis and the effect of interventions, such as pharmacological treatment, glucose tolerance tests can be performed. In a glucose tolerance test glucose is administered either orally or intravenously, blood is sampled frequently and analyzed for different biomarkers. Mechanism-based pharmacometric models is a valuable tool in drug development, which can be applied to increase the knowledge about complex systems such as glucose homeostasis, quantify the effects of drugs, generate more information from clinical trials and contribute to more efficient study design. In this thesis, a new comprehensive mechanism-based pharmacometric model was developed. The model is capable of describing the most important aspects of glucose homeostasis during glucose tolerance test in healthy individuals and patients with type 2 diabetes, over a wide range of oral and intravenous glucose doses. Moreover, it can simultaneously describe regulation of gastric emptying and glucose absorption, regulation of the incretin hormones GLP-1 and GIP, hepatic extraction of insulin and the incretin effect, regulation of glucagon synthesis and regulation of endogenous glucose production. In addition, an interspecies scaling approach was developed by scaling a previously developed clinical glucose insulin model to describe intravenous glucose tolerance tests performed in mice, rats, dogs, pigs and monkeys. In conclusion, the developed mechanism-based models in this thesis increases the knowledge about short term regulation of glucose homeostasis and can be used to investigate combination treatments, drugs with multiple effects, and translation of drug effects between species, leading to improved drug development of new antidiabetic compounds.
2.
Bouchene, Salim, 1984-, et al.
(author)
A Whole-Body Physiologically Based Pharmacokinetic Model for Colistin and Colistin Methanesulfonate in Rat
2018
In: Basic & Clinical Pharmacology & Toxicology. - : Wiley. - 1742-7835 .- 1742-7843. ; 123:4, s. 407-422
Journal article (peer-reviewed) abstract
Colistin is a polymyxin antibiotic used to treat patients infected with multidrug-resistant Gram-negative bacteria (MDR-GNB). The objective of this work was to develop a whole-body physiologically based pharmacokinetic (WB-PBPK) model to predict tissue distribution of colistin in rat. The distribution of a drug in a tissue is commonly characterized by its tissue-to-plasma partition coefficient, K-p. Colistin and its prodrug, colistin methanesulfonate (CMS) K-p priors, were measured experimentally from rat tissue homogenates or predicted in silico. The PK parameters of both compounds were estimated fitting invivo their plasma concentration-time profiles from six rats receiving an i.v. bolus of CMS. The variability in the data was quantified by applying a nonlinear mixed effect (NLME) modelling approach. A WB-PBPK model was developed assuming a well-stirred and perfusion-limited distribution in tissue compartments. Prior information on tissue distribution of colistin and CMS was investigated following three scenarios: K-p was estimated using in silico K-p priors (I) or K-p was estimated using experimental K-p priors (II) or K-p was fixed to the experimental values (III). The WB-PBPK model best described colistin and CMS plasma concentration-time profiles in scenario II. Colistin-predicted concentrations in kidneys in scenario II were higher than in other tissues, which was consistent with its large experimental K-p prior. This might be explained by a high affinity of colistin for renal parenchyma and active reabsorption into the proximal tubular cells. In contrast, renal accumulation of colistin was not predicted in scenario I. Colistin and CMS clearance estimates were in agreement with published values. The developed model suggests using experimental priors over in silico K-p priors for kidneys to provide a better prediction of colistin renal distribution. Such models might serve in drug development for interspecies scaling and investigate the impact of disease state on colistin disposition.
3.
Brekkan, Ari, et al.
(author)
A Population Pharmacokinetic-Pharmacodynamic Model of Pegfilgrastim
2018
In: AAPS Journal. - : SPRINGER. - 1550-7416. ; 20:5
Journal article (peer-reviewed) abstract
Neutropenia and febrile neutropenia (FN) are serious side effects of cytotoxic chemotherapy which may be alleviated with the administration of recombinant granulocyte colony-stimulating factor (GCSF) derivatives, such as pegfilgrastim (PG) which increases absolute neutrophil count (ANC). In this work, a population pharmacokinetic-pharmacodynamic (PKPD) model was developed based on data obtained from healthy volunteers receiving multiple administrations of PG. The developed model was a bidirectional PKPD model, where PG stimulated the proliferation, maturation, and margination of neutrophils and where circulating neutrophils in turn increased the elimination of PG. Simulations from the developed model show disproportionate changes in response with changes in dose. A dose increase of 10% from the 6 mg therapeutic dose taken as a reference leads to area under the curve (AUC) increases of similar to 50 and similar to 5% for PK and PD, respectively. A full random effects covariate model showed that little of the parameter variability could be explained by sex, age, body size, and race. As a consequence, little of the secondary parameter variability (C-max and AUC of PG and ANC) could be explained by these covariates.
4.
Garcia-Prats, Anthony J., et al.
(author)
Pharmacokinetics and safety of high-dose rifampicin in children with TB : the Opti-Rif trial
2021
In: Journal of Antimicrobial Chemotherapy. - : Oxford University Press. - 0305-7453 .- 1460-2091. ; 76:12, s. 3237-3246
Journal article (peer-reviewed) abstract
Background: Rifampicin doses of 40 mg/kg in adults are safe and well tolerated, may shorten anti-TB treatment and improve outcomes, but have not been evaluated in children. Objectives: To characterize the pharmacokinetics and safety of high rifampicin doses in children with drug-susceptible TB. Patients and methods: The Opti-Rif trial enrolled dosing cohorts of 20 children aged 0-12 years, with incremental dose escalation with each subsequent cohort, until achievement of target exposures or safety concerns. Cohort 1 opened with a rifampicin dose of 15 mg/kg for 14 days, with a single higher dose (35 mg/kg) on day 15. Pharmacokinetic data from days 14 and 15 were analysed using population modelling and safety data reviewed. Incrementally increased rifampicin doses for the next cohort (days 1-14 and day 15) were simulated from the updated model, up to the dose expected to achieve the target exposure [235 mg/L.h, the geometric mean area under the concentration-time curve from 0 to 24h (AUC(0-24)) among adults receiving a 35mg/kg dose]. Results: Sixty-two children were enrolled in three cohorts. The median age overall was 2.1 years (range=0.4-11.7). Evaluated doses were similar to 35 mg/kg (days 1-14) and similar to 50 mg/kg (day 15) for cohort 2 and similar to 60 mg/kg (days 1-14) and similar to 75mg/kg (day 15) for cohort 3. Approximately half of participants had an adverse event related to study rifampicin; none was grade 3 or higher. A 65-70 mg/kg rifampicin dose was needed in children to reach the target exposure. Conclusions: High rifampicin doses in children achieved target exposures and the doses evaluated were safe over 2 weeks.
5.
Wallin, Johan E., et al.
(author)
A tool for neutrophil guided dose adaptation in chemotherapy
2009
In: Computer Methods and Programs in Biomedicine. - : Elsevier BV. - 0169-2607 .- 1872-7565. ; 93:3, s. 283-291
Journal article (peer-reviewed) abstract
Chemotherapy dosing in anticancer treatment is a balancing act between achieving concentrations that are effective towards the malignancy and that result in acceptable side-effects. Neutropenia is one major side-effect of many antitumor agents, and is related to an increased risk of infection. A model capable of describing the time-course of myelosuppression from administered drug could be used in individual dose selection. In this paper we describe the transfer of a previously developed semi-mechanistic model for myelosuppression from NONMEM to a dosing tool in MS Excel, with etoposide as an example. The tool proved capable to solve a differential equation system describing the pharmacokinetics and pharmacodynamics, with estimation performance comparable to NONMEM. In the dosing tool the user provides neutrophil measures from a previous treatment course and request for the dose that results in a desired nadir in the upcoming course through a Bayesian estimation procedure.
6.
7.
8.
Alskär, Oskar, et al.
(author)
Model-Based Interspecies Scaling of Glucose Homeostasis
2017
In: CPT. - : John Wiley & Sons. - 2163-8306. ; 6:11, s. 778-786
Journal article (peer-reviewed) abstract
Being able to scale preclinical pharmacodynamic response to clinical would be beneficial in drug development. In this work, the integrated glucose insulin (IGI) model, developed on clinical intravenous glucose tolerance test (IVGTT) data, describing dynamic glucose and insulin concentrations during glucose tolerance tests, was scaled to describe data from similar tests performed in healthy rats, mice, dogs, pigs, and humans. Several approaches to scaling the dynamic glucose and insulin were investigated. The theoretical allometric exponents of 0.75 and 1, for clearances and volumes, respectively, could describe the data well with some species-specific adaptations: dogs and pigs showed slower first phase insulin secretion than expected from the scaling, pigs also showed more rapid insulin dependent glucose elimination, and rodents showed differences in glucose effectiveness. The resulting scaled IGI model was shown to accurately predict external preclinical IVGTT data and may be useful in facilitating translations of preclinical research into the clinic.
9.
Back, Hyun-moon, et al.
(author)
A mechanism-based pharmacokinetic model of fenofibrate for explaining increased drug absorption after food consumption
2018
In: BMC Pharmacology & Toxicology. - : BIOMED CENTRAL LTD. - 2050-6511. ; 19
Journal article (peer-reviewed) abstract
Background: Oral administration of drugs is convenient and shows good compliance but it can be affected by many factors in the gastrointestinal (GI) system. Consumption of food is one of the major factors affecting the GI system and consequently the absorption of drugs. The aim of this study was to develop a mechanistic GI absorption model for explaining the effect of food on fenofibrate pharmacokinetics (PK), focusing on the food type and calorie content.Methods: Clinical data from a fenofibrate PK study involving three different conditions (fasting, standard meals and high-fat meals) were used. The model was developed by nonlinear mixed effect modeling method. Both linear and nonlinear effects were evaluated to explain the impact of food intake on drug absorption. Similarly, to explain changes in gastric emptying time for the drug due to food effects was evaluated.Results: The gastric emptying rate increased by 61.7% during the first 6.94 h after food consumption. Increased calories in the duodenum increased the absorption rate constant of the drug in fed conditions (standard meal = 16.5%, high-fat meal = 21.8%) compared with fasted condition. The final model displayed good prediction power and precision.Conclusions: A mechanistic GI absorption model for quantitatively evaluating the effects of food on fenofibrate absorption was successfully developed, and acceptable parameters were obtained. The mechanism-based PK model of fenofibrate can quantify the effects of food on drug absorption by food type and calorie content.
10.
Bonate, Peter L., et al.
(author)
Methods and strategies for assessing uncontrolled drug-drug interactions in population pharmacokinetic analyses : results from the International Society of Pharmacometrics (ISOP) Working Group
2016
In: Journal of Pharmacokinetics and Pharmacodynamics. - : Springer Science and Business Media LLC. - 1567-567X .- 1573-8744. ; 43:2, s. 123-135
Journal article (other academic/artistic) abstract
The purpose of this work was to present a consolidated set of guidelines for the analysis of uncontrolled concomitant medications (ConMed) as a covariate and potential perpetrator in population pharmacokinetic (PopPK) analyses. This white paper is the result of an industry-academia-regulatory collaboration. It is the recommendation of the working group that greater focus be given to the analysis of uncontrolled ConMeds as part of a PopPK analysis of Phase 2/3 data to ensure that the resulting outcome in the PopPK analysis can be viewed as reliable. Other recommendations include: (1) collection of start and stop date and clock time, as well as dose and frequency, in Case Report Forms regarding ConMed administration schedule; (2) prespecification of goals and the methods of analysis, (3) consideration of alternate models, other than the binary covariate model, that might more fully characterize the interaction between perpetrator and victim drug, (4) analysts should consider whether the sample size, not the percent of subjects taking a ConMed, is sufficient to detect a ConMed effect if one is present and to consider the correlation with other covariates when the analysis is conducted, (5) grouping of ConMeds should be based on mechanism (e.g., PGP-inhibitor) and not drug class (e.g., beta-blocker), and (6) when reporting the results in a publication, all details related to the ConMed analysis should be presented allowing the reader to understand the methods and be able to appropriately interpret the results.
