1.
Boger, Elin, et al.
(författare)
A Novel In Vivo Receptor Occupancy Methodology for the Glucocorticoid Receptor : Toward An Improved Understanding of Lung Pharmacokinetic/Pharmacodynamic Relationships
2015
Ingår i: Journal of Pharmacology and Experimental Therapeutics. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0022-3565 .- 1521-0103. ; 353:2, s. 279-287
Tidskriftsartikel (refereegranskat) abstract
Investigation of pharmacokinetic/pharmacodynamic (PK/PD) relationships for inhaled drugs is challenging because of the limited possibilities of measuring tissue exposure and target engagement in the lung. The aim of this study was to develop a methodology for measuring receptor occupancy in vivo in the rat for the glucocorticoid receptor (GR) to allow more informative inhalation PK/PD studies. From AstraZeneca's chemical library of GR binders, compound 1 [N-(2-amino-2-oxo-ethyl)-3-[5-[(1R,2S)-2-(2,2-difluoropropanoylamino)-1-(2,3-dihydro-1,4-benzodioxin-6-yl) propoxy] indazol-1-yl]-N-methyl-benzamide] was identified to have properties that are useful as a tracer for GR in vitro. When given at an appropriate dose (30 nmol/kg) to rats, compound 1 functioned as a tracer in the lung and spleen in vivo using liquid chromatography-tandem mass spectrometry bioanalysis. The methodology was successfully used to show the dose-receptor occupancy relationship measured at 1.5 hours after intravenous administration of fluticasone propionate (20, 150, and 750 nmol/kg) as well as to characterize the time profile for receptor occupancy after a dose of 90 nmol/kg i.v. The dose giving 50% occupancy was estimated as 47 nmol/kg. The methodology is novel in terms of measuring occupancy strictly in vivo and by using an unlabeled tracer. This feature confers key advantages, including occupancy estimation not being influenced by drug particle dissolution or binding/dissociation taking place postmortem. In addition, the tracer may be labeled for use in positron emission tomography imaging, thus enabling occupancy estimation in humans as a translatable biomarker of target engagement.
2.
Fridén, Markus, 1978-
(författare)
Development of Methods for Assessing Unbound Drug Exposure in the Brain : In vivo, in vitro and in silico
2010
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
The blood-brain barrier is formed by tightly joined capillary cells with transporter proteins and acts as to regulate the brain concentration of nutrients as well as many drugs. When developing central nervous system drugs it is necessary to measure the unbound drug concentration in the brain, i.e. the unbound brain exposure. This is to ensure that the drug reaches the site of action. Furthermore, when designing new drugs it is extremely valuable to be able to predict brain exposure from a tentative drug structure. Established methods to measure total drug concentrations are of limited (if any) utility since the pharmacologically active, unbound, concentration is not obtained. The aim of the conducted research was to develop an efficient methodology to measure unbound drug in the brain and to generate a dataset for developing computational prediction models describing the relationship between drug structure and unbound brain exposure. First it was demonstrated that unbound brain exposure can be efficiently assessed using a combination of total drug concentrations in the brain and separate measurements of drug binding in the brain slices. The in vitro brain slice method was refined and made high-throughput. Improvements were also made to the in vivo measurements of total concentrations by introducing an appropriate correction for drug in residual blood. Modeling of a 43-drug dataset in the rat showed that unbound brain exposure is related to the drug hydrogen bonding potential and not to lipid solubility, which contrasts the common understanding. Further, the drug concentrations in cerebrospinal fluid approximated unbound concentrations in the brain (r2=0.80) and were also correlated with corresponding measurements in humans (r2=0.56). Therefore, rat-derived prediction models can be used when designing drugs for humans. This thesis work has provided drug industry and academia with efficient tools to obtain and to use relevant estimates of drug exposure in the brain for evaluating drugs candidates.
3.
Sadiq, Muhammad Waqas, et al.
(författare)
Lung pharmacokinetics of inhaled and systemic drugs : A clinical evaluation
2021
Ingår i: British Journal of Pharmacology. - : John Wiley & Sons. - 0007-1188 .- 1476-5381. ; 178:22, s. 4440-4451
Tidskriftsartikel (refereegranskat) abstract
Background and Purpose Human pharmacokinetic studies of lung-targeted drugs are typically limited to measurements of systemic plasma concentrations, which provide no direct information on lung target-site concentrations. We aimed to evaluate lung pharmacokinetics of commonly prescribed drugs by sampling different lung compartments after inhalation and oral administration. Experimental Approach Healthy volunteers received single, sequential doses of either inhaled salbutamol, salmeterol and fluticasone propionate (n = 12), or oral salbutamol and propranolol (n = 6). Each participant underwent bronchoscopies and gave breath samples for analysis of particles in exhaled air at two points after drug administration (1 and 6, 2 and 9, 3 and 12, or 4 and 18 h). Lung samples were taken via bronchosorption, bronchial brush, mucosal biopsy and bronchoalveolar lavage during each bronchoscopy. Blood samples were taken during the 24 h after administration. Pharmacokinetic profiles were generated by combining data from multiple individuals, covering all sample timings. Key Results Pharmacokinetic profiles were obtained for each drug in lung epithelial lining fluid, lung tissue and plasma. Inhalation of salbutamol resulted in approximately 100-fold higher concentrations in lung than in plasma. Salmeterol and fluticasone concentration ratios in lung versus plasma were higher still. Bronchosorption- and bronchoalveolar-lavage-generated profiles of inhaled drugs in epithelial lining fluid were comparable. For orally administered drugs, epithelial-lining-fluid concentrations were overestimated in bronchoalveolar-lavage-generated profiles. Conclusion and Implications Combining pharmacokinetic data derived from several individuals and techniques sampling different lung compartments enabled generation of pharmacokinetic profiles for evaluation of lung targeting after inhaled and oral drug delivery.
4.
5.
Boger, Elin, et al.
(författare)
Physiologically Based Pharmacokinetic/Pharmacodynamic Modeling Accurately Predicts the Better Bronchodilatory Effect of Inhaled Versus Oral Salbutamol Dosage Forms
2018
Ingår i: Journal of Aerosol Medicine. - : MARY ANN LIEBERT, INC. - 1941-2711 .- 1941-2703. ; 31:0, s. 1-12
Tidskriftsartikel (refereegranskat) abstract
Background: Predicting local lung tissue pharmacodynamic (PD) responses of inhaled drugs is a longstanding challenge related to the lack of experimental techniques to determine local free drug concentrations. This has prompted the use of physiologically based pharmacokinetic (PBPK) modeling to potentially predict local concentration and response. A unique opportunity for PBPK model evaluation is provided by the clinical PD data for salbutamol, which in its inhaled dosage form (400g), produces a higher bronchodilatory effect than in its oral dosage form (2mg) despite lower drug concentrations in blood. The present study aimed at evaluating whether inhalation PBPK model predictions of free drug in tissue would be predictive of these observations.Methods: A PBPK model, including 24 airway generations, was parameterized to describe lung, plasma, and epithelial lining fluid concentrations of salbutamol administered intratracheally and intravenously to rats (100nmol/kg). Plasma and lung tissue concentrations of unbound (R)-salbutamol, the active enantiomer, were predicted with a humanized version of the model and related to effect in terms of forced expiratory volume in 1 second (FEV1).Results: In contrast to oral dosing, the model predicted inhalation to result in spatial heterogeneity in the target site concentrations (subepithelium) with higher free drug concentrations in the lung as compared with the plasma. FEV1 of inhaled salbutamol was accurately predicted from the PK/PD relationship derived from oral salbutamol and PBPK predictions of free concentration in airway tissue of high resistance (e.g., 6th generation).Conclusion: An inhalation PBPK-PD model was developed and shown predictive of local pharmacology of inhaled salbutamol, thus conceptually demonstrating the validity of PBPK model predictions of free drug concentrations in lung tissue. This achievement unlocks the power of inhalation PBPK modeling to interrogate local pharmacology and guide optimization and development of inhaled drugs and their formulations.
6.
Bäckström, Erica, et al.
(författare)
Development of a Novel Lung Slice Methodology for Profiling of Inhaled Compounds
2016
Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0022-3549 .- 1520-6017. ; 105:2, s. 838-845
Tidskriftsartikel (refereegranskat) abstract
The challenge of defining the concentration of unbound drug at the lung target site after inhalation limits the possibility to optimize target exposure by compound design. In this study, a novel rat lung slice methodology has been developed and applied to study drug uptake in lung tissue, and the mechanisms by which this occurs. Freshly prepared lung slices (500 μm) from drug-naive rats were incubated with drugs followed by determination of the unbound drug volume of distribution in lung (Vu,lung), as the total concentration of drug in slices divided by the buffer (unbound) concentration. Vu,lung determined for a set of inhaled drug compounds ranged from 2.21 mL/g for salbutamol to 2970 mL/g for dibasic compound A. Co-incubation with monensin, a modulator of lysosomal pH, resulted in inhibition of tissue uptake of basic propranolol to 13%, indicating extensive lysosomal trapping. Partitioning into cells was particularly high for the cation MPP+ and the dibasic compound A, likely because of the carrier-mediated transport and lysosomal trapping. The results show that different factors are important for tissue uptake and the presented method can be used for profiling of inhaled compounds, leading to a greater understanding of distribution and exposure of drug in the lung.
7.
Bäckström, Erica, et al.
(författare)
Lung Retention by Lysosomal Trapping of Inhaled Drugs Can Be Predicted In Vitro With Lung Slices
2016
Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0022-3549 .- 1520-6017. ; 105:11, s. 3432-3439
Tidskriftsartikel (refereegranskat) abstract
Modulating and optimizing the local pharmacokinetics of inhaled drugs by chemical design or formulation is challenged by the lack of predictive in vitro systems and in vivo techniques providing a detailed description of drug location in the lung. The present study investigated whether a new experimental setup of freshly prepared agarose-filled lung slices can be used to estimate lung retention in vitro, by comparing with in vivo lung retention after intratracheal instillation. Slices preloaded with inhaled beta-adrenergic compounds (salbutamol, formoterol, salmeterol, indacaterol or AZD3199) were incubated in a large volume of buffer (w/wo monensin to assess the role of lysosomal trapping), and the amount remaining in slices at different time points was determined with liquid chromatography-tandem mass spectrometry. The in vitro lung retention closely matched the in vivo lung retention (half-lives within 3-fold for 4/5 compounds), and monensin shortened the half-lives for all compounds. The results suggest that freshly prepared rat lungs slices can be used to predict lung retention and that slow kinetics of lysosomal trapping is a key mechanism by which retention in the lung and the effect duration of inhaled beta-adrenergic bronchodilators are prolonged.
8.
Chen, Hongming, et al.
(författare)
In silico prediction of unbound brain-to-plasma concentration ratio using machine learning algorithms
2011
Ingår i: Journal of Molecular Graphics and Modelling. - : Elsevier BV. - 1093-3263 .- 1873-4243. ; 29:8, s. 985-995
Tidskriftsartikel (refereegranskat) abstract
Distribution over the blood-brain barrier (BBB) is an important parameter to consider for compounds that will be synthesized in a drug discovery project. Drugs that aim at targets in the central nervous system (CNS) must pass the BBB. In contrast, drugs that act peripherally are often optimised to minimize the risk of CNS side effects by restricting their potential to reach the brain. Historically, most prediction methods have focused on the total compound distribution between the blood plasma and the brain. However, recently it has been proposed that the unbound brain-to-plasma concentration ratio (K(p,uu,brain)) is more relevant. In the current study, quantitative K(p,uu,brain) prediction models have been built on a set of 173 in-house compounds by using various machine learning algorithms. The best model was shown to be reasonably predictive for the test set of 73 compounds (R(2) = 0.58). When used for qualitative prediction the model shows an accuracy of 0.85 (Kappa = 0.68). An additional external test set containing 111 marketed CNS active drugs was also classified with the model and 89% of these drugs were correctly predicted as having high brain exposure.
9.
Colcloughl, Nicola, et al.
(författare)
Building on the success of osimertinib : achieving CNS exposure in oncology drug discovery
2019
Ingår i: Drug Discovery Today. - : Elsevier BV. - 1359-6446 .- 1878-5832. ; 24:5, s. 1067-1073
Forskningsöversikt (refereegranskat) abstract
Due to the blood-brain barrier (BBB) limiting the exposure of therapeutics to the central nervous system (CNS), patients with brain malignancies are challenging to treat, typically have poor prognoses, and represent a significant unmet medical need. Preclinical data report osimertinib to have significant BBB penetration and emerging clinical data demonstrate encouraging activity against CNS malignancies. Here, we discuss the oncology drug candidates AZD3759 and AZD1390 as case examples of discovery projects designing in BBB penetrance. We demonstrate how these innovative kinase inhibitors were recognized as brain penetrant and outline our view of experimental approaches and strategies that can facilitate the discovery of new brain-penetrant therapies for the treatment of primary and secondary CNS malignancies as well as other CNS disorders.
10.
Ehrhardt, Carsten, et al.
(författare)
Current Progress Toward a Better Understanding of Drug Disposition Within the Lungs : Summary Proceedings of the First Workshop on Drug Transporters in the Lungs
2017
Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0022-3549 .- 1520-6017. ; 106:9, s. 2234-2244
Tidskriftsartikel (refereegranskat) abstract
The School of Pharmacy and Pharmaceutical Sciences at Trinity College Dublin hosted the "1st Workshop on Drug Transporters in the Lungs" in September 2016 to discuss the impact of transporters on pulmonary drug disposition and their roles as drug targets in lung disease. The workshop brought together about 30 scientists from academia and pharmaceutical industry from Europe and Japan and addressed the primary questions: What do we know today, and what do we need to know tomorrow about transporters in the lung? The 3 themes of the workshop were: (1) techniques to study drug transporter expression and actions in the lungs; (2) drug transporter effects on pulmonary pharmacokinetics-case studies; and (3) transporters as drug targets in lung disease. Some of the conclusions of the workshop were: suitable experimental models that allow studies of transporter effects are available; data from these models convincingly show a contribution of both uptake and efflux transporters on pulmonary drug disposition; the effects of transporters on drug lung PK is now better conceptualized; some transporters are associated with lung diseases. However, more work is needed to establish which of the available models best translate to the clinical situation.
