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Weaver E, Macartney RA, Irwin R, Uddin S, Hooker A, Burke GA, Wylie MP, Lamprou DA. Liposomal encapsulation of amoxicillin via microfluidics with subsequent investigation of the significance of PEGylated therapeutics. Int J Pharm 2024; 650:123710. [PMID: 38097147 DOI: 10.1016/j.ijpharm.2023.123710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 12/11/2023] [Accepted: 12/12/2023] [Indexed: 12/19/2023]
Abstract
With an increasing concern of global antimicrobial resistance, the efforts to improve the formulation of a narrowing library of therapeutic antibiotics must be confronted. The liposomal encapsulation of antibiotics using a novel and sustainable microfluidic method has been employed in this study to address this pressing issue, via a targeted, lower-dose medical approach. The study focusses upon microfluidic parameter optimisation, formulation stability, cytotoxicity, and future applications. Particle sizes of circa. 130 nm, with viable short-term (28-day) physical stability were obtained, using two different non-cytotoxic liposomal formulations, both of which displayed suitable antibacterial efficacy. The microfluidic method allowed for high encapsulation efficiencies (≈77 %) and the subsequent in vitro release profile suggested high limits of antibiotic dissociation from the nanovessels, achieving 90% release within 72 h. In addition to the experimental data, the growing use of poly(ethylene) glycol (PEG) within lipid-based formulations is discussed in relation to anti-PEG antibodies, highlighting the key pharmacological differences between PEGylated and non-PEGylated formulations and their respective advantages and drawbacks. It's surmised that in the case of the formulations used in this study, the addition of PEG upon the liposomal membrane would still be a beneficial feature to possess owing to beneficial features such as stability, antibiotic efficacy and the capacity to further modify the liposomal membrane.
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Affiliation(s)
- Edward Weaver
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Robyn A Macartney
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK; Nanotechnology & Integrated Bioengineering Centre (NIBEC), School of Engineering, Ulster University, York Street, Belfast BT15 1ED, UK
| | - Robyn Irwin
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Shahid Uddin
- Immunocore Ltd, 92 Park Dr, Milton, Abingdon OX14 4RY, UK
| | - Andrew Hooker
- Immunocore Ltd, 92 Park Dr, Milton, Abingdon OX14 4RY, UK
| | - George A Burke
- Nanotechnology & Integrated Bioengineering Centre (NIBEC), School of Engineering, Ulster University, York Street, Belfast BT15 1ED, UK
| | - Matthew P Wylie
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Dimitrios A Lamprou
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK.
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2
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Weaver E, Sommonte F, Hooker A, Denora N, Uddin S, Lamprou DA. Microfluidic encapsulation of enzymes and steroids within solid lipid nanoparticles. Drug Deliv Transl Res 2024; 14:266-279. [PMID: 37505373 PMCID: PMC10746583 DOI: 10.1007/s13346-023-01398-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2023] [Indexed: 07/29/2023]
Abstract
The production of solid lipid nanoparticles (SLNs) is challenging, especially when considering the incorporation of biologics. A novel in-house method of microfluidic production of biologic-encapsulated SLNs is proposed, using a variety of base materials for formulation to help overcome the barriers presented during manufacture and administration. Trypsin is used as a model drug for hydrophilic encapsulation whilst testosterone is employed as a positive non-biologic lipophilic control active pharmaceutical ingredient. Particle sizes obtained ranged from 160 to 320 nm, and a lead formulation has been identified from the combinations assayed, allowing for high encapsulation efficiencies (47-90%, respectively) of both the large hydrophilic and the small hydrophobic active pharmaceutical ingredients (APIs). Drug release profiles were analysed in vitro to provide useful insight into sustained kinetics, providing data towards future in vivo studies, which displayed a slow prolonged release for testosterone and a quicker burst release for trypsin. The study represents a large leap forward in the field of SLN production, especially in the field of difficult-to-encapsulate molecules, and the technique also benefits from being more environmentally sustainable due to the use of microfluidics.
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Affiliation(s)
- Edward Weaver
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Federica Sommonte
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
- Department of Pharmacy-Pharmaceutical Sciences, University of Bari "Aldo Moro", 4 Orabona St., Bari, 70125, Italy
| | - Andrew Hooker
- Immunocore Ltd., 92 Park Dr, Milton, Abingdon, OX14 4RY, UK
| | - Nunzio Denora
- Department of Pharmacy-Pharmaceutical Sciences, University of Bari "Aldo Moro", 4 Orabona St., Bari, 70125, Italy
| | - Shahid Uddin
- Immunocore Ltd., 92 Park Dr, Milton, Abingdon, OX14 4RY, UK
| | - Dimitrios A Lamprou
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK.
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3
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Weaver E, Mathew E, Caldwell J, Hooker A, Uddin S, Lamprou DA. The manufacturing of 3D-printed microfluidic chips to analyse the effect upon particle size during the synthesis of lipid nanoparticles. J Pharm Pharmacol 2023; 75:245-252. [PMID: 36453867 DOI: 10.1093/jpp/rgac085] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/26/2022] [Indexed: 12/05/2022]
Abstract
OBJECTIVES The process of 3D printing to produce microfluidic chips is becoming commonplace, due to its quality, versatility and newfound availability. In this study, a UV liquid crystal display (LCD) printer has been implemented to produce a progression of microfluidic chips for the purpose of liposomal synthesis. The emphasis of this research is to test the limitations of UV LCD printing in terms of resolution and print speed optimisation for the production of microfluidic chips. KEY FINDINGS By varying individual channel parameters such as channel length and internal geometries, the essential channel properties for optimal liposomal formulation are being investigated to act as a basis for future experimentation including the encapsulation of active pharmaceutical ingredients. Using the uniquely designed chips, liposomes of ≈120 nm, with polydispersity index values of ≤0.12 are able to be reproducibly synthesised. CONCLUSIONS The influence of total flow rates and lipid choice is investigated in depth, to provide further clarification on how a microfluidic setup should be optimised. In-depth explanations of the importance of each channel parameter are also explained throughout, with reference to their importance for the properties of a successful liposome.
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Affiliation(s)
- Edward Weaver
- School of Pharmacy, Queen's University Belfast, Belfast, UK
| | | | - Jay Caldwell
- School of Pharmacy, Queen's University Belfast, Belfast, UK
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4
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Weaver E, O'Connor E, Cole DK, Hooker A, Uddin S, Lamprou DA. Microfluidic-mediated self-assembly of phospholipids for the delivery of biologic molecules. Int J Pharm 2022; 611:121347. [PMID: 34890709 DOI: 10.1016/j.ijpharm.2021.121347] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/29/2021] [Accepted: 11/30/2021] [Indexed: 12/31/2022]
Abstract
The encapsulation of biologic molecules using a microfluidic platform is a procedure that has been understudied but shows great promise from initial reported studies. The study focusses upon the encapsulation of bovine serum albumin (BSA) under various parameters and using multiple phospholipids to identify optimal conditions for the manufacturing of protein loaded lipid nanoparticles. Additionally, encapsulation of the enzyme trypsin (TRP) has been investigated to show the eligibility of the system to other biological medications. All liposomes were subject to rigorous physicochemical characterisation, including differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR), to document the successful synthesis of the liposomes. Drug-loaded liposome stability was investigated over a 28-day period at 5 °C and 37 °C, which showed encouraging results for 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) at all concentrations of BSA used. The sample containing 1 mg/ml BSA grew by only 10% over the study, which considering liposomes should be affected highly by biologic adsorption, shows great promise for the formulations. Encapsulation and in vitro release studies showed improved loading capacity for BSA compared to conventional methods, whilst maintaining a concise controlled release of the active pharmaceutical ingredient (API).
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Affiliation(s)
- Edward Weaver
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Edward O'Connor
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - David K Cole
- Immunocore, 92 Park Dr, Milton, Abingdon OX14 4RY, UK
| | - Andrew Hooker
- Immunocore, 92 Park Dr, Milton, Abingdon OX14 4RY, UK
| | - Shahid Uddin
- Immunocore, 92 Park Dr, Milton, Abingdon OX14 4RY, UK
| | - Dimitrios A Lamprou
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK.
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Hooker A, Leeuw RA, Twisk J, Brolmann H, Huirne J. O-138 Reproductive performance of women with and without intrauterine adhesions following recurrent dilatation and curettage for miscarriage: long-term follow-up of a randomized controlled trial. Hum Reprod 2021. [DOI: 10.1093/humrep/deab126.069] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Study question
Are the long-term reproductive outcomes following recurrent dilatation and curettage (D&C) for miscarriage in women with identified and treated intrauterine adhesions (IUAs) comparable to women without IUAs.
Summary answer
Reproductive outcomes in women with identified and treated IUAs following recurrent D&C for miscarriage are impaired compared to women without IUAs.
What is known already
The Prevention of Adhesions Post Abortion (PAPA) study showed that application of auto-crosslinked hyaluronic acid (ACP) gel, an absorbable barrier in women undergoing recurrent D&C for miscarriage resulted in a lower rate of IUAs, 13% versus 31% (relative risk 0.43, 95% CI 0.22 to 0.83), lower mean adhesion score and significant less moderate to severe IUAs. It is unclear what the impact is of IUAs on long-term reproductive performance.
Study design, size, duration
This was a follow-up of the PAPA study, a multicenter randomized controlled trial evaluating the application of ACP gel in women undergoing recurrent D&C for miscarriage. All included women received a diagnostic hysteroscopy 8–12 weeks after randomization to evaluate the uterine cavity and for adhesiolysis if IUAs were present. Here, we present the reproductive outcomes in women with identified and treated IUAs versus women without IUAs, 46 months after randomization.
Participants/materials, setting, methods
Between December 2011 and July 2015, 152 women with a first-trimester miscarriage with at least one previous D&C, were randomized for D&C alone or D&C with immediate intrauterine application of ACP gel. Participants were approached at least 30 months after randomization to evaluate reproductive performance, obstetric and neonatal outcomes and cycle characteristics. Main outcome was ongoing pregnancy. Outcomes of subsequent pregnancies, time to conception and time to live birth were also recorded.
Main results and the role of chance
In women pursuing a pregnancy, 14/24 (58%) ongoing pregnancies were recorded in women with identified and treated IUAs versus 80/89 (90%) ongoing pregnancies in women without IUAs odds ratio (OR) 0.18 (95% CI 0.06 to 0.50, P-value <0.001). Documented live birth was also lower in women with IUAs; 13/24 (54%) with versus 75/89 (84%) without IUAs, OR 0.22 (95% CI: 0.08 to-0.59, P-value 0.004). The median time to conception was 7 months in women with identified and treated IUAs versus 5 months in women without IUAs (hazard ratio (HR) 0.84 (95% CI 0.54 to 1.33)) and time to conception leading to a live birth 15 months versus 5.0 months (HR 0.54 (95% CI: 0.30 to 0.97)). In women with identified and treated IUAs, premature deliveries were recorded in 3/16 (19%) versus 4/88 (5%) in women without IUAs, P-value 0.01. Complications were recorded in respectively 12/16 (75%) versus 26/88 (30%), P-value 0.001. No differences were recorded in mean birth weight between the groups.
Limitations, reasons for caution
In the original PAPA study, randomization was applied for ACP gel application. Comparing women with and without IUAs is not in line with the randomization and therefore confounding of the results cannot be excluded. IUAs, if visible during routine hysteroscopy after randomization were removed as part of the study protocol.
Wider implications of the findings
As IUAs have an impact on reproductive performance, even after hysteroscopic adhesiolysis, primary prevention is essential. Expectative and medical management should therefore be considered as serious alternatives for D&C in women with a miscarriage. In case D&C is necessary, application of ACP gel should be considered.
Trial registration number
Netherlands Trial Register NTR 3120.
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Affiliation(s)
- A Hooker
- Zaans Medical Center ZMC, Department of Obstetrics and Gynaecology, Zaandam, The Netherlands
| | - R A Leeuw
- Amsterdam UMC- Location VU University Medical Center- Amsterdam- the Netherlands, Department of Obstetrics and Gynecology, Amsterdam, The Netherlands
| | - J Twisk
- Amsterdam UMC- Location VU University Medical Center- Amsterdam- the Netherlands, Department of Epidemiology and Biostatistics-, Amsterdam, The Netherlands
| | - H Brolmann
- Amsterdam UMC- Location VU University Medical Center- Amsterdam- the Netherlands, Department of Obstetrics and Gynecology, Amsterdam, The Netherlands
| | - J Huirne
- Amsterdam UMC- Location VU University Medical Center- Amsterdam- the Netherlands, Department of Obstetrics and Gynecology, Amsterdam, The Netherlands
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Torres-De La Roche LA, Campo R, Devassy R, Di Spiezio Sardo A, Hooker A, Koninckx P, Urman B, Wallwiener M, De Wilde RL. Adhesions and Anti-Adhesion Systems Highlights. Facts Views Vis Obgyn 2019; 11:137-149. [PMID: 31824635 PMCID: PMC6897521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The peritoneal and intrauterine cavities are lined by fragile membranes with a high-wound healing capacity, e.g. repairing the endometrium in its cyclical "injury and scar-free repair process" during menstruation. However, peritoneal and intrauterine fibrosis and adhesions can develop after surgical trauma through activation of molecular, immune and genetic mechanisms. During procedures with a high-risk of adhesions, the use of new peritoneal and intrauterine conditions in combination with anti-adhesion substances are promising measures to preserve peritoneal and endometrial function and avoid the most common complication of gynecological surgery. Highlights of adhesions and anti-adhesion prevention techniques in laparoscopic, laparotomic and hysteroscopic surgeries are discussed in this paper. Unfortunately, evidence is lacking to prove the superiority of one technique over its counterparts in terms of postoperative adhesions, such as instrumentation, type of energy, distending media, and intracavitary pressure. Additionally, there is limited evidence about the efficacy and outcomes of techniques and adjuvant measures used during adhesiolysis. The definition of a universal intrauterine adhesions classification scheme as well as a prognostic scoring system to identify women at high risk of postoperative adhesions are necessary for advising those who could benefit the most of the use of antiadhesion barriers.
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Affiliation(s)
- LA Torres-De La Roche
- University Hospital for Gynecology, Pius Hospital, University Medicine Oldenburg, Carl von Ossietzky University Oldenburg, 26121, Germany
| | - R Campo
- Leuven Institute for Fertility and Embryology, Tiensevest, 3000, Leuven
| | - R Devassy
- Dubai London Clinic and Speciality Hospital, Dubai, 3371500, UAE
| | | | - A Hooker
- Zaans Medical Centre, Zaandam, 1502, Netherlands
| | - P Koninckx
- UZ Leuven Campus Gasthuisberg, Leuven, 3000, Belgium
| | - B Urman
- Koç University Faculty of Medicine, Department of Obstetrics and Gynecology, Istanbul, Turkey, 34330, Turkey
| | - M Wallwiener
- Heidelberg University Women's Hospital, Heidelberg, 69115, Germany
| | - RL De Wilde
- University Hospital for Gynecology, Pius Hospital, University Medicine Oldenburg, Carl von Ossietzky University Oldenburg, 26121, Germany
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Fang L, Kim MJ, Li Z, Wang Y, DiLiberti CE, Au J, Hooker A, Ducharme MP, Lionberger R, Zhao L. Model-Informed Drug Development and Review for Generic Products: Summary of FDA Public Workshop. Clin Pharmacol Ther 2018; 104:27-30. [PMID: 29603191 DOI: 10.1002/cpt.1065] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 03/05/2018] [Accepted: 03/07/2018] [Indexed: 11/07/2022]
Abstract
On October 2nd and 3rd , 2017, the US Food and Drug Administration (FDA) hosted a public workshop titled "Leveraging Quantitative Methods and Modeling to Modernize Generic Drug Development and Review."1 This report summarizes Session 2 of the public workshop: "Model Informed Drug Development and Review for Generic Products." The session focused on the application of quantitative methods and modeling in modernizing the generic drug development and review.
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Affiliation(s)
- Lanyan Fang
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Myong-Jin Kim
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Zhichuan Li
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Yaning Wang
- Office of Clinical Pharmacology, Office of Translational Sciences, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
| | | | - Jessie Au
- Optimum Therapeutics LLC, Carlsbad, California, USA
| | - Andrew Hooker
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | | | - Robert Lionberger
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Liang Zhao
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
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Abstract
Several software tools are available that facilitate the use of the NONMEM software and extend its functionality. This tutorial shows how three commonly used and freely available tools, Pirana, PsN, and Xpose, form a tightly integrated workbench for modeling and simulation with NONMEM. During the tutorial, we provide some guidance on what diagnostics we consider most useful in pharmacokinetic model development and how to construct them using these tools.
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Affiliation(s)
- R J Keizer
- Department of Pharmaceutical Biosciences, Pharmacometrics research Group, Uppsala University, Uppsala, Sweden
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9
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Mentré F, Chenel M, Comets E, Grevel J, Hooker A, Karlsson MO, Lavielle M, Gueorguieva I. Current Use and Developments Needed for Optimal Design in Pharmacometrics: A Study Performed Among DDMoRe's European Federation of Pharmaceutical Industries and Associations Members. CPT Pharmacometrics Syst Pharmacol 2013; 2:e46. [PMID: 23887744 PMCID: PMC3697035 DOI: 10.1038/psp.2013.19] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 03/13/2013] [Indexed: 01/07/2023]
Affiliation(s)
- F Mentré
- UMR 738, INSERM, University Paris Diderot, Paris, France
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10
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Kumpulainen E, Välitalo P, Kokki M, Lehtonen M, Hooker A, Ranta VP, Kokki H. Plasma and cerebrospinal fluid pharmacokinetics of flurbiprofen in children. Br J Clin Pharmacol 2011; 70:557-66. [PMID: 20840447 DOI: 10.1111/j.1365-2125.2010.03720.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
AIMS This study was designed to characterize paediatric pharmacokinetics and central nervous system exposure of flurbiprofen. METHODS The pharmacokinetics of flurbiprofen were studied in 64 healthy children aged 3 months to 13 years, undergoing surgery with spinal anaesthesia. Children were administered preoperatively a single dose of flurbiprofen intravenously as prodrug (n= 27) or by mouth as syrup (n= 37). A single cerebrospinal fluid (CSF) sample (n= 60) was collected at the induction of anaesthesia, and plasma samples (n= 304) before, during and after the operation (up to 20 h after administration). A population pharmacokinetic model was built using the NONMEM software package. RESULTS Flurbiprofen concentrations in plasma were well described by a three compartment model. The apparent bioavailability of oral flurbiprofen syrup was 81%. The estimated clearance (CL) was 0.96l h(-1) 70 kg(-1) . Age did not affect the clearance after weight had been included as a covariate. The estimated volume of distribution at steady state (V(ss) ) was 8.1 l 70 kg(-1) . Flurbiprofen permeated into the CSF, reaching concentrations that were seven-fold higher compared with unbound plasma concentrations. CONCLUSIONS Flurbiprofen pharmacokinetics can be described using only weight as a covariate in children above 6months, while more research is needed in neonates and in younger infants.
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Affiliation(s)
- Elina Kumpulainen
- Department of Pharmacology and Toxicology, University of Eastern Finland, Kuopio
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Sjögren E, Nyberg J, Magnusson MO, Lennernäs H, Hooker A, Bredberg U. Optimal experimental design for assessment of enzyme kinetics in a drug discovery screening environment. Drug Metab Dispos 2011; 39:858-63. [PMID: 21289074 DOI: 10.1124/dmd.110.037309] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A penalized expectation of determinant (ED)-optimal design with a discrete parameter distribution was used to find an optimal experimental design for assessment of enzyme kinetics in a screening environment. A data set for enzyme kinetic data (V(max) and K(m)) was collected from previously reported studies, and every V(max)/K(m) pair (n = 76) was taken to represent a unique drug compound. The design was restricted to 15 samples, an incubation time of up to 40 min, and starting concentrations (C(0)) for the incubation between 0.01 and 100 μM. The optimization was performed by finding the sample times and C(0) returning the lowest uncertainty (S.E.) of the model parameter estimates. Individual optimal designs, one general optimal design and one, for laboratory practice suitable, pragmatic optimal design (OD) were obtained. In addition, a standard design (STD-D), representing a commonly applied approach for metabolic stability investigations, was constructed. Simulations were performed for OD and STD-D by using the Michaelis-Menten (MM) equation, and enzyme kinetic parameters were estimated with both MM and a monoexponential decay. OD generated a better result (relative standard error) for 99% of the compounds and an equal or better result [(root mean square error (RMSE)] for 78% of the compounds in estimation of metabolic intrinsic clearance. Furthermore, high-quality estimates (RMSE < 30%) of both V(max) and K(m) could be obtained for a considerable number (26%) of the investigated compounds by using the suggested OD. The results presented in this study demonstrate that the output could generally be improved compared with that obtained from the standard approaches used today.
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Affiliation(s)
- Erik Sjögren
- Department of Pharmacy, Uppsala University, Box 580, SE-751 23 Uppsala, Sweden
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12
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Syvänen S, Hooker A, Rahman O, Wilking H, Blomquist G, Långström B, Bergström M, Hammarlund-Udenaes M. Pharmacokinetics of P-glycoprotein inhibition in the rat blood-brain barrier. J Pharm Sci 2009; 97:5386-400. [PMID: 18384156 DOI: 10.1002/jps.21359] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This article describes the experimental set-up and pharmacokinetic modeling of P-glycoprotein function in the rat blood-brain barrier using [(11)C]verapamil as the substrate and cyclosporin A as an inhibitor of P-gp. [(11)C]verapamil was administered to rats as an i.v. bolus dose followed by graded infusions to obtain steady-state concentrations in the brain during 70 min. CsA was administered as a bolus followed by a constant infusion 20 min after the start of the [(11)C]verapamil infusion. The brain uptake of [(11)C]verapamil over 2 h was portrayed in a sequence of PET scans in parallel with measurement of [(11)C]verapamil concentrations in blood and plasma and CsA concentrations in blood. Mixed effects modeling in NONMEM was used to build a pharmacokinetic model of CsA-induced P-gp inhibition. The brain pharmacokinetics of [(11)C]verapamil was well described by a two-compartment model. The effect of CsA on the uptake of [(11)C]verapamil in the brain was best described by an inhibitory indirect effect model with an effect on the transport of [(11)C]verapamil out of the brain. The CsA concentration required to obtain 50% of the maximal inhibition was 4.9 microg/mL (4.1 microM). The model parameters indicated that 93% of the outward transport of [(11)C]verapamil was P-gp mediated.
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Affiliation(s)
- Stina Syvänen
- Department of Pharmaceutical Biosciences, Uppsala University, Box 591, 751 24 Uppsala, Sweden.
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13
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Abstract
Multiple outputs or measurement types are commonly gathered in biological experiments. Often, these experiments are expensive (such as clinical drug trials) or require careful design to achieve the desired information content. Optimal experimental design protocols could help alleviate the cost and increase the accuracy of these experiments. In general, optimal design techniques ignore between-individual variability, but even work that incorporates it (population optimal design) has treated simultaneous multiple output experiments separately by computing the optimal design sequentially, first finding the optimal design for one output (eg, a pharmacokinetic [PK] measurement) and then determining the design for the second output (eg, a pharmacodynamic [PD] measurement). Theoretically, this procedure can lead to biased and imprecise results when the second model parameters are also included in the first model (as in PK-PD models). We present methods and tools for simultaneous population D-optimal experimental designs, which simultaneously compute the design of multiple output experiments, allowing for correlation between model parameters. We then apply these methods to simulated PK-PD experiments. We compare the new simultaneous designs to sequential designs that first compute the PK design, fix the PK parameters, and then compute the PD design in an experiment. We find that both population designs yield similar results in designs for low sample number experiments, with simultaneous designs being possibly superior in situations in which the number of samples is unevenly distributed between outputs. Simultaneous population D-optimality is a potentially useful tool in the emerging field of experimental design.
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Affiliation(s)
- Andrew Hooker
- />Resource Facility for Population Kinetics, Department of Bioengineering, University of Washington, Box 352255, 98195-2255 Seattle, WA
| | - Paolo Vicini
- />Resource Facility for Population Kinetics, Department of Bioengineering, University of Washington, Box 352255, 98195-2255 Seattle, WA
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14
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Keenan TM, Hooker A, Spilker ME, Li N, Boggy GJ, Vicini P, Folch A. Automated identification of axonal growth cones in time-lapse image sequences. J Neurosci Methods 2005; 151:232-8. [PMID: 16174535 PMCID: PMC3848907 DOI: 10.1016/j.jneumeth.2005.07.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2004] [Revised: 06/20/2005] [Accepted: 07/27/2005] [Indexed: 10/25/2022]
Abstract
The isolation and purification of axon guidance molecules has enabled in vitro studies of the effects of axon guidance molecule gradients on numerous neuronal cell types. In a typical experiment, cultured neurons are exposed to a chemotactic gradient and their growth is recorded by manual identification of the axon tip position from two or more micrographs. Detailed and statistically valid quantification of axon growth requires evaluation of a large number of neurons at closely spaced time points (e.g. using a time-lapse microscopy setup). However, manual tracing becomes increasingly impractical for recording axon growth as the number of time points and/or neurons increases. We present a software tool that automatically identifies and records the axon tip position in each phase-contrast image of a time-lapse series with minimal user involvement. The software outputs several quantitative measures of axon growth, and allows users to develop custom measurements. For, example analysis of growth velocity for a dissociated E13 mouse cortical neuron revealed frequent extension and retraction events with an average growth velocity of 0.05 +/- 0.14 microm/min. Comparison of software-identified axon tip positions with manually identified axon tip positions shows that the software's performance is indistinguishable from that of skilled human users.
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Affiliation(s)
| | | | | | | | | | | | - Albert Folch
- Corresponding author. Tel.: +1 206 685 2257; fax: +1 206 616 1984. (A. Folch)
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Foracchia M, Hooker A, Vicini P, Ruggeri A. POPED, a software for optimal experiment design in population kinetics. Comput Methods Programs Biomed 2004; 74:29-46. [PMID: 14992824 DOI: 10.1016/s0169-2607(03)00073-7] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/04/2003] [Indexed: 05/24/2023]
Abstract
Population kinetic analysis is the methodology used to quantify inter-subject variability in kinetic studies. It entails the collection of (possibly sparse) data from dynamic experiments in a group of subjects and their quantitative interpretation by means of a mathematical model. This methodology is widely used in the pharmaceutical industry (where it is termed "pharmacokinetic population analysis") and recently it is becoming increasingly used in other areas of biomedical research. Unlike traditional kinetic studies, where the number of subjects can be quite small, population kinetic studies require large numbers of subjects. It is, therefore, of great interest to design these studies in the most efficient manner possible, to maximize the information content provided by the data. In this paper we propose an algorithm and a computer program, POPED, for the optimal design of a population kinetic experiment. In particular, the number of samples for each subject and the design of the individual sampling strategies, i.e. the number and location of the time points at which the output variable is sampled, will be considered. Among the various criteria proposed in the literature, D and ED optimality are the ones implemented in our software program, since they are the most widely used. A brief description of the techniques employed to perform design optimization is given, together with some details on their actual implementation. Some examples are then presented to show the program usage and the results provided.
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Affiliation(s)
- Marco Foracchia
- Department of Information Engineering, University of Padova, Via Gradenigo 6/a, 35131 Padua, Italy
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Kerwin W, Hooker A, Spilker M, Vicini P, Ferguson M, Hatsukami T, Yuan C. Quantitative magnetic resonance imaging analysis of neovasculature volume in carotid atherosclerotic plaque. Circulation 2003; 107:851-6. [PMID: 12591755 DOI: 10.1161/01.cir.0000048145.52309.31] [Citation(s) in RCA: 293] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Neovasculature within atherosclerotic plaques is believed to be associated with infiltration of inflammatory cells and plaque destabilization. The aim of the present investigation was to determine whether the amount of neovasculature present in advanced carotid plaques can be noninvasively measured by dynamic, contrast-enhanced MRI. METHODS AND RESULTS A total of 20 consecutive patients scheduled for carotid endarterectomy were recruited to participate in an MRI study. Images were obtained at 15-second intervals, and a gadolinium contrast agent was injected coincident with the second of 10 images in the sequence. The resulting image intensity within the plaque was tracked over time, and a kinetic model was used to estimate the fractional blood volume. For validation, matched sections from subsequent endarterectomy were stained with ULEX and CD-31 antibody to highlight microvessels. Finally, all microvessels within the matched sections were identified, and their total area was computed as a fraction of the plaque area. Results were obtained from 16 participants, which showed fractional blood volumes ranging from 2% to 41%. These levels were significantly higher than the histological measurements of fractional vascular area. Nevertheless, the 2 measurements were highly correlated, with a correlation coefficient of 0.80 (P<0.001). CONCLUSIONS Dynamic contrast-enhanced MRI provides an indication of the extent of neovasculature within carotid atherosclerotic plaque. MRI therefore provides a means for prospectively studying the link between neovasculature and plaque vulnerability.
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Affiliation(s)
- William Kerwin
- Department of Radiology, University of Washington, Seattle 98195, USA.
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Abstract
The cloning of the cDNA for human interferon-gamma (IFN-gamma) has resulted in its expression in Escherichia coli, baculovirus-infected insect cells, Chinese hamster ovary (CHO) cells, and the mammary gland of transgenic mice. Large quantities of highly purified recombinant IFN-gamma have been generated, aided by the use of highly specific neutralizing monoclonal antibodies, with a view to its production as a human therapeutic protein. The primary source of structural heterogeneity for IFN-gamma during its production in mammalian expression systems is glycosylation, which can profoundly affect the three-dimensional structure of a glycoprotein and its biological function. A number of analytical approaches have been developed recently to allow a detailed analysis of the carbohydrate structures associated with IFN-gamma, the principal advances being in the areas of capillary electrophoresis and mass spectrometry. The implementation of these high-resolution analytical tools to determine the glycosylation profile of IFN-gamma makes it one of the best characterized recombinant glycoproteins. Recombinant human IFN-gamma acts as a model secretory glycoprotein, typifying the intrinsic glycosylation processing events associated with production of a potential therapeutic glycoprotein.
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Affiliation(s)
- A Hooker
- Oxford GlycoSciences (UK) Plc, Abingdon Science Park, United Kingdom.
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Affiliation(s)
- A R Ready
- Renal Unit, Queen Elizabeth Hospital, Edgbaston, Birmingham, England
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