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Article ; Online: Infection prevention and control guidance for Ronald McDonald Houses: a needs assessment.

Guzman-Cottrill, Judith A / Bryant, Kristina A / Zerr, Danielle M / Harris, Alan A / Alexander, Erin Rose / Boone, Zak / Siegel, Jane D

Infection control and hospital epidemiology

2012 Volume 33, Issue 3, Page(s) 299–301

Abstract: We surveyed Ronald McDonald Houses (RMHs) to assess infection prevention and control (IPC ...

Abstract	We surveyed Ronald McDonald Houses (RMHs) to assess infection prevention and control (IPC) practices. A diverse patient population is served by RMH. Most sites have locally written IPC guidelines, and consultation resources vary, increasing the potential for inconsistent IPC practices. RMH would benefit from a standardized IPC guideline.
MeSH term(s)	Cross Infection/prevention & control ; Health Surveys ; Housing/standards ; Humans ; Infection Control/methods ; Infection Control/standards ; Needs Assessment ; Practice Guidelines as Topic
Language	English
Publishing date	2012-03
Publishing country	United States
Document type	Journal Article
ZDB-ID	639378-0
ISSN	1559-6834 ; 0195-9417 ; 0899-823X
ISSN (online)	1559-6834
ISSN	0195-9417 ; 0899-823X
DOI	10.1086/664054
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Article ; Online: Notes on the Use of Kirchhoff's Laws in Pharmacokinetics.

Siegel, Ronald A

The AAPS journal

2023 Volume 26, Issue 1, Page(s) 8

Abstract: Recent publications by Benet and coworkers, Korzekwa and Nagar, and Rowland et al. signal disagreement regarding the use of Kirchhoff's laws in combining pharmacokinetic parameters, especially clearances and rate constants. Here, it is pointed out that ... ...

Abstract	Recent publications by Benet and coworkers, Korzekwa and Nagar, and Rowland et al. signal disagreement regarding the use of Kirchhoff's laws in combining pharmacokinetic parameters, especially clearances and rate constants. Here, it is pointed out that Kirchhoff's laws as applied to pharmacokinetics simply assert that concentrations are well defined and that molar or mass balances hold. The real issue is how to combine parameters for clearance processes in sequence, which may be reversible, irreversible, or even active in either or both directions. It is also demonstrated that Kirchhoff's laws cannot be used to resolve contradictory results observed in liver transport and clearance. Finally, a simple argument is provided relating nonlinear clearance to apparently anomalous bioavailability observations.
MeSH term(s)	Biological Availability ; Kinetics
Language	English
Publishing date	2023-12-19
Publishing country	United States
Document type	Journal Article
ISSN	1550-7416
ISSN (online)	1550-7416
DOI	10.1208/s12248-023-00875-6
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Article ; Online: Drug-Polymer Miscibility and the Overlap Concentration (C*) as Measured by Rheology: Variation of Polymer Structure.

Sahoo, Anasuya / Siegel, Ronald A

Pharmaceutical research

2023 Volume 40, Issue 9, Page(s) 2229–2237

Abstract: Objectives: Amorphous solid dispersions (ASDs), wherein a drug is molecularly dispersed in a polymer, can improve physical stability and oral bioavailability of poorly soluble drugs. Risk of drug crystallization is usually averted using high polymer ... ...

Abstract	Objectives: Amorphous solid dispersions (ASDs), wherein a drug is molecularly dispersed in a polymer, can improve physical stability and oral bioavailability of poorly soluble drugs. Risk of drug crystallization is usually averted using high polymer concentrations. However, we demonstrated recently that the overlap concentration, C, of polymer in drug melt is the minimum polymer concentration required to maintain drug in the amorphous state following rapid quench. This conclusion was confirmed for several drugs mixed with poly(vinylpyrrolidone) (PVP). Here we assess the solid-state stability of ASDs formulated with a variety of polymers and drugs and at various polymer concentrations (C) and molecular weights (MWs). We further test the hypothesis that degree of drug crystallization decreases with increasing C/C and vanishes when C>C, where C depends on polymer MW and strength of drug-polymer interaction. Methods: We test our hypothesis with ASDs consisting of ketoconazole admixed with polyacrylic acid, polymethacrylic acid and poly (methacrylic acid-co-ethyl acrylate); and felodipine admixed with PVP and poly (vinylpyrrolidone-co-vinyl acetate). Values of C* for polymers in molten drug are rheologically determined. Crystallization behavior is assessed by measuring enthalpy of fusion, ΔH Results: We confirm that ΔH Conclusions: Our findings will aid researchers in designing or selecting appropriate polymers to inhibit crystallization of poorly soluble drugs. This research also suggests that C* as determined by rheology can be used to compare drug-polymer interactions for similar molecular weight polymers.
MeSH term(s)	Polymers/chemistry ; Crystallization ; Felodipine ; Ketoconazole/chemistry ; Rheology ; Solubility ; Povidone/chemistry
Chemical Substances	Polymers ; Felodipine (OL961R6O2C) ; Ketoconazole (R9400W927I) ; poly(vinylpyrrolidone-co-vinyl-acetate) ; Povidone (FZ989GH94E)
Language	English
Publishing date	2023-08-08
Publishing country	United States
Document type	Journal Article
ZDB-ID	843063-9
ISSN	1573-904X ; 0724-8741 ; 0739-0742
ISSN (online)	1573-904X
ISSN	0724-8741 ; 0739-0742
DOI	10.1007/s11095-023-03570-5
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Article ; Online: An Artificial Gut/Absorption Simulator: Understanding the Impact of Absorption on In Vitro Dissolution, Speciation, and Precipitation of Amorphous Solid Dispersions.

Jain, Krutika Meena Harish / Hou, Hao Helen / Siegel, Ronald A

Molecular pharmaceutics

2024 Volume 21, Issue 4, Page(s) 1884–1899

Abstract: Upon dissolution, amorphous solid dispersions (ASDs) of poorly water-soluble compounds can generate supersaturated solutions consisting of bound and free drug species that are in dynamic equilibrium with each other. Only free drug is available for ... ...

Abstract	Upon dissolution, amorphous solid dispersions (ASDs) of poorly water-soluble compounds can generate supersaturated solutions consisting of bound and free drug species that are in dynamic equilibrium with each other. Only free drug is available for absorption. Drug species bound to bile micelles, polymer excipients, and amorphous and crystalline precipitate can reduce the drug solute's activity to permeate, but they can also serve as reservoirs to replenish free drug in solution lost to absorption. However, with multiple processes of dissolution, absorption, and speciation occurring simultaneously, it may become challenging to understand which processes lead to an increase or decrease in drug solution concentration. Closed, nonsink dissolution testing methods used routinely, in the absence of drug removal, allow only for static equilibrium to exist and obscure the impact of each drug species on absorption. An artificial gut simulator (AGS) introduced recently consists of a hollow fiber-based absorption module and allows mass transfer of the drug from the dissolution media at a physiological rate after tuning the operating parameters. In the present work, ASDs of varying drug loadings were prepared with a BCS-II model compound, ketoconazole (KTZ), and hypromellose acetate succinate (HPMCAS) polymer. Simultaneous dissolution and absorption testing of the ASDs was conducted with the AGS, and simple analytical techniques were utilized to elucidate the impact of bound drug species on absorption. In all cases, a lower amount of crystalline precipitate was formed in the presence of absorption relative to the nonsink dissolution "control". However, formation of HPMCAS-bound drug species and crystalline precipitate significantly reduced KTZ absorption. Moreover, at high drug loading, inclusion of an absorption module was shown to enhance ASD dissolution. The rank ordering of the ASDs with respect to dissolution was significantly different when nonsink dissolution versus AGS was used, and this discrepancy could be mechanistically elucidated by understanding drug dissolution and speciation in the presence of absorption.
MeSH term(s)	Solubility ; Crystallization ; Drug Liberation ; Polymers/chemistry ; Gastrointestinal Absorption
Chemical Substances	Polymers
Language	English
Publishing date	2024-03-21
Publishing country	United States
Document type	Journal Article
ZDB-ID	2138405-8
ISSN	1543-8392 ; 1543-8384
ISSN (online)	1543-8392
ISSN	1543-8384
DOI	10.1021/acs.molpharmaceut.3c01180
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Zs.A 6250: Show issues

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Book: Fundamentals and applications of controlled release drug delivery

Siepmann, Jürgen / Siegel, Ronald A. / Rathbone, Michael J.

(Advances in delivery science and technology)

2012

Author's details	Juergen Siepmann ; Ronald A. Siegel ; Michael J. Rathbone
Series title	Advances in delivery science and technology
Language	English
Size	XIII, 592 S. : Ill., graph. Darst., 24 cm
Publisher	Springer
Publishing place	New York u.a.
Publishing country	United States
Document type	Book
HBZ-ID	HT017102065
ISBN	978-1-4614-0880-2 ; 1-4614-0880-6 ; 9781461408819 ; 1461408814
Database	Catalogue ZB MED Medicine, Health

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2012 A 404	order for loan	Magazin

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Article ; Online: Crystallization Inhibition in Molecular Liquids by Polymers above the Overlap Concentration (c*): Delay of the First Nucleation Event.

Song, Sichen / Cui, Shuquan / Sun, Changquan Calvin / Lodge, Timothy P / Siegel, Ronald A

Journal of pharmaceutical sciences

2024

Abstract: Low concentration polymer additives can significantly alter crystal growth kinetics of molecular liquids and glasses. However, the effect of polymer concentration on nucleation kinetics remains poorly understood. Based on an experimentally determined ... ...

Abstract	Low concentration polymer additives can significantly alter crystal growth kinetics of molecular liquids and glasses. However, the effect of polymer concentration on nucleation kinetics remains poorly understood. Based on an experimentally determined first nucleation time (time to form the first critical nucleus, t
Language	English
Publishing date	2024-02-17
Publishing country	United States
Document type	Journal Article
ZDB-ID	3151-3
ISSN	1520-6017 ; 0022-3549
ISSN (online)	1520-6017
ISSN	0022-3549
DOI	10.1016/j.xphs.2024.02.011
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Article ; Online: Delaying the First Nucleation Event of Amorphous Solid Dispersions above the Polymer Overlap Concentration (c*): PVP and PVPVA in Posaconazole.

Song, Sichen / Yao, Xin / Wang, Chenguang / Sun, Changquan Calvin / Siegel, Ronald A

Journal of pharmaceutical sciences

2024

Abstract: A thorough understanding of effects of polymers on crystallization of amorphous drugs is essential for rational design of robust amorphous solid dispersion (ASD), since crystallization of the amorphous drug negates their solubility advantage. In this ... ...

Abstract	A thorough understanding of effects of polymers on crystallization of amorphous drugs is essential for rational design of robust amorphous solid dispersion (ASD), since crystallization of the amorphous drug negates their solubility advantage. In this work, we measured the first nucleation time (t
Language	English
Publishing date	2024-04-27
Publishing country	United States
Document type	Journal Article
ZDB-ID	3151-3
ISSN	1520-6017 ; 0022-3549
ISSN (online)	1520-6017
ISSN	0022-3549
DOI	10.1016/j.xphs.2024.04.026
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Article ; Online: Predetermination of burst times of elastoplastic osmotic capsules.

Jain, Krutika Meena Harish / Siegel, Ronald A

Journal of controlled release : official journal of the Controlled Release Society

2023 Volume 357, Page(s) 422–431

Abstract: Pulsed drug release" for dosing drugs such as vaccines, hormones etc. that require multiple, predetermined release events can be obtained by using capsules that exploit the principle of osmosis to achieve a delayed burst release of their payload. An ... ...

Abstract	"Pulsed drug release" for dosing drugs such as vaccines, hormones etc. that require multiple, predetermined release events can be obtained by using capsules that exploit the principle of osmosis to achieve a delayed burst release of their payload. An objective of this study was to precisely determine the lag time before burst which occurs when the hydrostatic pressure developed due to water influx expands the capsule shell to rupture. A novel 'dip coating' technique was used to encapsulate osmotic agent solution or solid within biodegradable poly(lactic acid-co-glycolic) (PLGA) spherical capsule shells. As a prelude to determine the hydrostatic pressure to burst, first, elastoplastic and failure characterization of PLGA was conducted by a novel "beach ball inflation" technique. The lag time before burst of various capsule configurations was predetermined by modeling the rate of water uptake by the capsule core as a function of capsule shell thickness, radius of the sphere, core osmotic pressure, and the membrane's hydraulic permeability and tensile properties. In vitro release was studied with capsules of different configurations to determine their actual time to burst. The time to rupture predetermined from the mathematical model corroborated with the in vitro results and was found to increase with increases in capsule radius and shell thickness and decrease in osmotic pressure. Pulsatile drug delivery can be achieved by using a multitude of these osmotic capsules consolidated in a single system, each programmed to release the drug payload after a pre-determined time lag.
MeSH term(s)	Capsules ; Drug Delivery Systems/methods ; Osmosis ; Drug Liberation ; Water ; Delayed-Action Preparations
Chemical Substances	Capsules ; Water (059QF0KO0R) ; Delayed-Action Preparations
Language	English
Publishing date	2023-04-18
Publishing country	Netherlands
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	632533-6
ISSN	1873-4995 ; 0168-3659
ISSN (online)	1873-4995
ISSN	0168-3659
DOI	10.1016/j.jconrel.2023.03.029
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Article ; Online: Correction: An Artificial Gut/Absorption Simulator: Description, Modeling, and Validation Using Caffeine.

Jain, Krutika Meena Harish / Hou, Hao Helen / Siegel, Ronald A

The AAPS journal

2022 Volume 24, Issue 5, Page(s) 88

Language	English
Publishing date	2022-08-16
Publishing country	United States
Document type	Published Erratum
ISSN	1550-7416
ISSN (online)	1550-7416
DOI	10.1208/s12248-022-00740-y
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Article ; Online: An Artificial Gut/Absorption Simulator: Simultaneous Evaluation of Desupersaturation and Absorption from Ketoconazole Supersaturated Solutions.

Jain, Krutika Meena Harish / Hou, Hao Helen / Siegel, Ronald A

Journal of pharmaceutical sciences

2022 Volume 112, Issue 8, Page(s) 2212–2222

Abstract: For supersaturating formulations of BCS-II compounds, which by definition have high intestinal permeability, a closed USP apparatus does not provide the necessary absorptive conditions during dissolution. To address this, an artificial gut simulator (AGS) ...

Abstract	For supersaturating formulations of BCS-II compounds, which by definition have high intestinal permeability, a closed USP apparatus does not provide the necessary absorptive conditions during dissolution. To address this, an artificial gut simulator (AGS) has been constructed consisting of a 2.5 mL donor compartment in which a hollow fiber-based absorption module is suspended. Drug from donor diffuses across the hollow fiber membrane to be absorbed by the continuously flowing intraluminal receiver fluid. The membrane surface area and intraluminal fluid flow rate are tuned to obtain the physiologically observed absorption rate constant for a weakly basic, poorly water-soluble model compound, ketoconazole (KTZ). Supersaturated solutions of KTZ were generated in the donor in pH 6.5 phosphate buffer by the pH-shift method in the absence (closed system, control) and presence (open system, biorelevant) of an optimally or suboptimally tuned absorption module. Drug concentrations in the donor and intraluminal fluids were determined by in-line UV spectroscopy. The presence of an absorptive sink reduced the supersaturated solution's crystallization propensity, more so in the case of the optimally tuned AGS. This study demonstrates the significance of simulating absorption of drug at a physiological rate during dissolution studies, especially to predict the performance of formulations of BCS-II drugs.
MeSH term(s)	Ketoconazole/chemistry ; Solubility ; Gastrointestinal Absorption ; Drug Compounding ; Intestinal Absorption/physiology ; Administration, Oral
Chemical Substances	Ketoconazole (R9400W927I)
Language	English
Publishing date	2022-09-24
Publishing country	United States
Document type	Journal Article
ZDB-ID	3151-3
ISSN	1520-6017 ; 0022-3549
ISSN (online)	1520-6017
ISSN	0022-3549
DOI	10.1016/j.xphs.2022.09.017
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