| 1. |
- Avdeef, Alex, et al.
(författare)
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Caco-2 permeability of weakly basic drugs predicted with the Double-Sink PAMPA method :
- 2005
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987. ; 24:4, s. 333-49
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to analyze pH-dependent permeability of cationic drugs in Caco-2 cell monolayers using the method and to correlate the results with those obtained in PAMPA (parallel artificial membrane permeability assay). The pH-dependent permeability of verapamil and propranolol was studied in Caco-2 cell monolayers. The data were subsequently processed using software developed for the PAMPA method. Literature values for an additional nine cationic drugs were also analyzed. Double-Sink PAMPA data were also obtained for the same cationic drugs, to compare with the Caco-2 data. The Algorithm Builder program was then used to develop a predictive model of Caco-2 permeability based on PAMPA permeability and calculated Abraham molecular descriptors. From the relationship between permeability and pH it was shown that in PAMPA only the uncharged form of the drugs permeated across the membrane barrier, while charged and ionized forms of the drugs were significantly permeable in Caco-2. The charged-form permeability, Pi, was therefore determined and subsequently subtracted from all permeability coefficients in Caco-2 prior to the comparison with PAMPA. The resulting intrinsic permeability coefficients (Po) obtained in Caco-2 were successfully related to those derived from the PAMPA model. In this study we have shown that permeability coefficients obtained in PAMPA can predict the passive transcellular permeability in Caco-2.
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| 2. |
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| 3. |
- Bergström, Christel A.S. 1973-, et al.
(författare)
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Perspectives in solubility measurement and interpretation
- 2019
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Ingår i: ADMET AND DMPK. - : IAPC PUBLISHING. - 1848-7718. ; 7:2, s. 88-105
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Forskningsöversikt (refereegranskat)abstract
- Several key topics in solubility measurement and interpretation are briefly summarized and illustrated with case studies drawing on published solubility determinations as a function of pH. Featured are examples of ionizable molecules that exhibit solubility-pH curve distortion from that predicted by the traditionally used Henderson-Hasselbalch equation and possible interpretations for these distortions are provided. The scope is not exhaustive; rather it is focused on detailed descriptions of a few cases. Topics discussed are limitations of kinetic solubility, 'brick-dust and grease-balls,' applications of simulated and human intestinal fluids, supersaturation and the relevance of pre-nucleation clusters and sub-micellar aggregates in the formation of solids, drug-buffer/excipient complexation, hydrotropic solubilization, acid-base 'supersolubilization,' cocrystal route to supersaturation, as well as data quality assessment and solubility prediction. The goal is to highlight principles of solution equilibria - graphically more than mathematically - that could invite better assay design, to result in improved quality of measurements, and to impart a deeper understanding of the underlying solution chemistry in suspensions of drug solids. The value of solid state characterizations is stressed but not covered explicitly in this mini-review.
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| 4. |
- Di, Li, et al.
(författare)
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Evidence-based approach to assess passive diffusion and carrier-mediated drug transport
- 2012
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Ingår i: Drug Discovery Today. - : Elsevier BV. - 1359-6446 .- 1878-5832. ; 17:15-16, s. 905-912
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Forskningsöversikt (refereegranskat)abstract
- Evidence supporting the action of passive diffusion and carrier-mediated (CM) transport in drug bioavailability and disposition is discussed to refute the recently proposed theory that drug transport is CM-only and that new transporters will be discovered that possess transport characteristics ascribed to passive diffusion. Misconceptions and faulty speculations are addressed to provide reliable guidance on choosing appropriate tools for drug design and optimization.
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| 5. |
- Di, Li, et al.
(författare)
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The Critical Role of Passive Permeability in Designing Successful Drugs
- 2020
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Ingår i: ChemMedChem. - : Wiley. - 1860-7179 .- 1860-7187. ; 15:20, s. 1862-1874
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Forskningsöversikt (refereegranskat)abstract
- Passive permeability is a key property in drug disposition and delivery. It is critical for gastrointestinal absorption, brain penetration, renal reabsorption, defining clearance mechanisms and drug-drug interactions. Passive diffusion rate is translatable across tissues and animal species, while the extent of absorption is dependent on drug properties, as well as in vivo physiology/pathophysiology. Design principles have been developed to guide medicinal chemistry to enhance absorption, which combine the balance of aqueous solubility, permeability and the sometimes unfavorable compound characteristic demanded by the target. Permeability assays have been implemented that enable rapid development of structure-permeability relationships for absorption improvement. Future advances in assay development to reduce nonspecific binding and improve mass balance will enable more accurately measurement of passive permeability. Design principles that integrate potency, selectivity, passive permeability and other ADMET properties facilitate rapid advancement of successful drug candidates to patients.
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| 6. |
- Fagerberg, Jonas H., et al.
(författare)
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Dissolution Rate and Apparent Solubility of Poorly Soluble Drugs in Biorelevant Dissolution Media
- 2010
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Ingår i: Molecular pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 7:5, s. 1419-1430
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Tidskriftsartikel (refereegranskat)abstract
- A series of poorly soluble BCS class II compounds with "grease ball" characteristics were assessed for solubility and dissolution rate in biorelevant dissolution media (BDM) with the purpose of investigating which molecular structures gain most in solubility when dissolved under physiologically relevant conditions. The compounds were studied in four media (simulated intestinal fluid in fasted (FaSSIF pH 6.5) and fed state (FeSSIF pH 5.0), and their corresponding blank buffers (FaSSIF(blk) and FeSSIFblk)) at a temperature of 37 degrees C. The experimental results were used to analyze which molecular characteristics are of importance for the solubility in BDM and for in silico modeling using multivariate data analysis. It was revealed that a majority of the compounds exhibited a higher dissolution rate and higher solubility in the FaSSIF and FeSSIF than in their corresponding blank buffers. Compounds which were neutral or carried a positive charge were more soluble in FeSSIF than FaSSIF. The acidic compounds displayed clear pH dependency, although the higher concentration of solubilizing agents in FeSSIF than FaSSIF also improved the solubility. Five of the ten compounds were upgraded to BCS class I when dissolved in FaSSIF or FeSSIF, i.e., the maximum dose of these compounds given orally was soluble in 250 mL of these BDMs. Lipophilicity as described by the log D-oct value was identified as a good predictor of the solubilization ratio (R-2 = 0.74), and computed molecular descriptors were also shown to successfully predict the solubilities in BDM for this data set. To conclude, the physiological solubility of "grease ball" molecules may be largely underestimated in in vitro solubility assays unless BDM is used. Moreover, the results herein indicate that the improvement obtained in BDM may be possible to predict from chemical features alone.
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| 7. |
- Persson, Anita M., 1975-
(författare)
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Evaluation of a Miniaturized Rotating Disk Apparatus for In Vitro Dissolution Rate Measurements in Aqueous Media : Correlation of In Vitro Dissolution Rate with Apparent Solubility
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The general aim of this thesis was to evaluate a newly designed and constructed miniaturized rotating disk apparatus for in vitro dissolution rate measurements of different drug substances from all of the classes in the Biopharmaceutical Classification System (BCS). The new equipment is based on a low volume flow-through cell of Plexiglas, a gold plated magnetic bar and a special designed press. The disk of drug substance (approx. 5 mg) is placed eccentrically in the bar. Rotation speeds were set with a graded magnetic stirrer. An external HPLC pump delivered a continuous flow of aqueous medium to the flow-through cell during dissolution testing. A reversed phase high-performance liquid chromatography system using diode array detection (RP-HPLC-DAD) was coupled online to the new equipment. The injections from the miniaturized rotating disk outlet into the quantifying HPLC system were controlled by a six-position switching valve. The injection volumes from the valve and the autosampler, used for the external standards, were statistically evaluated to match each other volumetrically. No analyses were longer than three minutes, using isocratic mode. A traditional USP rotating disk apparatus was used as a reference system and the two instruments were shown to be statistically dissimilar in the numerical dissolution rate values probably due to different hydrodynamics, but had approximately the same precision/repeatability. When correlating the logarithmic values of the in vitro dissolution rate (G) with the apparent solubility (S), using shake-flask methodology in the solubility studies, the two apparatuses gave the same correlation patterns. Further correlation studies were done where the media components were altered by the use of different buffer species or additives into the buffers, such as inorganic salts. Chemometric tools, e.g. orthogonal partial least squares (OPLS), were used to better evaluate the most influential factors for G and S in different media. The most significant factor for a model basic drug substance (terfenadine) was pH, followed by the ionic strength (I) and added sodium chloride in one of the media. However, the surfactants in the Fasted State Simulated Intestinal Fluid (FaSSIF-V2) were found to be insignificant for G and S in this study (using a 95% confidence interval). The new miniaturized apparatus is a promising prototype for in vitro dissolution rate measurements both for early screening purposes and in dissolution testing during drug development, but needs further instrumental improvements.
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| 8. |
- Smith, Dennis, et al.
(författare)
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Passive Lipoidal Diffusion and Carrier-Mediated Cell Uptake Are Both Important Mechanisms of Membrane Permeation in Drug Disposition
- 2014
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 11:6, s. 1727-1738
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Forskningsöversikt (refereegranskat)abstract
- Recently, it has been proposed that drug permeation is essentially carrier-mediated only and that passive lipoidal diffusion is negligible. This opposes the prevailing hypothesis of drug permeation through biological membranes, which integrates the contribution of multiple permeation mechanisms, including both carrier-mediated and passive lipoidal diffusion, depending on the compound's properties, membrane properties, and solution properties. The prevailing hypothesis of drug permeation continues to be successful for application and prediction in drug development. Proponents of the carrier-mediated only concept argue against passive lipoidal diffusion. However, the arguments are not supported by broad pharmaceutics literature. The carrier-mediated only concept lacks substantial supporting evidence and successful applications in drug development.
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| 9. |
- Sugano, Kiyohiko, et al.
(författare)
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Coexistence of passive and carrier-mediated processes in drug transport
- 2010
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Ingår i: Nature reviews. Drug discovery. - : Springer Science and Business Media LLC. - 1474-1776 .- 1474-1784. ; 9:8, s. 597-614
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Tidskriftsartikel (refereegranskat)abstract
- The permeability of biological membranes is one of the most important determinants of the pharmacokinetic processes of a drug. Although it is often accepted that many drug substances are transported across biological membranes by passive transcellular diffusion, a recent hypothesis speculated that carrier-mediated mechanisms might account for the majority of membrane drug transport processes in biological systems. Based on evidence of the physicochemical characteristics and of in vitro and in vivo findings for marketed drugs, as well as results from real-life discovery and development projects, we present the view that both passive transcellular processes and carrier-mediated processes coexist and contribute to drug transport activities across biological membranes.
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