PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-5 (5)
 

Clipboard (0)
None

Select a Filter Below

Journals
Authors
Year of Publication
Document Types
1.  On the Drug-Loading Capacity of Pectin Powder for Direct Compression 
AAPS PharmSciTech  2012;13(2):601-604.
doi:10.1208/s12249-012-9785-4
PMCID: PMC3364367  PMID: 22528548
3-D modelling; colon cancer treatment; colon targeting; compaction behavior; Heckel equation; matrix tablets; mechanical properties
2.  Direct Compression Behavior of Low- and High-Methoxylated Pectins 
AAPS PharmSciTech  2009;11(1):18-26.
The objective of this study was to evaluate possible usefulness of pectins for direct compression of tablets. The deformation behavior of pectin grades of different degree of methoxylation (DM), namely, 5%, 10%, 25%, 35%, 40%, 50%, and 60% were, examined in terms of yield pressures (YP) derived from Heckel profiles for both compression and decompression and measurements of elastic recovery after ejection. All pectin grades showed a high degree of elastic recovery. DM 60% exhibited most plastic deformation (YP 70.4 MPa) whereas DM 5% (104.6 MPa) and DM 10% (114.7 MPa) least. However, DM 60% gave no coherent tablets, whereas tablet tensile strengths for DM 5% and DM 10% were comparable to Starch 1500®. Also, Heckel profiles were similar to Starch 1500®. For sieved fractions (180–250 and 90–125 μm) of DM 25% and DM 40% originating from the very same batch, YPs were alike, indicating minor effects of particle size. These facts indicate that DM is important for the compaction behavior, and batch-to-batch variability should also be considered. Therefore, pectins of low degree of methoxylation may have a potential as direct compression excipients.
doi:10.1208/s12249-009-9349-4
PMCID: PMC2850496  PMID: 20013080
deformation behavior; degree of methoxylation; direct compression; pectin; tensile strength
3.  Direct Compression Behavior of Low- and High-Methoxylated Pectins 
AAPS PharmSciTech  2009;11(1):18-26.
The objective of this study was to evaluate possible usefulness of pectins for direct compression of tablets. The deformation behavior of pectin grades of different degree of methoxylation (DM), namely, 5%, 10%, 25%, 35%, 40%, 50%, and 60% were, examined in terms of yield pressures (YP) derived from Heckel profiles for both compression and decompression and measurements of elastic recovery after ejection. All pectin grades showed a high degree of elastic recovery. DM 60% exhibited most plastic deformation (YP 70.4 MPa) whereas DM 5% (104.6 MPa) and DM 10% (114.7 MPa) least. However, DM 60% gave no coherent tablets, whereas tablet tensile strengths for DM 5% and DM 10% were comparable to Starch 1500®. Also, Heckel profiles were similar to Starch 1500®. For sieved fractions (180–250 and 90–125 μm) of DM 25% and DM 40% originating from the very same batch, YPs were alike, indicating minor effects of particle size. These facts indicate that DM is important for the compaction behavior, and batch-to-batch variability should also be considered. Therefore, pectins of low degree of methoxylation may have a potential as direct compression excipients.
doi:10.1208/s12249-009-9349-4
PMCID: PMC2850496  PMID: 20013080
deformation behavior; degree of methoxylation; direct compression; pectin; tensile strength
4.  Influence of Position and Size of Substituents on the Mechanism of Partitioning: A Thermodynamic Study on Acetaminophens, Hydroxybenzoic Acids, and Parabens 
AAPS PharmSciTech  2008;9(1):205-216.
The objective of the present investigation was to study the influence of size, nature, and topology of substituents on the thermodynamic characteristics of sublimation, fusion, solubility, solvation, and partitioning processes of some drug and druglike molecules. Thermodynamic functions of sublimation process 2-acetaminophen and 3-acetaminophen were obtained on the basis of temperature dependencies of vapor pressure by the transpiration method. Thermodynamic characteristics of solubility processes in water, n-octanol, and n-hexane were calculated from the temperature dependencies of solubility using the solubility saturation method. For evaluation of fusion parameters, differential scanning calorimetry was used. A new approach to distinguishing specific and nonspecific energetic terms in the crystal lattice was developed. Specific and nonspecific solvation terms were distinguished using the transfer from the “inert” n-hexane to the other solvents. For the acetaminophen compounds and for some related drug molecules, the correlation between melting points and a parameter describing the ratio between specific and nonspecific interaction in the crystal lattices was obtained. A diagram enabling analysis of the mechanism of the partitioning process was applied. It was found that for isomers of benzoic acids and for acetaminophens, the position of substituents affects the mechanism of the partitioning process but not the extent of partitioning (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta G_{{\text{tr}}}^{\text{0}}$$\end{document} values). In contrast to this, an increased size of substituents (parabens) leads to essential changes in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta G_{{\text{tr}}}^{\text{0}}$$\end{document} values, but the mechanism of the partitioning process stays the same.
doi:10.1208/s12249-008-9033-0
PMCID: PMC2976908  PMID: 18446483
partitioning; solubility; solvation; sublimation; thermodynamics; transfer
5.  Solvation and hydration characteristics of ibuprofen and acetylsalicylic acid 
AAPS PharmSci  2004;6(1):22-30.
Ibuprofen and acetylsalicylic acid were studied by thermoanalytical methods: sublimation calorimetry, solution calorimetry, and with respect to solubility. Upon measuring the temperature dependences of the saturated vapor pressure, enthalpies of sublimation, ΔHsub0, as well as the entropies of sublimation, ΔHsub0, and their respective relative fractions in the total process were calculated. The Gibbs energy of solvation in aliphatic alcohols as well as the enthalpic and entropic fractions thereof were also studied and compared with the respective properties of model substances and other nonsteroidal antiinflammatory drugs (benzoic acid, diflunisal, flurbiprofen, ketoprofen, and naproxen). In all cases, enthalpy was found to be the driving force of the solvation process. Correlations were derived between Gibbs energy of solvation in octanol, ΔGsolvOct, and the transfer Gibbs energy from water to octanol, ΔGtr0. Influence of mutual octanol and water solubilities on the driving force of partitioning is discussed. An enthalpy-entropy-compensation effect in octanol was observed, and consequences of deviation from the general trend are also discussed.
doi:10.1208/ps060103
PMCID: PMC2750938  PMID: 18465255
ibuprofen; acetylsalicylic acid; NSAID; sublimation; solvation; hydration; plasma half-life

Results 1-5 (5)