The interaction of polyvinylpyrrolidone with aromatic compounds in aqueous solution Part IV. Evaluation of the co-operativity parameter, and the methylene-group contribution to the binding strength, for the alkyl parahydroxybenzoates

Molyneux, Philip; Cornarakis-Lentzos, M.

doi:10.1007/bf01383355

Cited by 21 publications

(7 citation statements)

References 29 publications

(45 reference statements)

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“…PVP interactions with the propylparaben crystal are seemingly hydrophobic in nature and the pyrrolidone ring is involved in hydrophobic interactions with both the propylparaben propyl tail and the aromatic ring. These findings are in agreement with the results obtained by Molyneux and Cornarakis-Lentzos, who studied binding interactions between paraben esters and PVP and evaluated the contribution of hydrophobic interactions between methylene groups in the paraben alkyl tail and PVP to the binding strength [49]. In some cases, the PVP monomeric unit exchanged with propylparaben molecules, intercalating between propylparaben layers (between the p-stacked propylparaben aromatic rings).…”

Section: Simulations Of Crystal Growth Inhibitionsupporting

confidence: 89%

Formation of organic nanoparticles from volatile microemulsions

Margulis‐Goshen

Netivi

Major

et al. 2010

Journal of Colloid and Interface Science

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Section: Simulations Of Crystal Growth Inhibitionsupporting

confidence: 89%

Formation of organic nanoparticles from volatile microemulsions

Margulis‐Goshen

Netivi

Major

et al. 2010

Journal of Colloid and Interface Science

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“…This seems to be the first estimate of this methylene-group contribution to true hydrophobic bonding for such a wide range of alkyl chain lengths, and indeed it seems to be the first indication that it is constant over such a range. That this is a reasonable va lue is supported by the fact that it is comparable to the value of -1.0 kJ mol" 1 we obtained for the equivalent contribution to the free energy of the binding of alkyl 4-hydroxybenzoates by PVP in aqueous solution (29), where each additional methylene chain in the cosolute ester group is taken to interact with a methylene group on the PVP chain. Furthermore, viewing this hydrophobic association as the transfer of each methylene group from a wholly aqueous environment to the hydrophobic-association environment (i.e., adjacent to the methylene group on the other alkyl chain), this gives the free ener gy of transfer for a single methylene group as -0.7 kJ mol" 1 .…”

Section: Free Energies Of Hydrophobic Bonding Between Alkylmentioning

confidence: 63%

“…solvent is water-saturated that in the case of PVA, it may be questionable to take the methyl group of the acetate as corresponding to alkyl chain length always follow the behavior expected for it as the first member of the alkyl series, it is significant that we ourselves found, in our studies on the binding of alkyl (i.e., methyl to butyl) 4-hydroxybenzoates to PVP(29), that the free energy of binding (represented by the logarithm of the binding constant) was a linear function…”

mentioning

confidence: 96%

Role of Labile Cross-Links in the Behavior of Water-Soluble Polymers

Molyneux¹

1991

ACS Symposium Series

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The labile crosslinks (herein called "liaisons"), involving noncovalent and/or reversible covalent interactions, that arise between polymer chains when they come into contact, play an important part in the solution behavior of water-soluble polymers. Three cases are discussed in this paper: (1) a simple homopolymer alone in solution, where intrachain liaisons are the so-called "long-range interactions" which influence the conformational size of the molecule; (2) copolymers with a minor content of a comonomer unit which associates by hydrophobic or other interactions, where the application of liaison theory to two types of hydrophobically-associating copolymers -poly(vinyl acetate-co-vinyl alcohol), and alkyl-substituted hydroxyethylcellulose -leads to the establishment of a scale of free energies of hydrophobic-bonding between alkyl chains which is linear with chain length for the range n = 1 to 16; (3) cosolute-binding systems, where extra liaisons may arise from associations between the bound cosolute molecules.The aim of this paper is to show how the behavior of water-soluble polymers -especially their conformational size, their precipitability and phase-separation behavior, and their rheology -is affected by the labile crosslinks that arise between their chains when they come into contact. For convenience and brevity, these labile crosslinks will be called liaisons throughout the rest of the paper. Characteristics of LiaisonsA liaison is taken to be formed wherever there is a contact either between two distantly-connected parts of the same polymer chain ("intrachain") or between parts of two different polymer chains

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“…This happens when strong interactions between two solutes impede interaction with water. Well-known examples include: hydrophobic ion pairing where an ion of a water-soluble molecule is electrostatically coupled to a hydrophobic counterion, , insoluble complex formation between two highly water-soluble polymers such as polyacrylic acid and polyvinyl pyrrolidone, and insoluble complex formation between a small molecule and a polymer. , With regard to the latter example, several studies document the formation of insoluble complexes of polyvinylpyrrolidone with phenolic compounds. − …”

Section: Discussionmentioning

confidence: 99%

Dissolution Mechanisms of Amorphous Solid Dispersions: Role of Drug Load and Molecular Interactions

Deac

Indulkar

et al. 2022

Mol. Pharmaceutics

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High drug load amorphous solid dispersions (ASDs) have been a challenge to formulate partially because drug release is inhibited at high drug loads. The maximum drug load prior to inhibition of release has been termed the limit of congruency (LoC) and has been most widely studied for copovidone (PVPVA)-based ASDs. The terminology was derived from the observation that below LoC, the polymer controlled the kinetics and the drug and the polymer released congruently, while above LoC, the release rates diverged and were impaired. Recent studies show a correlation between the LoC value and drug−polymer interaction strength, where a lower LoC was observed for systems with stronger interactions. The aim of this study was to investigate the causality between drug−PVPVA interaction strength and LoC. Four chemical analogues with diverse abilities to interact with PVPVA were used as model drugs. The distribution of the polymer between the dilute aqueous phase and the insoluble nanoparticles containing drug was studied with solution nuclear magnetic resonance spectroscopy and traditional separation techniques to understand the thermodynamics of the systems in a dilute environment. Polymer diffusion to and from ASD particles suspended in aqueous solution was monitored for drug loads above the LoC to investigate the thermodynamic driving force for polymer release. The surface composition of ASD compacts before and after exposure to buffer was studied with Fourier transform infrared spectroscopy to capture potential kinetic barriers to release. It was found that ASD compacts with drug loads above the LoC formed an insoluble barrier on the surface that was in pseudo-equilibrium with the aqueous phase and prevented further release of drugs and polymers during dissolution. The insoluble barrier contained a substantial amount of the polymer for the strongly interacting drug−polymer systems. In contrast, a negligible amount was found for the weakly interacting systems. This observation provides an explanation for the ability of strongly interacting systems to form an insoluble barrier at lower drug loads. The study highlights the importance of thermodynamic and kinetic factors on the dissolution behavior of ASDs and provides a potential framework for maximizing the drug load in ASDs.

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The interaction of polyvinylpyrrolidone with aromatic compounds in aqueous solution Part IV. Evaluation of the co-operativity parameter, and the methylene-group contribution to the binding strength, for the alkyl parahydroxybenzoates

Abstract: The interaction of polyvinylpyrrolidone with aromatic compounds in aqueous solution.Part IV. Evaluation of the co-operativity parameter, and the methylene-group contribution to the binding strength, for the alkyl parahydroxybenzoates. *) P. Molyneux and M. Cornarakis-Lentzos

Cited by 21 publications

References 29 publications

Formation of organic nanoparticles from volatile microemulsions

Formation of organic nanoparticles from volatile microemulsions

Role of Labile Cross-Links in the Behavior of Water-Soluble Polymers

Dissolution Mechanisms of Amorphous Solid Dispersions: Role of Drug Load and Molecular Interactions

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