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Roland Bodmeier - One of the best experts on this subject based on the ideXlab platform.
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drug release from and sterilization of in situ cubic phase forming monoglyceride drug delivery systems
European Journal of Pharmaceutics and Biopharmaceutics, 2010Co-Authors: Abid Riaz Ahmed, A Dashevsky, Roland BodmeierAbstract:Since a monoglyceride-based cubic phase is too viscous to be injected parenterally, mixtures of monoglyceride, water and water-miscible cosolvents were investigated as low viscosity injectable in situ cubic phase-forming formulations. Upon contact with the release medium, a highly viscous cubic phase formed rapidly and served as an extended release matrix for the oligonucleotide drug. Extended drug release was obtained with all formulations. The drug release followed the square root of time relationship indicating a diffusion-controlled release mechanism. The release depended on the type of cosolvent and followed the order of ethanol > PEG 300 > 2-pyrrolidone > DMSO. Higher water or Monoglycerides contents decreased the drug release because of an increased viscosity and increased swollen matrix thickness. The bioburden of different commercially available Monoglycerides and of the prepared in situ cubic phase-forming formulations met USP XXIII requirements. Monoglycerides can be successfully sterilized by gamma irradiation or by autoclaving and the in situ cubic phase-forming formulations by autoclaving and aseptic filtration. The Monoglycerides and in situ cubic phase-forming formulations retained their phase behaviour and release properties after sterilization.
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effect of dissolution media and additives on the drug release from cubic phase delivery systems
Journal of Controlled Release, 1997Co-Authors: Chinming Chang, Roland BodmeierAbstract:Abstract Unsaturated Monoglycerides such as monooleate or monolinoleate form a physically stable, highly viscous cubic phase in contact with excess aqueous medium. The swelling and release properties of drug-loaded monoglyceride matrices were evaluated with regard to the development of an oral sustained release delivery system. The swelling capacity of the amphiphilic monoglyceride matrix was higher in 0.1 M pH 7.4 phosphate buffer than in 0.1 N HCl. However, the drug release was opposite in trend, with propranolol HCl being released at a slower rate in pH 7.4 buffer. This was attributed to the presence of free fatty acids in the monoglyceride matrix, which were ionized at pH 7.4, but unionized in 0.1 N HCl. The formation of insoluble complexes with the cationic drug, propranolol HCl, at the higher pH explained the slower release. The incorporation of oleic acid in the monoglyceride matrices further confirmed the influence of fatty acids and was a tool to manipulate the release of cationic drugs. The inclusion of oleic acid and propranolol HCl resulted in the concentration- and pH-dependent formation of other mesophases besides the cubic phase. Varying the ionic strength of the dissolution medium had a minor effect on both swelling and drug release from the nonionic, amphiphilic Monoglycerides. While the cubic phase stayed physically intact in enzyme-free simulated gastrointestinal fluids, the addition of bile salts to the pH 7.4 buffer resulted in the dispersion and disappearance of the swollen monoglyceride phase.
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swelling of and drug release from monoglyceride based drug delivery systems
Journal of Pharmaceutical Sciences, 1997Co-Authors: Chinming Chang, Roland BodmeierAbstract:Depending on the water content, unsaturated Monoglycerides form various liquid crystalline phases, which can be used as sustained-release carriers. The aim of this study was to investigate the water uptake of and drug release from melt-congealed monoglyceride-based drug carriers. The water uptake of the unsaturated Monoglycerides monoolein and monolinolein followed second-order swelling kinetics and levelled off at about 50% water content, at which a highly viscous cubic phase was formed. The rapid formation of the cubic phase suggested that the drug release occurred mainly from this phase. The drug release followed the square-root of time relationship during the initial release phase. Chlor-pheniramine maleate, an amphiphilic drug was not completely released because of binding to the cubic phase. The rate of water uptake increased and the maximum water uptake decreased with increasing temperature. The drug release could be controlled by varying the surface-to-volume ratio, the drug loading, and the water content of the lipid matrix. It was independent of the source of monoolein.
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Binding of drugs to monoglyceride-based drug delivery systems
International Journal of Pharmaceutics, 1997Co-Authors: Chinming Chang, Roland BodmeierAbstract:Abstract Unsaturated Monoglycerides such as glycerol monooleate or monolinoleate form a cubic phase at body temperature and with excess water. This mesophase has been used as sustained release carrier. During dissolution studies, an incomplete release of various highly water-soluble drugs was observed with the cubic phase. Amphiphilic drugs such as chlorpheniramine maleate, diltiazem HC1 or propranolol HC1 were bound to the monoglyceride and incompletely released. The absorption of various drugs to the Monoglycerides was studied. The surface activity of the drugs as measured by the surface tension of drug solutions-correlated well with the drug absorption to the cubic phase and the release profiles. A pH-dependent drug absorption was observed with the cationic drug, propranolol HC1. More drug was absorbed at a higher pH, probably because of the complexation with free fatty acids being present in the monoglyceride. The solubilization of the drug molecules in the different domains of the amphiphilic, hydrated Monoglycerides affected the phase transformation. Above a certain concentration, hydrophilic drugs (e.g. chlorpheniramine maleate, propranolol HCI) transformed the cubic phase into a lamellar phase and lipophilic drugs (ibuprofen, propranolol) into an inverted hexagonal phase.
Chinming Chang - One of the best experts on this subject based on the ideXlab platform.
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effect of dissolution media and additives on the drug release from cubic phase delivery systems
Journal of Controlled Release, 1997Co-Authors: Chinming Chang, Roland BodmeierAbstract:Abstract Unsaturated Monoglycerides such as monooleate or monolinoleate form a physically stable, highly viscous cubic phase in contact with excess aqueous medium. The swelling and release properties of drug-loaded monoglyceride matrices were evaluated with regard to the development of an oral sustained release delivery system. The swelling capacity of the amphiphilic monoglyceride matrix was higher in 0.1 M pH 7.4 phosphate buffer than in 0.1 N HCl. However, the drug release was opposite in trend, with propranolol HCl being released at a slower rate in pH 7.4 buffer. This was attributed to the presence of free fatty acids in the monoglyceride matrix, which were ionized at pH 7.4, but unionized in 0.1 N HCl. The formation of insoluble complexes with the cationic drug, propranolol HCl, at the higher pH explained the slower release. The incorporation of oleic acid in the monoglyceride matrices further confirmed the influence of fatty acids and was a tool to manipulate the release of cationic drugs. The inclusion of oleic acid and propranolol HCl resulted in the concentration- and pH-dependent formation of other mesophases besides the cubic phase. Varying the ionic strength of the dissolution medium had a minor effect on both swelling and drug release from the nonionic, amphiphilic Monoglycerides. While the cubic phase stayed physically intact in enzyme-free simulated gastrointestinal fluids, the addition of bile salts to the pH 7.4 buffer resulted in the dispersion and disappearance of the swollen monoglyceride phase.
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swelling of and drug release from monoglyceride based drug delivery systems
Journal of Pharmaceutical Sciences, 1997Co-Authors: Chinming Chang, Roland BodmeierAbstract:Depending on the water content, unsaturated Monoglycerides form various liquid crystalline phases, which can be used as sustained-release carriers. The aim of this study was to investigate the water uptake of and drug release from melt-congealed monoglyceride-based drug carriers. The water uptake of the unsaturated Monoglycerides monoolein and monolinolein followed second-order swelling kinetics and levelled off at about 50% water content, at which a highly viscous cubic phase was formed. The rapid formation of the cubic phase suggested that the drug release occurred mainly from this phase. The drug release followed the square-root of time relationship during the initial release phase. Chlor-pheniramine maleate, an amphiphilic drug was not completely released because of binding to the cubic phase. The rate of water uptake increased and the maximum water uptake decreased with increasing temperature. The drug release could be controlled by varying the surface-to-volume ratio, the drug loading, and the water content of the lipid matrix. It was independent of the source of monoolein.
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Binding of drugs to monoglyceride-based drug delivery systems
International Journal of Pharmaceutics, 1997Co-Authors: Chinming Chang, Roland BodmeierAbstract:Abstract Unsaturated Monoglycerides such as glycerol monooleate or monolinoleate form a cubic phase at body temperature and with excess water. This mesophase has been used as sustained release carrier. During dissolution studies, an incomplete release of various highly water-soluble drugs was observed with the cubic phase. Amphiphilic drugs such as chlorpheniramine maleate, diltiazem HC1 or propranolol HC1 were bound to the monoglyceride and incompletely released. The absorption of various drugs to the Monoglycerides was studied. The surface activity of the drugs as measured by the surface tension of drug solutions-correlated well with the drug absorption to the cubic phase and the release profiles. A pH-dependent drug absorption was observed with the cationic drug, propranolol HC1. More drug was absorbed at a higher pH, probably because of the complexation with free fatty acids being present in the monoglyceride. The solubilization of the drug molecules in the different domains of the amphiphilic, hydrated Monoglycerides affected the phase transformation. Above a certain concentration, hydrophilic drugs (e.g. chlorpheniramine maleate, propranolol HCI) transformed the cubic phase into a lamellar phase and lipophilic drugs (ibuprofen, propranolol) into an inverted hexagonal phase.
Gordon J T Tiddy - One of the best experts on this subject based on the ideXlab platform.
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the effect of Monoglycerides on the crystallisation of triglyceride
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2016Co-Authors: Abdullatif Alfutimie, Nadeen Aljanabi, Robin Curtis, Gordon J T TiddyAbstract:Abstract There has been increased interest recently in how different lipids interact with each other in solid phases and in the properties and consequences of the inter-lipid associations. The crystallisation behaviour of the triglycerides is noticeably influenced by the presence of Monoglycerides. The main aim of this work was to extend studies of the influences of saturated and unsaturated Monoglycerides on the crystallization of triglycerides. We aim to gain more insight into the effect of Monoglycerides on miglyol oil, palm oil and olive oil crystallization. Optical microscopy, differential scanning calorimetry (DSC), small X-ray scattering (SAXS) and wide X-ray scattering (WAXS) were used in this study. Our results suggest that the presence of saturated monoglyceride affects the oil crystallization behaviour. Conversely, triglycerides with unsaturated fatty acid chains show little impact. The results provide evidence that saturated and unsaturated monglycerides are incorporated into the α- phase of palm oil.
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the phase behaviour of mixed saturated and unsaturated Monoglycerides in hydrophobic system
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015Co-Authors: Abdullatif Alfutimie, Robin Curtis, Gordon J T TiddyAbstract:Lyotropic liquid crystals are formed on the dissolution of most surfactants in water as represented by regions on the phase diagram, and are more common than micellar solutions. Monoglycerides with saturated or unsaturated fatty acids are one of the most commonly used food surfactants. While there is considerable interest in the behaviour of Monoglycerides mixed with oils (particularly triglycerides), limited information is available regarding the phase behaviour of such systems. We have examined the phase behaviour of mixed saturated and unsaturated Monoglycerides1:1 (by weight) together with different oils systems. The main technique employed was X-ray diffraction, supplemented by optical microscopy, proton nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). Our results suggest that six phases (L2, α-gel phase, sub α- phase, β1 and oil crystallisation phase (β` for palm oil or β2 for miglyol oil or olive oil) were observed for G50/oil mixture. Furthermore, this paper proves that miglyol and palm oil incorporate into α-gel phase of G50. In contrast, olive oil dose not incorporate into α-gel phase of G50.
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gel phase lβ formation by mixed saturated and unsaturated Monoglycerides
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014Co-Authors: Abdullatif Alfutimie, Robin Curtis, Gordon J T TiddyAbstract:Abstract It is commonly thought that the α-gel phase (Lβ) consists of surfactant layers where the alkyl chains are mostly in the all-trans conformation and packed in a two dimensional hexagonal lattice with rotational disorder, but no translational mobility. We have examined the phase behaviour of mixed saturated and unsaturated Monoglycerides [glycerol monostearate (GMS) and glycerol monooleate (GMO)] to investigate whether gel phases will be formed from unsaturated Monoglycerides. In addition, this study examined the effect of aging on the phase behaviour of the mixture. An array of techniques was employed to investigate the phase behaviour as function of temperature: optical microscopy to observe optical textures, differential scanning calorimetry (DSC) to determine the transition enthalpies between phases, and nuclear magnetic resonance (NMR) to study surfactant mobility in the various phases. Additionally, we used small angle X-ray scattering (SAXS) to characterise the different mesomorphic phases at different temperatures. Finally, Fourier transform infrared spectroscopy (FTIR) was used to study the states of hydrogen bonding in the systems. Our results suggest that various phases for GMS/GMO mixture were observed α-gel (Lβ) phase, new α-gel (Lβ1) structure, β1 crystal phase, sub-α phase, β2-crystal, as well as an isotropic, L2, phase. Additionally there is some unsaturated monoglyceride incorporated into the α-gel phase of the saturated monoglyceride, which generated the new type of α-gel structure (Lβ1) characterised by a more disordered structural arrangement. GMO cannot pack in the same hexagonal structure as the α-gel phase of saturated lipids (Lβ). During storage, all monoglyceride structures transform to a highly ordered packing β crystal structure.
Abdullatif Alfutimie - One of the best experts on this subject based on the ideXlab platform.
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the effect of Monoglycerides on the crystallisation of triglyceride
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2016Co-Authors: Abdullatif Alfutimie, Nadeen Aljanabi, Robin Curtis, Gordon J T TiddyAbstract:Abstract There has been increased interest recently in how different lipids interact with each other in solid phases and in the properties and consequences of the inter-lipid associations. The crystallisation behaviour of the triglycerides is noticeably influenced by the presence of Monoglycerides. The main aim of this work was to extend studies of the influences of saturated and unsaturated Monoglycerides on the crystallization of triglycerides. We aim to gain more insight into the effect of Monoglycerides on miglyol oil, palm oil and olive oil crystallization. Optical microscopy, differential scanning calorimetry (DSC), small X-ray scattering (SAXS) and wide X-ray scattering (WAXS) were used in this study. Our results suggest that the presence of saturated monoglyceride affects the oil crystallization behaviour. Conversely, triglycerides with unsaturated fatty acid chains show little impact. The results provide evidence that saturated and unsaturated monglycerides are incorporated into the α- phase of palm oil.
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the phase behaviour of mixed saturated and unsaturated Monoglycerides in hydrophobic system
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015Co-Authors: Abdullatif Alfutimie, Robin Curtis, Gordon J T TiddyAbstract:Lyotropic liquid crystals are formed on the dissolution of most surfactants in water as represented by regions on the phase diagram, and are more common than micellar solutions. Monoglycerides with saturated or unsaturated fatty acids are one of the most commonly used food surfactants. While there is considerable interest in the behaviour of Monoglycerides mixed with oils (particularly triglycerides), limited information is available regarding the phase behaviour of such systems. We have examined the phase behaviour of mixed saturated and unsaturated Monoglycerides1:1 (by weight) together with different oils systems. The main technique employed was X-ray diffraction, supplemented by optical microscopy, proton nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). Our results suggest that six phases (L2, α-gel phase, sub α- phase, β1 and oil crystallisation phase (β` for palm oil or β2 for miglyol oil or olive oil) were observed for G50/oil mixture. Furthermore, this paper proves that miglyol and palm oil incorporate into α-gel phase of G50. In contrast, olive oil dose not incorporate into α-gel phase of G50.
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gel phase lβ formation by mixed saturated and unsaturated Monoglycerides
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014Co-Authors: Abdullatif Alfutimie, Robin Curtis, Gordon J T TiddyAbstract:Abstract It is commonly thought that the α-gel phase (Lβ) consists of surfactant layers where the alkyl chains are mostly in the all-trans conformation and packed in a two dimensional hexagonal lattice with rotational disorder, but no translational mobility. We have examined the phase behaviour of mixed saturated and unsaturated Monoglycerides [glycerol monostearate (GMS) and glycerol monooleate (GMO)] to investigate whether gel phases will be formed from unsaturated Monoglycerides. In addition, this study examined the effect of aging on the phase behaviour of the mixture. An array of techniques was employed to investigate the phase behaviour as function of temperature: optical microscopy to observe optical textures, differential scanning calorimetry (DSC) to determine the transition enthalpies between phases, and nuclear magnetic resonance (NMR) to study surfactant mobility in the various phases. Additionally, we used small angle X-ray scattering (SAXS) to characterise the different mesomorphic phases at different temperatures. Finally, Fourier transform infrared spectroscopy (FTIR) was used to study the states of hydrogen bonding in the systems. Our results suggest that various phases for GMS/GMO mixture were observed α-gel (Lβ) phase, new α-gel (Lβ1) structure, β1 crystal phase, sub-α phase, β2-crystal, as well as an isotropic, L2, phase. Additionally there is some unsaturated monoglyceride incorporated into the α-gel phase of the saturated monoglyceride, which generated the new type of α-gel structure (Lβ1) characterised by a more disordered structural arrangement. GMO cannot pack in the same hexagonal structure as the α-gel phase of saturated lipids (Lβ). During storage, all monoglyceride structures transform to a highly ordered packing β crystal structure.
Rosa Garriga - One of the best experts on this subject based on the ideXlab platform.
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separation and profiling of Monoglycerides in biodiesel using a hyphenated technique based on high performance thin layer chromatography
Fuel, 2016Co-Authors: Carmen Jarne, Vicente L Cebolla, Luis Membrado, Javier Galban, Maria Saviron, Jesus Orduna, Rosa GarrigaAbstract:Abstract Monoglycerides are one class of impurities in biodiesel (BX) that can lead to deposits in engines. In this work, they have been separated as a compound class in BX from B5 to B100, using a hyphenated High-Performance, Thin-Layer Chromatography based technique on a unique silica gel plate. Hyphenation combines sequential steps of BX separation, densitometric detection of separated peaks, and on-line peak transferring to a mass spectrometer. A gradient separation was performed by Automated Multiple Development (AMD), followed by a post-chromatographic impregnation with primuline before densitometry detection. Therefore, chromatograms correspond to fluorescence detection by intensity changes (FDIC) of primuline in the presence of the components of BX. The final step of hyphenation has been an on-line transfer of the peak of Monoglycerides from the primuline-impregnated plate to an ESI mass spectrometer, using an elution-based interface. ESI-MS spectra provides unequivocal identification of Monoglycerides, and also a qualitative profiling of monoglyceride composition.