[Diffusion of sulfathiazole and sulfanilamide in polyethyleneglycol excipients. III. Diffusion of dissolved active substances in pharmaceutical solid and liquid systems].
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Ointments↗
Biomedical subjects
V Zecchi
Publications and source records attributed to V Zecchi.
[Microscopic determination of the coefficient of diffusion of salicylic acid in excipients for ointments].
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Emulsions↗
[Proposed method for softening time of tablets containing rice starch and its use in the quantitative evaluation of the activity of a disaggregating agent].
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Hardness Tests↗
[Influence of various types of starch on the softening time of tablets II].
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Hardness Tests↗
[Diffusion model for the evaluation of drug-vehicle interactions in ointments. I. Diffusion of ethyl p-aminobenzoate in a polyethylene glycol excipient].
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Benzocaine↗
[Synthesis of bis-homoanalogues of nucleosides].
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Magnetic Resonance Spectroscopy↗
Fatty acid substituted polyvinyl alcohol as a supporting material for microsphere preparation.
Polyvinyl alcohol, substituted with lauric, myristic, palmitic, and stearic acids at different substitution degrees was employed for the preparation of biodegradable microspheres containing progesterone or indomethacin. A solvent extraction/method was followed, starting from an oil-in-water dispersion containing the polymer and drug in the inner phase. Microspheres were obtained with high loading efficiency, whose release properties were dependent on the nature of the acyl substituent and the substitution degree. Kinetics approaching zero-order were obtained for the most hydrophile microspheres such as those based on the least substituted polymers and lowest molecular weight substituents. The hydrophilicity of these systems hindered protein absorption on their surface, suggesting their suitability for parenteral use.
Adsorption↗
Controlled release of vancomycin from freeze-dried chitosan salts coated with different fatty acids by spray-drying.
The aim of this study was to describe a controlled drug release system based on chitosan salts for vancomycin hydrochloride delivery. Chitosan aspartate (CH-Asp), chitosan glutamate (CH-Glu) and chitosan hydrochloride (CH-HCl) were prepared by freeze-drying and coated with stearic, palmitic, myristic and lauric acids by spray-drying technique. Vancomycin hydrochloride was used as a peptidic model drug whose sustained release should minimize its inactivation in the upper part of the gastrointestinal tract. This study evaluated, in vitro, the influence of chitosan salts on the release behaviour of vancomycin hydrochloride from the freeze-dried and spray-dried systems at pH 2.0 and 7.4.
Anti-Bacterial Agents↗
Poly(vinylalcohol-co-vinyloleate) for the preparation of micelles enhancing retinyl palmitate transcutaneous permeation.
The amphiphilic properties of poly(vinylalcohol) substituted with oleic acid was evaluated to assess the possibility to prepare polymeric micelles in an aqueous phase containing a hydrophobic core able to host lipophilic drugs such as retinyl palmitate and thereby enhance its transcutaneous absorption in the stratum corneum. The effect of the increased drug absorption suggests the possibility of interaction between the substituted polymer and the components present in the intercorneocyte spaces. Correlations between the drug concentration in the preparative mixture, micelle size, and drug permeation were evaluated to establish the best functional properties of the micellar systems enhancing retinyl palmitate absorption. Transcutaneous absorption increased with decreasing micelle size, and micelle size decreased on decreasing the drug concentration in the preparative mixture.
Administration, Cutaneous↗
Bovine serum albumin nanospheres carrying progesterone inclusion complexes.
Bovine serum albumin nanospheres carrying cyclodextrin complexes for the delivery of progesterone were produced. Inclusion complexes composed of progesterone and hydroxypropyl-beta-cyclodextrin or dimethyl-beta-cyclodextrin were prepared by spray-drying or freeze-drying methods. Prog alone and its inclusion complexes were incorporated into bovine serum albumin nanospheres using a coacervation method and cross-linking with heating. The nanosphere suspensions were essicated by spray-drying or freeze-drying. The inclusion complexes and the nanospheres were characterized by Fourier Transform-Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC). Phase-solubility diagrams and stability constants were determined in distilled water at different temperatures (10, 25, and 37 degrees C). Size of nanospheres, their drug loading capacity and swelling ability were evaluated, as well as the in vitro controlled release profiles at pH 5.5 and 7.4.
Calorimetry, Differential Scanning↗
Micelles based on polyvinyl alcohol substituted with oleic acid for targeting of lipophilic drugs.
Polymeric micelles based on polyvinyl alcohol substituted with oleic acid were used as vehicles for progesterone and folic acid. The ability of this amphiphilic polymer to entrap lipophilic drugs and to generate stable micelles in aqueous neutral medium makes it a good candidate for drug delivery. The release of the loaded drugs in acidic environments represents another important property of these systems. Size of micelles, their stability, and their drug-loading capacity were evaluated, as well as the in vitro controlled-release profiles at pH 7.4 and 5.5.
Drug Delivery Systems↗
Crosslinked poly(methyl vinyl ether-co-maleic anhydride) as topical vehicles for hydrophilic and lipophilic drugs.
Poly(methyl vinyl ether-co-maleic anhydride) crosslinked with ethylene glycol (GZ-ET), 1,4-butanediol (GZ-BUT), 1,6-exandiol (GZ-EX), 1,8-octanediol (GZ-OCT), 1,10-decanediol (GZ-DEC) or 1,12-dodecanediol (GZ-DOD) was prepared and employed as a supporting material for aqueous topical gels containing pyridoxine hydrochloride (PYCL) chosen as a hydrophilic model molecule or for O/A emulsion containing beta-carotene chosen as a hydrophobic model molecule. We analyzed the effect of the nature of the crosslinker on the permeation of hydrophilic and lipophilic vitamins through porcine skin by in vitro permeation studies. The vehicles formed by crosslinked poly(methyl vinyl ether-co-maleic anhydride) showed enhanced vitamins permeation with respect to the same vehicles formed by noncrosslinked poly(methyl vinyl ether-co-maleic anhydride) (GZ). The decrease in the crosslinker acyl chain length provides vehicles accelerating the drug permeability through the skin.
Administration, Topical↗
Indomethacin loaded chitosan microspheres. Correlation between the erosion process and release kinetics.
The preparation of chitosan microspheres covalently linked with citric acid and loaded with indomethacin is described. The release kinetics correlated with the concentration of chitosan in the microsphere preparative mixture and the pH of the release medium. Deviations from Fickian to zero order kinetics were observed at higher concentrations of chitosan and at pH 7.4. The variations induced by these parameters on drug diffusion and solubility in the matrix undergoing erosion were analyzed.
Anti-Inflammatory Agents, Non-Steroidal↗
Chitosan microcapsules as controlled release systems for insulin.
This study analyses the use of chitosan for the production of surface crosslinked microparticulate systems containing insulin. The microcapsules were prepared by an innovative technique based on interfacial crosslinkage of different amounts of chitosan solubilized in the inner phase of a water/oil emulsion by means of ascorbyl palmitate. The correlation between the main formulation parameters and the functional properties of the microcapsules were analysed. Insulin is incorporated with high efficiency. The peptide release is constant for appreciable periods of time. The content of chitosan modulates the main physico-chemical properties of the matrix.
Biocompatible Materials↗
Influence of physico-chemical parameters on the release kinetics of ketoprofen from Poly(HEMA) crosslinked microspheres.
This report analyses the release of Ketoprofen from Poly(HEMA) microspheres crosslinked with EGDMA at different crosslinking ratios and loaded by soaking in saturated solutions of the drug. Release appears to be influenced by the dissolution of Ketoprofen in the hydrogel and it is strictly correlated with the diffusibility of the drug in the gelled matrix. The release rate of the drug in the hydrogel rises with the increase in the diffusional conductance and the release kinetics approaches zero order particularly at the higher values of the diffusional conductance.
Cross-Linking Reagents↗
Laminar flux apparatus for dissolution studies of solid pharmaceutical formulations: a proposal.
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Chemistry, Pharmaceutical↗
Microparticles of BSA substituted with deoxycholic acid and triethylene glycol glutarate. Correlations between the physico-chemical properties of the matrix and the release kinetics.
Bovine serum albumin or bovine serum albumin covalently linked to deoxycholic acid and triethylene glycol glutarate were used for the preparation of microspheres loaded with indomethacin. The presence of these residues on the bovine serum albumin molecule increased the loading levels. The kinetic analysis of release evidenced a zero order release period from the start of release in the microparticles obtained by bovine serum albumin linked to deoxycholic acid and triethylene glycol glutarate, followed by a decreasing rate release and a first Anomalous period followed by a zero order period in the albumin microparticles. These different release behaviours were correlated to the modifications induced by deoxycholic acid and triethylene glycol glutarate on the drug diffusivity and solubility in the matrix undergoing erosion.
Chemical Phenomena↗