ABSTRACT:The aim of this work was to evaluate the impact of the moist heat sterilization process and the presence of ions in a dispersive medium on the rheological and textural characteristics of various hydrogels. Gelling agents from different groups were tested: synthetic polymers carbomers, alkylated carbomers, polycarbophil, poly(methylvinylether/maleic anhydride) decadiene crosspolymer; semisynthetic polymers methylcellulose, hydroxypropyl methylcellulose, sodium carboxymethylcellulose; and natural polymers iota and lambda carrageenans, xanthan gum, tragacanth, and agar. Hydrogel samples were prepared in purified water and buffer solution as well containing 25 mM succinic acid and 400 mM sodium chloride with pH 6.2. Samples were autoclaved at 121°C for 20 min. Their structural viscosity, hardness, compressibility, adhesiveness, and cohesiveness were evaluated before treatment, after treatment, and after 1 and 3 months of storage at 40°C. From all tested samples, the hydrogel with the most suitable properties as a carrier for the model protein, recombinant human thrombin, will be chosen. C 2015 Wiley Periodicals, Inc. Adv Polym Technol 2016, , 21543; View this article online at wileyonlinelibrary.com.
The aim of this work was to evaluate the effects of incorporating thrombin in arabinogalactan (AG)/β-glucan (BG)-based carriers. The products were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray powder diffraction (XRPD) and X-ray photoelectron spectroscopy techniques. Results, especially deconvoluted XRPD patterns indicated creation of new phases and potential complex formation. Results also highlighted that the AG carrier leads to higher residual thrombin-specific activity, while the in vivo haemostatic effect was enhanced when insoluble BG was present in the matrix. Our results confirm that thrombin can be successfully added to the carriers and that these materials are promising alternatives to standard vehicles.
The objective of this work was development and evaluation of gel-forming lyophilized formulation with recombinant human thrombin for topical administration. The influence of pH, ionic strength and buffer type on protein stability was evaluated as part of the pre-formulation screening studies. Results indicated an optimal pH from 6.0 to 7.0 and increased stability with increasing content of sodium chloride. The tested buffer types had no significant effect on thrombin stability. For further development, thermosensitive Pluronic® F-127 was employed as a bulking and gelling agent. Physical and mechanical characterization and viscosity measurement confirmed the gel-forming properties of the formulation at the application temperature of 32 °C. Several techniques (addition of well-soluble polyols, different freezing protocols and reconstitution under vacuum) were tested to decrease the reconstitution time. The obtained results revealed that a vacuum in the vial headspace is crucial for acceptable reconstitution. The freeze drying process has no negative impact on recombinant thrombin stability, and this was confirmed by reverse-phase-HPLC, activity assay and optical density measurements.
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