Showing papers on "Gelatin published in 1995"

Protein Release from Poly(lactic-co-glycolic acid) Microspheres: Protein Stability Problems

Abstract: The enzyme, carbonic anhydrase, has been incorporated within poly(lactic-co-glycolic acid) microspheres using a double emulsion and solvent evaporation technique. The protein stability problems during the microsphere formulation procedure and during the release period were examined in relation to the protein release kinetics over a 2 month period. Different protein release profiles could be obtained depending on the polymers used. The protein release kinetics exhibited an initial fast release followed by a slow release, resulting in an incomplete protein release although the microspheres degraded significantly. The very slow release kinetics were attributed to the protein aggregation and non-specific adsorption within the microspheres. It was found that the protein was significantly denatured and aggregated during the double emulsion formulation step. Several excipients such as albumin, poly (ethylene oxide), Pluronic F-127, and gelatin, which were loaded along with the protein within microspheres, demonstrated better protein release kinetics partly due to an increase in the protein stability. The released protein from these fast degrading microspheres, however, was severely hydrolyzed and lost its catalytic activity, caused by the accumulation of degradation products in the medium.

Collagen microparticles: Preparation and properties

Abstract: Collagen microparticles (CMPs) of diameters ranging from about 3 to 40 μm were prepared by the method of emulsifying and cross-linking native collagen. The particle size was mainly controlled by the molecular weight of the collagen used: an increase in denaturation of the collagen resulted in smaller particle sizes. Consequently, controlled denaturation is the best method to control the size of CMPs. Total denaturation results in the degradation product gelatin and subsequently yields very small nanoparticles with a minimum diameter of about 0.1μm. Collagen microparticles can be used as carriers for lipophilic drugs e.g. retinol, tretinoin, or tetracaine and lidocaine in free base form. Another feature of the biodegradable CMPs is their thermal stability, thus their sterilization can be readily achieved.

Preparation and characterization of crosslinked gelatin microspheres

Abstract: Gelatin, a natural macromolecule, is widely used in biomedical and biotechnological applications and is a good candidate for preparation of microspheres and microcapsules for the purpose of controlled release applications of drugs. In this study, gelatin microspheres crosslinked with glutaraldehyde with different crosslink densities were prepared by the phase separation technique induced by temperature change. The chemical structures of the microspheres were examined with FTIR and formation of crosslinks were observed. Topography, size, and shape of the microspheres were examined with scanning electron microscopy (SEM) and a narrow size distribution (approximately 1 μm) was observed. Thermal properties of microspheres were analyzed by differential scanning calorimetry and an increase in glass transition temperature values with an increase in crosslinking was observed. For each sample, dry and swollen densities of microspheres were determined by pycnometric methods and the average molecular weights between the crosslinks, Mc, were calculated from the equilibrium swelling experiments using the modified Flory-Rehner thermodynamic theory. A decrease in percent solvent content values with decreasing average molecular weight between the crosslinks was observed. © 1995 John Wiley & Sons, Inc.

Time‐intensity Measurement of Flavor Release from a Model Gel System: Effect of Gelling Agent Type and Concentration

Abstract: Flavor release from cornstarch, gelatin or iota carrageenan gels flavored with benzaldehyde, d-limonene or ethyl butyrate was measured at three gel strengths (soft, medium, firm) by 20 trained judges using the time-intensity (TI) method. At comparable gel strengths, starch and gelatin displayed greater flavor release properties than carrageenan, i.e., mean values for perceived maximum intensity (Imax) and total duration (Tdur) of flavor were higher for starch and gelatin than for carrageenan across flavors. Firm gelatin and carrageenan gels released flavor with a lower Imax than soft or medium gels, but Imax and Tdur did not vary across starch gel strengths. Results indicate both texture (firmness) and gelling agent affect flavor release from a gel.

Polyphenoloxidases immobilized in organic gels: Properties and applications in the detoxification of aromatic compounds.

Abstract: Gelatine gels originate from water in oil microemulsions in which the ternary system consists of isooctane/ sulfosuccinic acid bis [2-ethyl hexyl] ester/water; the solubilization of gelatin in the water pool of these microemulsions transforms them into viscous gels in which it is possible to cosolubilize various reactive molecules. These gels were used to immobilize two phenoloxidases, a laccase from Trametes versicolor and a tyrosinase from mushroom. The best balance between gel retention and catalytic activity was reached at a gelatine concentration of 2.5% (w/v) in the case of tyrosinase, while laccase immobilization was independent of gelatine concentration. Both enzymes kept the same optimum pH as the corresponding soluble controls, while a partial loss of activity was observed when they were immobilized. Immobilized enzymes showed an increased stability when incubated for several days at 4 degrees C with a very low release from the gels in the incubation solutions. The immobilization of tyrosinase and of laccase enhanced stability to thermal inactivation. Furthermore, gel-entrapped tyrosinase was almost completely preserved from proteolysis: more than 80% of the activity was maintained, while only 25% of the soluble control activity was detected after the same proteolytic treatments. A column packed with gel-immobilized tyrosinase was used to demonstrate that enzymes immobilized with this technique may be reused several times in the same reaction without loosing their efficiency. Finally, gel-entrapped tyrosinase and laccase were capable of removing naturally occurring and xeno-biotic aromatic compounds from aqueous suspensions with different degrees of efficiency. (c) 1995 John Wiley & Sons, Inc.

Biocompatible bioresorbable and non-toxic adhesive composition for surgical use

Abstract: The invention relates to a biocompatible, bioresorbable and non-toxic adhesive composition for surgical use, for the bonding, in particular, of biological tissues to one another or in an implanted biomaterial, characterized in that it comprises a reactive acidic solution of non-crosslinked and potentially crosslinkable collagen or gelatin modified by oxidative cleavage, at a concentration which is preferably between approximately 5 and 30 by weight. It also relates to reactive acidic solutions and powders based on non-crosslinked collagen or gelatin modified by oxidative cleavage which are used as intermediate products in the preparation of the above-mentioned composition, and to the process for their preparation. It also relates to adhesive kits which comprise, on the one hand, the above-mentioned reactive acidic solution and, on the other hand, a neutralizing solution and which are intended for extemporaneous mixing. Finally it relates to a method of application of the adhesive, composition according to the invention. The invention is particularly useful in the areas of adhesion, haemostasis, leaktightness with respect to liquids or gases, cicatrization, filling, avoiding adhesion in surgery, embolization, as a local system for release of medicamentary active principles, etc.

Investigation of pH‐sensitive drug delivery system of chitosan/gelatin hybrid polymer network

Abstract: A novel hydrogel based on a crosslinked chitosan/gelatin with glutaraldehyde hybrid polymer network was prepared. The gel swells in acidic medium and deswells in alkaline medium. A comparative study of the pH-dependent release of levamisole, cimetidine and chloramphenicol was carried out.

SANS studies of gelatin-surfactant interactions

Abstract: The structural perturbations that result from the interactions between the anionic surfactant sodium dodecyl sulfate and the biopolymer gelatin have been studied using small-angle neutron scattering In particular, contrast variation has been used to highlight the various components in the mixture We discuss these data in terms of structural changes associated with the individual components and their interactions with each other The effect of ionic strength on these structures is also considered

Gelatin use impairs platelet adhesion during cardiac surgery.

Abstract: Artificial colloids based on gelatin are used as plasma expander to replace donor blood products. In laboratory experiments, gelatin reduced both the velocity and extend of platelet agglutination by ristocetin, and only the agglutination velocity by polybrene (p These negative effects of gelatin on hemostasis were demonstrated in two clinical studies during cardiac surgery. In a randomized study of sixty patients undergoing cardiac surgery, gelatin as prime in the heart-lung machine appeared to result in diminished efficacy of aprotinin on hemostasis, whereas it did not affect hemostasis in non-aprotinin patients. An additional retrospective clinical study showed that only high dose of gelatin affected hemostasis. This suggests a limited role of plasma-vWF and a strong back-up mechanism of platelet-vWF in achieving hemostasis.

Cross‐Linking of Gelatin Capsules and Its Relevance to Their in vitro‐ in vivo Performance

Abstract: The present review deals with the chemistry of gelatin cross-linking under conditions that are relevant to pharmaceutical situations. Mechanistic rationalizations are offered to explain gelatin cross-linking under "stress" conditions. These include elevated temperature and high humidity conditions. In addition, the chemical interactions between gelatin and aldehydes, such as formaldehyde and other formulation excipients, are discussed. The literature on the in vitro and in vivo dissolution and bioavailability of a drug from stressed gelatin capsules and gelatin-coated tablets is reviewed. Cross-linking phenomena, occurring in stressed hard gelatin capsules and gelatin-coated tablets, could cause considerable changes in the in vitro dissolution profiles of drugs. However, in a few cases, the bioavailability of the drug from the stressed capsules is not significantly altered when compared to that obtained from freshly packed capsules. It is concluded that, as with other drug-delivery systems, careful attention should be paid to the purity and chemical reactivity of all excipients that are to be encapsulated in a gelatin shell. It is suggested that in vitro dissolution tests of hard gelatin-containing dosage forms be conducted in two stages, one in a dissolution medium without enzymes and secondly in dissolution media containing enzymes (pepsin at pH 1.2 or pancreatin at pH 7.2, representing gastric and intestinal media, respectively) prior to in vivo evaluation. Such in vitro tests may constitute a better indication of the in vivo behavior of gelatin-encapsulated formulations. Furthermore, testing for contamination with formaldehyde as well as low molecular weight aldehydes should be a standard part of excipient evaluation procedures.

Determination of moisture in intact gelatin capsules by near-infrared spectrophotometry.

Abstract: Pharmaceutical application of near-infrared spectrophotometry offers rapid, nondestructive, and noninvasive techniques to analyze samples. the analytical power of near-IR spectrophotometry is derived from the computerized analysis ofcomplex spectra with overlapping bands, and advances in computer algorithms allow increasingly detailed analysis of samples nondestructively. Recent examples of pharmaceutical near-IR spectrophotometry include the anal sis of degradation products (I). the detection of tampering in tablets and capsules (2,3) and moisture determination (4). As for moisture, it has been noted that gelatin in capsules undergoes conformational change and cros'linking when scored under high humidity conditions, as demonstrated h' etodolac (5), gemfibrozil (6), hydrochlorothiazide (6), and diphenhydramine hydrochloride capsules (6', and by gelatincoated acetaminophen tablets (7). The crosslinking process in gelatin causes formation of a swollen, rubbery, water insoluble gelatin (pellicle) resulting in reduced in vitro dissolution rates oidrugs (8,9,10). Apparently this water insoluble gelatin film tpcllicle) acts a barrier, restricting drug release. It has been proposed that the mechanism by shich humidity acts is through indirect catalysis of imine formation, which is the first intermediate in most gelatin crosslinking reactions (II). The b-amino functions of the lysine reidues from the polypeptide backbone of gelatin have been \ implicated in the crosslinking reaction, which occurs after prolonged exposure ofgclatin capsules to humidity and heat. Several reactions involving imine intermediates have been suggested to take place during the crosslinking process of' gelatin (II). The effect of crosslinking in gelatin capsules on in ri'o bioavailahility is being studied (5,7,12), and the determination of moisture levels in intact gelatin capsules using a convenient and noninvasive method, such as near-IR spectrophotometry is a genuine advantage. The coupling of fast computer algorithms with near-IR spectrophotometers should allow real-time analysis and zero-defect quality control of capsules on pharmaceutical production hues. MATERIALS AND METHODS

Procedure for encapsulating ibuprofen

Abstract: This disclosure is directed to preparation of individual taste-masked, high bioavailability, high payload, microcapsules by microencapsulation of water-insoluble NSAID drug materials in the substantial absence of microcapsule agglomerates. These taste-masked microcapsules contain a high payload, e.g., about 83+wt. % of said NSAID drug material having high bioavailability and can then be formulated into chewable tablets and liquid aqueous suspensions for medicinal use. Both cellulose acetate phthalate and gelatin are the microencapsulating polymer wall material. Control of pH, controlled addition of a Hofmeister (lyotropic) salt, microencapsulation of the water-insoluble NSAID medicament with a liquid phase of both cellulose acetate phthalate and gelatin microencapsulating material and the subsequent insolubilization of said liquid encapsulating material after it is wrapped around the medicament core with dilute acid are important process parameters to achieving the proper individual microcapsules to obtain highly bioavailability taste-masked, water-insoluble NSAID drug materials, esp., naproxen and ibuprofen, by microencapsulation alone.

Method of encapsulating food or flavor particles using warm water fish gelatin, and capsules produced therefrom

Abstract: This invention is directed to a method of forming microencapsulated food or flavor capsules as well as the capsules produced by the method. The method includes providing food or flavor particles to be encapsulated, and forming a mixture of a warm water fish gelatin and the food or flavor particles in aqueous media. The method further includes microencapsulating the particles with the gelatin at elevated temperatures by complex coacervation to form the microencapsulated capsules. If desired, the method may further include the step of separating the capsules. In a preferred form, the method is conducted at a temperature of about 33 °C to about 35 °C. Preferably, the warm water fish gelatin used in the encapsulation method has a bloom of from about 150 to about 300 bloom, more preferably from about 250 to about 300 bloom. Many different kinds of food or flavor particles may be used, such as for example, vegetable oil, lemon oil, garlic flavor, apple flavor or black pepper. The invention also is directed to the food or flavor capsules produced by the method.

Soft gelatin capsule compositions

Abstract: The present invention relates to improved pharmaceutical compositions containing an analgesic encapsulated within a soft gelatin shell wherein said shell contains a xanthine derivative, such as caffeine.

Interactive Precipitation Between Phenolic Fractions and Peptides in Wine-Like Model Solutions: Turbidity, Particle Size, and Residual Content as Influenced by pH, Temperature and Peptide Concentration

Abstract: Four gelatin preparations (whole gelatin of average MW 70 000 and gelatin peptides of average MW 10 000, 5000, and 2000), three synthetic peptides (MW 2531, 1354, and 1274) composed of a repeating sequence of amino acid residues (proline, proline or hydroxyproline, and glycine), and soluble and insoluble polyvinylpyrrolidone were used. They were mixed with four phenolic fractions (dimeric, oligomeric, polymeric, and total phenol fractions from grape seeds) in aqueous 10% ethanol solutions of pH 2.5 to 4.0. After four days at 4°C, 15°C, or 25°C, the turbidity, residual phenol and peptide contents, and particle sizes of the precipitates formed in the mixtures were determined. The turbidity increased with increasing particle size and with decreasing residual phenol and peptide. Increasing the pH from 2.5 to 3.0 - 3.3 (depending on the phenolic fraction) or lowering the storage temperature resulted in increased turbidity and decreased residual phenol and peptide, but the degrees of the changes in turbidity and residual contents varied with the phenolic fraction. Increasing the amounts of large MW whole gelatin and the 2000 MW gelatin peptide from 25 to 150 mg/L resulted in increasing turbidity, increasing particle size, and decreasing residual phenols. The turbidity with the small gelatin peptide was higher than that with the large gelatin below pH 3.0 to 3.3, but above these pH values the turbidity with the latter was larger than that with the former. The phenol adsorption capacity of the small synthetic peptides was higher than that of large MW whole gelatin or the other gelatin preparations when added at the same weights, but other effects were similar. The results on the interaction between the small peptides and the phenolic fractions showed that the gelatin peptides and the synthetic peptides of low molecular weight were very effective for fining wines, at least at the same levels as whole gelatin or soluble polyvinylpyrrolidone with high affinity for phenols. The mode of association for phenol-peptide interaction and the properties of peptide chains effective for the adsorption of phenols are discussed.

Absorption of Insulin Using Water-in-Oil-in-Water Emulsion from an Enteral Loop in Rats

Abstract: The present work was undertaken to prepare water-in-oil-in-water (W/O/W) emulsions as a carrier for insulin via the enteral route. The emulsions were prepared by a two-step procedure using a homogenizer. To avoid insulin escape from the inner aqueous phase, 3, 5 or 10% gelatin was added in the inner phase. The oily phase was composed of 5% lecithin, 20% Span 80 and 75% soybean oil. The purified water containing 3% Tween 80 was used for the outer aqueous phase. In addition, these emulsions were filtered with a membrane filter (0.45 μm) to obtain smaller emulsion particles. The stability of the emulsions was evaluated by a turbidity measurement method and photomicrographic observation. By the addition of gelatin to the inner aqueous phase and storage at 4°C, the stability of the emulsions could be improved. The hypoglycemic effects of insulin after administration of emulsion to the stomach, the duodenum, the jejunum, the ileum and the colon were examined using an in situ loop method in rats. A significant hypoglycemic effect was observed at the ileum and colon loops after administration of the filtered emulsions containing 5% gelatin in the inner phase. These findings suggest that the W/O/W multiple emulsions stabilized by gelatin can improve ileal and colonic absorption of insulin.

Capsule shell compositions and their use

Abstract: A capsule shell is formed of a composition comprising 18-28 parts by weight of hydroxypropylmethyl cellulose whose 2% aqueous solution has a viscosity of 2.4-5.4 centistokes at 20°C as a base, 0.01-0.1 part by weight of carrageenan as a gelling agent, and 0.05-0.6 part by weight of a potassium and/or calcium ion as a co-gelling agent. The capsule shell exhibits disintegrating ability equivalent to gelatin shells without losing that ability even under special conditions, in particular a high concentration of calcium ions.

The role of gelatin in paper permanence

Abstract: In William Barrow's classic study (1974) of historical paper specimens, he examined a number of factors that affect the stability of naturally aged papers, including cellulose fiber purity, alum content, amount of alkaline carbonate reserve, and pH. Barrow did not, however, investigate the effect of gelatin levels in his papers, and others have undertaken only limited research on the topic. In the study reported here, 40 historical paper specimens were analyzed to determine their gelatin content. Data from measurements of L* light-to-dark values, surface pH, and calcium content were compared with gelatin content. The data provided by these analyses show that both the appearance and the permanence of the papers may be affected by their gelatin content; avenues of further investigation in this area are outlined.