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At least 379 records · Page 21Linked to original sources
PubMed2003

pH-triggered release of macromolecules from spray-dried polymethacrylate microparticles.

PURPOSE: pH-triggered microparticles release their therapeutic payloads at acidic pH (e.g., in the phagosome), making intracellular drug delivery more efficient. Here we modify lipid-based microparticles that are safe and efficacious in nerve and brain and are potentially inhalable, making them pH-triggerable by incorporating an acid-soluble polymethacrylate, Eudragit E100 (E100). METHODS: Microparticles were produced by spray-drying and characterized by electron microscopy, Coulter counting, density measurement, and release kinetics of fluorescently labeled proteins. In addition, biocompatibility and cellular uptake were observed in rats. RESULTS: Microparticles were spheroids 3 to 5 microm in diameter with densities of 0.12 to 0.25 g/L. Microparticles with 20% (w/w) or more E100 demonstrated slow release of fluorescently labeled proteins at pH 7.4 but rapid release at pH 5. pH-triggerability was maintained for over 2 weeks in solution. Protein loadings of 0.2-20% (w/w) were pH-triggerable. Histologic examination of particles in rat connective tissue near nerve and muscle demonstrated biocompatibility aside from muscle edema in the cell layers adjacent to the particles and a localized inflammatory reaction with macrophages laden with microparticles. CONCLUSIONS: Microparticles containing E100 were pH-triggerable for many days and were taken up by macrophages, suggesting that they may be useful for intracellular drug delivery.

Acrylates↗
PubMed2002

Spray dried Eudragit microparticles as encapsulation devices for vitamin C.

The aim of the present paper was to study production of methacrylate microparticles for the delivery (administration) of ascorbic acid via the oral route. Vitamin C is an important antioxidant that may be involved in the reduction of the risk of certain types of cancer, such as colorectal cancer. As polymers different acrylic compounds were considered, namely Eudragit RL, L and RS. Spray-drying was used as preparation method of vitamin C/Eudragit microspheres. Microspheres were first characterized by size and morphology by scanning electron microscopy, then in vitro release kinetics by mean of dialysis method were studied. Although the produced microparticles were unable to slow down the release of the drug with respect to the free form of ascorbic acid, these microspheres showed a good morphology and size distribution that permit to propose them as candidate for the delivery of vitamin C as associated therapy in the treatment of colorectal cancer by oral route.

Antioxidants↗
PubMed2005

Spray-dried porcine plasma reduces the effects of staphylococcal enterotoxin B on glucose transport in rat intestine.

We investigated the intestinal transport of D-glucose (D-Glc) and 3 essential amino acids in a model of intestinal inflammation, and the effects of dietary supplementation with animal plasma proteins on this function. Wistar Lewis rats were fed a diet containing an isonitrogenous amount of milk protein (control group) or a diet supplemented with either spray-dried animal plasma (SDAP) or immunoglobulin concentrate (IC) from porcine plasma, from d 21 of life (weaning) until d 35. On d 30 and 33, rats were challenged intraperitoneally with Staphylococcus aureus enterotoxin B (SEB; groups SEB, SEB-SDAP, and SEB-IC) and on d 35, brush border membrane vesicles (BBMVs) were prepared and used for transport and binding studies. Administration of SEB reduced D-Glc transport across sodium glucose transporter 1 [SGLT1; 20% reduction in maximal transport rate (Vmax); P < 0.05], without affecting the Michaelis constant (Km). The results from specific phlorizin binding, Western blot, and immunohistochemistry supported the view that the effects of SEB are due to reduced expression of D-Glc transporters in the apical membrane. SEB increased the passive diffusion constant (Kd) for D-Glc 3-fold (P < 0.05). SEB did not affect mediated or passive amino acid fluxes of L-leucine, L-methionine, or L-lysine. Dietary SDAP increased the D-Glc Vmax in the SEB group without affecting the passive component. Changes in d-Glc Vmax due to SEB and to the dietary treatments were correlated with changes in the number of SGLT1 transporters present in the BBMVs (r = 0.9468; P < 0.05). Dietary IC had no observed effect. We estimate that, in rats challenged with SEB, SDAP supplementation can increase glucose absorption by 8-9% during the interdigestive periods.

Animals↗
PubMed2006

Degradation behaviour of microspheres prepared by spray-drying poly(D,L-lactide) and poly(D,L-lactide-co-glycolide) polymers.

Polymeric microsphere degradation must be taken into account in the design of drug delivery systems to be injected in in vivo systems, thus a prior analysis of in vitro degradation behaviour of microspheres appears to be necessary. In this study degradation characteristics of poly(lactide-co-glycolide) (PLGA) and poly(D,L-lactide) (PLA) microspheres prepared by the spray-drying technique have been examined. It was found that a slow decrease in molecular weight took place during the first stage of degradation, and the value of the rate constant decreased with the increase of the percentage of lactic acid of the polymer in a linear way. Thus, the period of time of this first stage decreased with the increase of content of glycolidyl units of the polymer, and it was the unique stage observed in PLA microspheres after 5 months of study. During this period of time, significant mass loss was not observed in the microspheres. The second stage of degradation of PLGA microspheres showed a larger rate constant, whose value increased with the content of glycolidyl units of the polymer. Mass loss was observed from number-average molecular weight about 6000. A sharp decrease of glass transition temperature (T(g)) was observed coinciding with the start of mass loss. This fact was accompanied by a physical change of the samples, fusion of microspheres to form large particles, which also fusion to form a unique mass of polymer; moment from that the degradation process was quicker.

Biocompatible Materials↗
PubMedDate not supplied

Determination of the presence of bovine immunoglobulin G in liquid or spray-dried porcine plasma and whole blood by agar gel immunodiffusion.

There is currently urgent interest in identifying the species of origin of the components of different animal by-products. In Europe, this interest is expected to increase with authorization of the re-introduction of these proteins into animal feed formulations. The number of validated methods to differentiate the species of origin for most of these products is limited. An easy, inexpensive, and accurate test was developed to determine the cross-contamination of bovine blood or plasma in porcine whole blood and plasma, both before and after spray drying. Agar gel immunodiffusion (AGID), the studied technique, detected the presence of bovine immunoglobulin G (IgG) in porcine plasma and in whole blood at inclusion levels >0.5% (v/v) in all cases. However, detectability was lower in liquid plasma (0.3%, v/v) and in liquid whole blood (0.5%, v/v). No differences were found when cross-contamination was simulated before or after whole blood centrifugation. The method described is reliable and inexpensive, and the samples are easy to prepare. Both minimal laboratory equipment and expertise are required for detection of bovine IgG in porcine blood products at inclusion levels of >0.5% (v/v).

Agar↗
PubMed2004

A novel spray-drying technique to produce low density particles for pulmonary delivery.

To date, all marketed DPI products rely on jet-milled, micronized drugs. Micronization often leads to drug powders exhibiting a large hydrophobic surface area resulting in strong cohesive forces, agglomeration and unsuitable aerosolization properties. In the current study, a new approach to prepare low density drug particles is described. Briefly, an oil-in-water emulsion consisting of an aqueous phase containing the dissolved model drug salbutamol sulphate, suitable surfactants, such as poloxamer or phosphatidylcholine, and optionally a bulking agent like lactose or a cyclodextrin derivative, and a lipid-phase that essentially consists of a liquefied propellant is spray-dried. By means of this process particles of very low density (0.02 g/cm3) and a drug load of 40% were prepared. The particle exhibit a porous to hollow structure, are thin-walled and of irregular shape. Depending on the composition of the aqueous phase, mean geometric particle sizes of <5 microm were obtained. It could be shown that a higher amount of poloxamer in the feed emulsion resulted in particles with improved dispersibility. Reducing the vapour pressure of the inner propellant phase by addition of dichloromethane decreased the agglomeration tendency of the powders as a result of the irregular particle morphology and, hence, resulted in higher fine particle fractions.

Administration, Inhalation↗