Excipient microencapsulation

Phase separation microencapsulation procedures are suitable for entrapping water-soluble agents in lactide/glycolide excipients. Generally, the phase separation process involves coacervation of the polymer from an organic solvent by addition of a nonsolvent such as silicone oil. This process has proven useful for microencapsulation of water-soluble peptides and macromolecules (48). 

Excipients used in the formulation usually include a mixture of a water-soluble polymer and a crystalline sugar. Mannitol and natural polysaccharides such as gelatin and alginates are used. Microencapsulation and complexation with ion exchange resins can be combined with additional flavors and sweeteners for taste masking of bitter drugs. The fairly complex nature of manufacture and scale-up contributes to... 

Morlock, M., Koll, H., Winter, G., and Kissel, T. (1997), Microencapsulation of rh-erythropoietin using biodegradable poly(D,L-lactide-co-glycolide) Protein stability and the effects of stabilizing excipients, Ear. I. Pharm. Biopharm., 43, 29-36. 

The formation of inclusion complexes of lipids inside the amylose helix is not the only important factor regulating the functional properties of foodstuffs. The adsorption of lipids on starch surfaces can prevent the separation of components in frozen starch noodles. Such surface sorption reduces the viscosity and adhesiveness of the starch.888 The latter property can also be important in the microencapsulation of medicines. For example, a complex of cornstarch with glucolipids has been patented as an excipient for 3-(p-chlorobenzyl)-6-methoxy-2-methylindole-l-acetic acid.889... 

For polymorphic compounds, such as sulfa drugs, talc excipients induced polymorphic transformation of sulfamethoxazole during the process of microencapsulation by spray-drying,... 

Exposure to w/o interfaces Reducing or avoiding denaturation at w/o interfaces by including protective excipients/ employing anhydrous microencapsulation processes. 

Law MFL, Deasy PB. Effect of common classes of excipients on extrusion-spheronization. / Microencapsul 1997 14(5) 647-657. 

Light mineral oil is used in applications similar to those of mineral oil. It is used primarily as an excipient in topical pharmaceutical formulations where its emollient properties are exploited in ointment bases see Table I. It is also used in ophthalmic formulations. Light mineral oil is additionally used in oil-in-water and polyethlylene glycol/gylcerol emulsions as a solvent and lubricant in capsules and tablets as a solvent and penetration enhancer in transdermal preparations and as the oily medium used in the microencapsulation of many drugs. ... 

In the anhydrous microencapsulation, protein and excipients were suspended/dissolved in PLA/acetonitrile solution and then added to cottonseed oil to form an o/o emulsion with Span 85 as an emulsifier. Petroleum ether was then added to extract the acetonitrile and the microspheres were hardened. The microspheres were then recovered by filtration and dried under vacuum. As shown in Table 5 and Fig. 5, without the pore-forming PEG, only 36% BSA was released from PLA microspheres in 1-month of incubation with a total recovery (released-fall soluble and aggregated residue in polymer after release) of 76%. Blending in 30% of 35 kDa PEG with the PLA eliminated the BSA aggregation in polymer completely, with 82% of encapsulated BSA released in 1 month. The improved BSA stability in PLA/PEG microspheres could be attributed to a less acidic and more hydrophilic microenvironment in the polymer. As seen in Fig. 6, unlike PLGA 50/50, which caused a dramatic pH drop in the release medium after a 4-week incubation (41), a relatively neutral pH was retained in the release medium for both PLA and PLA/PEG microspheres. A slightly lower pH in the release medium incubated with PLA/PEG microspheres relative to that in PLA was also... 

The potential of other coat materials for alginate microcapsules was also discussed. In order to advance the science of probiotic microencapsulation, it is important to use new polymers as encapsulation matrices or coating materials and to add excipients into the matrices with a view to increase the protection of bacteria and to reduce the production costs. 

The development of a stable protein formulation for microencapsulation also includes consideration of the potential for protein-polymer interactions. For example, proteins that are very basic (high PI) may interact with the free acid groups generated by the degradation of polylactides. In this case, it may be necessary to add excipients such as polyionic compounds (anionic for protein binding, cationic for polymer binding) that prevent or reduce the interaction between the protein and the polymer. For polylactides, it may be unlikely that the protein will form a covalent adduct with... 

Encapsulation involves the incorporation of active ingredients such as flavors, enzymes, cells or other materials in small capsules. The choice of excipients for encapsulation is very important for the encapsulation efficiency and protein stability within the matrix. Applications of this technique have increased in the food and pharmaceutical industries since the encapsulated materials can be protected from moisture, heat or other extreme conditions. Thus their stability is improved and their viability maintained. Powder formation can lower the water activity of the material, the reactivity and the diffusivity of encapsulated compounds, and the diffusivity of residual water. In the food industry microencapsulation is often associated with the already discussed retention of flavor compounds during drying and storage. In pharmaceutical applications, the purpose of microencapsulation is to control the release and improve the bioavailability of active ingredients. 

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