Microencapsulation process, use

The solvent evaporation microencapsulation process using sodium oleate as the emulsifier produced microspheres in high yields (75-95%), essentially free of agglomeration (1). Drugs with low solubility in water (0.02 mg/ml or less) e.g. thioridazine, were incorporated with 80-99% efficiency. Core loadings up to 60% were attained along with prolonged in vitro release. 

Shine AD, Gelb J Jr. Microencapsulation process using supercritical fluids. US patent 5766637, 1998. 

Enhancing Drug Release from Folylactide Microspheres by Using Base in the Microencapsulation Process... 

Hydroxypropyl cellulose is also used in microencapsulation processes and as a thickening agent. In topical formulations, hydroxypropyl cellulose is used in transdermal patches and ophthalmic preparations. ... 

Debenedetti and coworkers (88,89) provided one of the first examples of microencapsulation of a drug in the polymeric matrix. Richard and coworkers (90) provided a recent example of the microencapsulation process when they produced microparticles with the encapsulated model protein that showed sustained release. Foster and coworkers (87) also reported precipitation of copper-indomethacin by PVP with a 96-fold enhancement in the dissolution rate of indomethacin. These examples clearly demonstrated the advantages of using supercritical fluid processing for the preparation of polymer-drug formulations with potentially improved therapeutic properties. 

Regarding nucleation of solid particles from liquid droplets (antisolvent, nebulization, PGSS, microencapsulation processes), it is obvious that the droplets size is a basic parameter in the process. Some investigators reported results of experimental works supported by theoretical considerations on droplet formation by injection of a liquid into a pressurized fluid using a simple capillary nozzle (78) or a coaxial nozzle (79). Both articles, following previous works on liquid droplets formation into an insoluble liquid or into a gas, suggest the correlation of the experimental results with two dimensionless numbers... 

One of the main arms of high added value products is the development of properties that directly affect the safety and comfort of users. One of the ways to accomplish this is by using microencapsulation processes to impart new functionalities and properties to textiles (Anon, 2008). Thermochromic microencapsulated pigments bear the potential for medical application in terms of registering elevated body temperature of patients, thus allowing easier monitoring and point of care diagnosis. 

Zuidam, N. J. Shimoni, E., Overview of Microencapsulates for use in food products or processes and methods to make them. Encapsulation Technologies for Active Food Ingredients and Food Processing... 

Microencapsulation processes based on tlie solvent removal method have been reviewed in few book chapters and review articles "-" however, the current chapter presents classical expertize and essential old results, in addition to an up-to-date findings pertaining to this method, and the potential use of produced microparticles in the delivery of drugs to human. 

The coating material is an inert substance, which coats on core with desired thickness. Generally, hydrophilic polymers, hydrophobic polymers, (or) a combination of both are used for the microencapsulation process. The film thickness can be varied considerably, depending on the system. Surface area of the material to be coated and other physical characteristics of the coating materials used in microencapsulation methods are amenable, to some extent, to in situ modification. The list of a specific coating material is a lengthy. Table 47.1 provides the list of various polymers employed in microencapsulation. The typical coating properties such as cohesiveness, permeability, moisture... 

MC (methylene chloride) used as a solvent of PCL in a microencapsulation process for therapeutic protein by a nontoxic solvent belonging to Class 3. 

The efficiency of the microencapsulation process for the above described formulation was not evaluated because for this new formulation other experiments on the self-healing efficiency were carried out. This analysis does not require a hard-working procedure if we use the infrared spectroscopy by way of example, hereafter, in the section "Methodologies" we report a procedure to analyze the efficiency of the microencapsulation process for microcapsules only filled with DCPD. 

Controlled drug release properties are achieved through the application of coating to the surface of the capsule. A surface coating is applied in a microencapsulation process that frequently uses a plasticized aciylic copolymer. The type and concentration of plasticizer determines the rate of drag release. Trietltyl citrate is a typical plasticizer used in such microencapsulation. 

Numerous preparation technologies available for the encapsulation of core material have been reported [81,82,84]. The present discussion focuses on the different microencapsulation techniques that are more relevant to the coating industries, and also provides a comprehensive review of recently developed methods. In general, microencapsulation techniques are divided into two basic groups, namely chemical and physical, with the latter being further subdivided into physico-chemical and physico-mechanical techniques. Some of the important processes used for microencapsulation are summarized in Table 1.1. 

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