Antigen sustained release

Sustained-release injections, subcutaneous and intramuscular, have been investigated in a variety of different formulations [217,218], Injections of degradable microspheres have efficiently prolonged delivery of numerous drugs [219-222], even antigenic substances and vaccines to produce immunity [223,224]. 

Marty and her colleagues (1978) pointed out that colloidal drug delivery systems were well suited for parenteral administration and may have use as sustained release products. Since gelatin is readily available, has low antigenicity, and has been utilized... 

As of today, there are no commercially available pharmaceutical products of this technology. The pharmaceutical industry however, is involved in developing nanoparticle-based delivery systems. Use of nanospheres to modify the blood-brain barrier (BBB)—limiting characteristics of the drug enables targeted brain delivery via BBB transporters and provides a sustained release in brain tissue and vaccine delivery systems to deliver therapeutic protein antigens into the potent immune cells are under investigation.103... 

Fiber-optic sensors based on controlled-release polymers provide sustained release of indicating reagents over long periods. This technique allows irreversible chemistries to be used in the design of sensors for continuous measurements. The sensor reported in this paper is based on a fluorescence energy transfer immunoassay. The sensor was cycled through different concentrations of antigen continuously for 30 hours. 

Khan, M.Z.I. Tucker, I.G. Opdebeek, J.P. Cholesterol and lecithin implants for sustained release of antigen release and erosion in vitro, and antibody response in mice. Int. J. Pharm. 1991, 76, 161-170. 

Antigen-rechallenged eyes treated with sustained-release dexamethasone also had less inflammation than control eyes and late complications including corneal neovascularization, cataract, and hypotony were less prevalent in treated eyes. A separate toxicity study also demonstrated that sustained-release dexamethasone was safe using clinical, electrophysiological, and histological parameters (12). 

Emulsions can also be used as sustained release products by reversing the nature of the emulsion from o/w to w/o. The i.m. injection of w/o emulsions of some water-soluble vaccines results in a slow release of the antigen, a greater antibody response and hence an immunity with longer duration. ... 

Compared to the evaporation procedure, extraction of organic solvent occurs relatively more rapidly, therefore, microspheres produced by solvent extraction are more porous usually resulting in faster release of drugs. Hence, for sustained release purposes, solvent evaporation is preferred. Solvent extraction could be more appropriate and effective compared to evaporation method for encapsulation of delicate and sensitive drugs such as proteins and peptides, enzymes, hormones, and antigens that are susceptible to thermal degradation at temperatures above room temperature (i.e.,... 

Use of cholesterol pellets for sustained release of protein antigens was recently examined by Opdebeeck and Tucker (1993). Utilizing matrices... 

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