Solutions suspensions

Several polymerization techniques are in widespread usage. Our discussion is biased in favor of methods that reveal additional aspects of addition polymerization and not on the relative importance of the methods in industrial practice. We shall discuss four polymerization techniques bulk, solution, suspension, and emulsion polymerization. 

The vast majority of commercial apphcations of methacryhc acid and its esters stem from their facile free-radical polymerizabiUty (see Initiators, FREE-RADICAl). Solution, suspension, emulsion, and bulk polymerizations have been used to advantage. Although of much less commercial importance, anionic polymerizations of methacrylates have also been extensively studied. Strictiy anhydrous reaction conditions at low temperatures are required to yield high molecular weight polymers in anionic polymerization. Side reactions of the propagating anion at the ester carbonyl are difficult to avoid and lead to polymer branching and inactivation (38—44). 

Intravenous aqueous injections provide an excellent means of achieving a rapid therapeutic response. Parenteral product design, eg, vehicle and other excipient selection, as well as choice of route of adrninistration, can prolong therapeutic activity and increase onset times. Thus, oily solutions, suspensions, or emulsions can be adrninistered by subcutaneous or intramuscular routes to create prolonged effect, ie, depot injection (28). 

Polymerization Processes. Vinyl acetate has been polymerized industrially by bulk, solution, suspension, and emulsion processes (34). Perhaps 90% of the material identified as poly(vinyl acetate) or copolymers that are predominantly vinyl acetate are made by emulsion techniques. Detailed information is in patent and scientific Hterature and in procedures available in the brochures from monomer producing companies (15,34). 

Acrylate esters can be polymerised in a variety of ways. Among these is ionic polymerisation, which although possible (6—9), has not found industrial apphcation, and practically all commercial acryUc elastomers are produced by free-radical polymerisation. Of the four methods available, ie, bulk, solution, suspension, and emulsion polymerisation, only aqueous suspension and emulsion polymerisation are used to produce the ACMs present in the market. Bulk polymerisation of acrylate monomers is hasardous because it does not allow efficient heat exchange, requited by the extremely exothermic reaction. 

Although much less important in tonnage terms than processing in the molten and rubbery states, solution, suspension and polymerisation casting processes have a useful role in polymer technology. The main problem in such processes is to achieve a control of the setting of the shape once formed. 

Reaetion in gas, liquid (neat or in solution suspension/emulsion) or solid phase. 

The products are available as tablets, capsules, liquids (in the form of solutions, suspensions, emulsions, gels, or injectables), creams (usually oil-in-water emulsions), ointments (usually water-in-oil emulsions), and aerosols, which contain inhalable products or products suitable for external use. Propellants used in aerosols include chlorofluorocarbons (CFCs), which are being phased out. Recently, butane has been used as a propellant in externally applied products. The major manufactured groups include ... 

Block copolymerization is carried out by thermolysis of the macroinitiator in bulk, solution, suspension, or emulsion system. Further, it is possible to apply photolysis of azo group. In another case, an ionic active site coupled with an azo group is utilized [3]. 

Chain reactions are used to prepare a variety of high molar mass polymers of commericial importance and in practice may take one of four forms, namely bulk, solution, suspension, and emulsion methods. These four methods are described in the sections that follow, together with the loop modification which has become of commercial importance recently in producing latexes by emulsion polymerisation for the paint industry. 

Inhalation preparations— These can be solutions, suspensions, orpowders intended to be inhaled as aerosols for administration to the lung. 

One alternative method for preparing field fortifications solutions/suspensions is to prepare each fortification sample of each matrix in a separate mini-vial in the analytical laboratory and ship the vials to the field for use. This procedure precludes the use of pipets in the field and may be useful when Field Scientists not experienced in the use of pipets are involved in the field fortification process. One disadvantage of this procedure is that the mini-vials, if not designed correctly, will be hard to handle in the field, and surface tension of the suspension or fortification solution will tend to leave unacceptable amounts of the solution/suspension in the vial or at the lip of the vial and not on the matrix in question. This procedure may lead to cross-contamination of samples as the field fortification liquid is forced from the top... 

Many drugs are too unstable—either physically or chemically—in an aqueous medium to allow formulation as a solution, suspension, or emulsion. Instead, the drug is formulated as a dry powder... 

Behind the relatively straightforward compositional nature of ophthalmic solutions, suspensions, and ointments, however, lie many of the same physicochemical parameters that affect drug stability, safety, and efficacy, as they do for most other drug products. But additionally, specialized dosage forms present the ophthalmic product designer with some extraordinary compositional and manufacturing challenges. These... 

Because of these product sensitivities, most ophthalmic pharmaceutical products are aseptically manufactured and filled into previously sterilized containers in aseptic environments using aseptic filling-and-capping techniques. This is the case for ophthalmic solutions, suspensions, and ointments, and specialized technology is involved in their manufacture. 

Draft Guidance for Industry—Nasal Spray and Inhalation Solution, Suspension and Spray Drug... 

Aqueous products that are at greatest risk from microbial spoilage include solutions, suspensions, and emulsions for repeated oral, parenteral, or external use and include critical products such as multidose injections and eye drops. Unpreserved products without adequate antimicrobial efficacy should not be presented in containers intended for use on more than one occasion unless justified. When antimicrobial preservatives are used, their efficacy has to be demonstrated using the Ph Eur test for antimicrobial preservative efficacy. Factors to be taken into account in designing a preserved product include the nature of the preservative, its concentration in the product, the... 

Polystyrene is unusual among commodity polymers in that we can prepare it in a variety of forms by a diversity of polymerization methods in several types of reaction vessel. j Polystyrene may be atactic, isotactic, or syndiotactic. Polymerization methods include free radical, cationic, anionic, and coordination catalysis. Manufacturing processes include bulk, solution, suspension, and emulsion polymerization. We manufacture random copolymers ... 

The actual mathematical form of this function will depend upon the nature (i.e., the constitution ) of the particular material. Most common fluids of simple structure water, air, glycerine, oils, etc.) are Newtonian. However, fluids with complex structure (polymer melts or solutions, suspensions, emulsions, foams, etc.) are generally non-Newtonian. Some very common... 

Figure 13.2. Inorganic micro/nanoscale elements derived from wafers can be used to form solution suspensions for delivery to another substrate (e.g., plastic sheet) by casting processes (left frame), or they can be dry transfer printed in a way that preserves their lithographically defined spatial organizations (right frame).

Adjuvant—An oily substance that will form an emulsion aqueous solutions/suspensions of immunogen to enhance the antibody response. Complete adjuvant also contains Tubercele bacilli. 

Using antipyrine as a diagnostic tool, impacts of other chemicals or chemically uncharacterized solutions/suspensions may be assessable. 

Hu leuprolide acetate (human) 1209 Da Aerosol (MDI) Solution/ suspension 4-18% independent of formulation... 

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