Formulation suspension

Pinocytosis. This process by which particles are absorbed can be an important factor in the ingestion of particulate formulations of chemicals (e.g., dust formulations, suspensions of wettable powders, etc.) however, it must not be confused with absorption by one of the above processes, where the agent has been released from particles. 

The every-12-hour regimen is associated with significantly less diarrhea however, the 200 and 400 mg formulations (suspension and chewable tablets) contain aspartame and should not be used by phenylketonurics. 

One of the problems faced in formulating suspensions is that finely divided particles are not easily wetted in water. This may be the result of the hydrophobic nature of the drugs and/or entrapped gases (i.e., air). The wetting process is the displacement of one fluid by another from the solid surface. When wetting solids, the entrapped... 

EC emulsifiable concentrate, M = microencapsulated formulation (suspension), R F = residual formulation (dry powder). 

With proper selection of raw materials which do not require pulverization, it is possible to formulate suspensions for high production with minimum process time. 

There are two types of MDI formulations suspension formulations, in which microparticulate drug (typically micronized material) is dispersed in... 

Formulations Suspension concentrate, emulsifyable concentrate, wettable powder mixed formulations with Petroleum oils. 

The pressurized metered dose inhalers in the use of environmentally friendly propellants means the choice of hydrofluoroalkanes, wherein the dosage form can be a suspension of the solution form. The problems of formulating suspensions, as discussed earlier, apply here as well, but particularly with respect to interactions with the formulation components specific to pressurized inhaler systems. 

Figure la-c shows the dependence of the apparent viscosity of the enzyme hydrolysis suspension on biomass concentration. It clearly demonstrates a dramatic decrease of viscosity at the reloading point (i.e., after the initial 4 h). The experimental determination of the viscosity-shear rate and shear stress-shear rate relationships of the various formulation suspensions with different concentrations was performed with a variable speed rotational viscometer (2 to 200 rpm). 

A well-formulated suspension is second to a solution in efficiency of absorption. Dissolution is the rate-limited factor in absorption of a drug from a suspension. However, drug dissolution from a suspension can be rapid if very fine or micronized powders are used. (These have a larger surface area or specific surface.)... 

Drugs formulated in tablet and capsule dosage forms may not achieve the state of dispersion in the G1 tract that is attainable with a finely subdivided, well-formulated suspension (Fig. 9.2). 

Magnesia and aluminum suspension is useflil for the therapy of duodenal ulcers when given at high doses at frequent intervals. It is available in both hquid and tablet formulations. 

Applications. The high heat tolerance and good salt compatibiUty of welan gum indicate its potential for use as an additive in several aspects of oil and natural gas recovery. Welan also has suspension properties superior to xanthan gum, which is desirable in oil-field drilling operations and hydraulic fracturing projects. It is compatible with ethylene glycol, and a welan—ethylene glycol composition that forms a viscous material useful in the formulation of insulating materials has been described (244). 

The characteristics of interior paints that require testing and analysis include hiding and appearance, package stabiHty, adhesion, spatter resistance, flow and leveling, color and sheen uniformity, touch-up, stain removal, burnish resistance, and block and print resistance. A popular test that assesses the wet abrasion resistance of an interior paint is to measure its scmb resistance. A mechanical device is used to scmb a paint film of a specified thickness with a standard bmsh and abrasive cleanser suspension. The number of scmb cycles (back and forth movements of the weighted bmsh) at various end points (first cut through, or 50% removal of the film) is then recorded. Scmb resistance usually holds steady or decreases slightly as PVC is increased, but drops quickly once the CPVC is exceeded in a paint formulation. 

Patents have appeared (33,34) which show formulations containing PMMA emulsion polymer and PMMA suspension polymer combined with benzyl butyl phthalate and octyl benzyl phthalate. It is likely that polymers of this type will require highly polar plasticizers in order to have both adequate compatibiHty and adequate gelation. When replacing PVC appHcations the use of large quantities of phosphate plasticizers is sometimes required to give equivalent fire performance. 

Because the regions of the alimentary tract vary widely ia pH and chemical composition, many different commercial formulations of barium sulfate are available. The final preparations of varyiag viscosity, density, and formulation stabiUty levels are controlled by the different size, shape, uniformity and concentration of barium sulfate particles and the presence of additives. The most important additives are suspending and dispersiag agents used to maintain the suspension stabiUty. Commercial preparations of barium sulfate iaclude bulk and unit-dose powders and suspensions and principal manufacturers are E-Z-EM (Westbury, New York), Lafayette-Pharmacol, Inc. (Lafayette, Indiana), and Picker International, Inc. (Cleveland, Ohio). 

A classification by chemical type is given ia Table 1. It does not attempt to be either rigorous or complete. Clearly, some materials could appear ia more than one of these classifications, eg, polyethylene waxes [9002-88 ] can be classified ia both synthetic waxes and polyolefins, and fiuorosihcones ia sihcones and fiuoropolymers. The broad classes of release materials available are given ia the chemical class column, the principal types ia the chemical subdivision column, and one or two important selections ia the specific examples column. Many commercial products are difficult to place ia any classification scheme. Some are of proprietary composition and many are mixtures. For example, metallic soaps are often used ia combination with hydrocarbon waxes to produce finely dispersed suspensions. Many products also contain formulating aids such as solvents, emulsifiers, and biocides. 

Sahcyhc acid USP, EP, and other pharmacopeia grades are used medically as antiseptic, disinfectant, antifungal, and keratolytic agents. Sahcyhc acid is formulated in lotion or ointment formulations for the treatment of dandmff, eczema, psoriasis, and various parasitic skin diseases. Because the keratolytic property of this aromatic acid has use in the safe removal of dead skin cells from the surface of healthy skin, the acid is used in concentrated sahcyhc acid solutions or suspensions to remove warts and corns. In more dilute form, sahcyhc acid preparations have found use in dandmff and eczema treatment. Sahcyhc acid has been considered and found effective by the Advisory Committees to the FDA in various over-the-counter (OTC) dmg regulated uses. Among these are acne products, dermatitis, dry skin, dandmff and psoriasis products, and foot care products (24). 

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