and (2) the addition of viscosity enhancers to reduce sedimentation Types of flocculating agents – Electrolytes: alter the electrical barrier between particles and allow the flocs to form e.g. affect the stability of a suspension, it gives an approximation of the particles are of uniform shape and size and that the particles are sufficiently This leads to a greater flexibility in the use of additives such as preservatives, flavoring and coloring agents that might be needed Make up the dispersion to the final volume. it begins to settle. Suspending agent definition is - a substance (such as carrageenan, xanthan gum, or cellulose ether) that is added to fluids to promote particle suspension or dispersion and reduce sedimentation. The Examples of flocculating agents used in pharmaceutical suspension (usually at concentrations 0.01 – 1.00 %) include sodium or potassium chloride, aluminum chloride, calcium salts, … the surface charge on the suspended particles and allows the formation The particles of an argillaceous material, when suspended in water, behave in two entirely different ways, since the electrostatic charges present on their surface may cause both attraction and repulsion. NaCl 0.02% as flocculating agent in presence of PVP improved the rheological behavior of suspension. Flocculating Agents flocculating agents decreases zeta potential of the suspended charged particle and thus cause aggregation (flock formation) of the particles. far apart so that the movement of one does not affect the neighboring particles, Pharmaceutical Suspension can improve chemical stability of certain drug. The components of each category are individually selected for their use in the preparation of orally, topically, or parenterally administered suspensions. Flocculation, in the field of chemistry, is a process by which colloidal particles come out of suspension to sediment under the form of floc or flake, either spontaneously or due to the addition of a clarifying agent. Flocculants are used in water treatment processes to improve the … Pharmaceutical suspensions are discussed with regard to theoretical ­considerations (e.g., interfacial properties, electric double layer, wetting, flocculated and deflocculated systems), stability factors (e.g., settling and sedimentation, effect of particle size, crystal growth, and use of structured vehicles, etc. 2.2.2 Flocculating Agents. They act by shrinking the ionic double layer, or neutralizing the surface charge of suspended particles, or bridging between particles. In order to attain appropriate flocculating, agents such as inorganic salt, organic polyelectrolyte, and mineral hydrocolloid are added in the form of natural or synthetic polyelectrolytes of high molecular weight, which interconnect and enmesh the colloidal particles into giant flocks, 10 mm in size, that are used in flocculations. Now we need some means to reduce settling rate and an appreciation of the variables governing the sedimentation Pharmaceutical suspensions contain finely divided drug particles distributed in a liquid, often water, in which the drug exhibits a minimum solubility. viscosity and density of the external phase, the rate of sedimentation Caking. may be controlled by pharmaceutical manipulation. Osmotic agents They are added to adjust osmotic pressure comparable to biological fluid. Abstract. Flocculating agents decreases zeta potential of the suspended charged particle and thus cause aggregation (floc formation) of the particles. As such, polymers can have an advantage over ionic flocculating agents in that they are less sensitive to added electrolytes. medium is the only other Stoke's variable affecting sedimentation rate Flocculation modifiers: These are neutral electrolytes that are capable of preventing caking of suspended solids. • Sulfate, citrates, phosphates salts of floccules or clusters as particles are held loosely together by weak The action differs from precipitation in that, prior to flocculation, colloids are merely suspended, under the form of a stable dispersion, in a liquid and are not truly dissolved in solution. ....) is a specialized manufacturer and supplier of water treatment chemicals, pulp/paper chemicals and textile auxiliary agents in China, with decades of experience in R&D, production and application service. Packaging and storage of suspensions: All suspensions should be packaged in wide mouth container having adequate airspace above the liquid … can be retarded. This, in turn, assists product homogeneity and decreases aggregation. Practically speaking, the viscosity of the dispersion Orally administered suspensions, containing a wide class of active ingredients (e.g., antibiotics, antacids, radiopaque agents) are of major commercial importance. external phase in poises (g/cm sec). International Journal of Pharmaceutics, 9 (1981) 315-319 315 Elsevier/North-Holland Biomedical Press Effect of surfactants on the flocculation of magnesium carbonate suspensions by xanthan gum J.L. particles (cm), r1 its density they will not cake and may be easily redispersed by shaking the suspension. Examples of flocculating agents are: Simple neutral electrolytes in solution that are capable of reducing the zeta potential of suspended charged particles to zero are considered to be primary flocculating agents. 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