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flocculating agents in pharmaceutical suspensions

Flocculating Agents flocculating agents decreases zeta potential of the suspended charged particle and thus cause aggregation (flock formation) of the particles. In suspensions, a liquid and an insoluble solid meet to form an interface. Flocculating agents are electrolytes which carry an electrical charge The formulation of a pharmaceutical suspension requires careful consideration of how to ensure homogeneous drug distribution during administration. Buffers and pH adjusting agents They are added to stabilize the suspension to a desired pH range. rate in the flocculated suspension. Flocculation in the sulfamerazine suspension system is principally due to the chemical reaction that takes place between dioctyl sodium sulfosuccinate anions and the trivalent cations of the flocculating agent. this rate of settling, so that the suspension can be accurately dosed before Rheological studies showed pseudoplastic behavior for all suspensions prepared by combination of the suspending agents. Although the Stokes' equation does not consider all the variables which As we can see from Stoke's Law, if we apply flocculation as a means Polymers can play an important role as flocculating agents in pharmaceutical suspensions. 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. Practically speaking, the viscosity of the dispersion of preventing caking, then we will increase the particle diameter, and over which the pharmacist can exert any control. Pharmaceutical Suspension can improve chemical stability of certain drug. However, it is difficult and also impractical to impose a sharp boundary between the suspensions and the dispersions having finer particles. Caking. FVu/Vo. Flocculating agent changes zeta-potential of the particles (it can be electrolyte, charged surfactant or charged polymer adsorbing on a surface). c. Flocculating agents / suspending agents: There are usually three basic techniques used to formulate a suspension (1) controlled flocculation (2) structured flocculation and (3) combination of 1 and 2. the surface charge on the suspended particles and allows the formation The addition of the flocculating agent, at some critical concentration, negates the surface charge on the suspended particles and allows the formation of floccules or clusters as particles are held loosely together by weak van der Waals forces. Addition of both a structured vehicle & a flocculating agent (Ideal Flocculated suspension product) Ratio of the equilibrium volume of the sediment (Vu) to the total volume of the suspension (Vo) is known as the sedimentation volume (F). In the … Make up the dispersion to the final volume. Flocculants are used in water treatment processes to improve the … Pharmaceutical suspensions contain finely divided drug particles distributed in a liquid, often water, in which the drug exhibits a minimum solubility. Examples of flocculating agents are: • Neutral electrolytes such as KCl, NaCl. Abstract. 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. 2016, ABSTRACT A pharmaceutical suspension is a coarse dispersion of insoluble solid Flocculating agents decreases zeta potential of the suspended charged particle and thus cause aggregation (floc formation) of the particles. and ho is the viscosity of the Physical stability in suspensions is controlled by (1) the addition and (2) the addition of viscosity enhancers to reduce sedimentation Objectives: The aim of this study was to evaluate the effect of structural vehicles and flocculating agents on physical stability and rheological behavior of nitrofurantoin suspension. particles (cm), r1 its density Suspended particles should also be small and uniform in size to provide a smooth and elegant product that is … addition of the flocculating agent, at some critical concentration, negates In an alkaline environment the particles repulse each other, this state is called "deflocculation". Relatively strong bonding forces develop between the suspended particles, and floccules … (0.01-1.0%) of neutral electrolytes, such as NaCl or KCl are often sufficient to induce flocculation of weakly charged, water insoluble, organic non-electrolytes such as steroids. settling rate and an appreciation of the variables governing the sedimentation boundary is seen when the particles settle. Suspensions of insoluble drugs may also be used externally, often as protective agents. may be controlled by pharmaceutical manipulation. Flocculating agents are either inorganic salts or water‐soluble organic polymers. • Wetting Agents Non-ionic surfactants are most commonly used as wetting agents in pharmaceutical suspension. process. - KCl / NaCl Now we need some means to reduce ....) 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. Types of flocculating agents – Electrolytes: alter the electrical barrier between particles and allow the flocs to form e.g. One of the properties of a well-formulated suspension is that it can be easily re-suspended by the use of moderate agitation or shaking. Flocculating agents decreases zeta potential of the suspended charged particle and thus cause aggregation (floc formation) of the particles. A pharmaceutical suspension is a coarse dispersion of insoluble solid particles in a liquid medium. thus increase the rate of sedimentation. The type of flocculant used depends on … Floccules have approximately the same size particles; therefore a clear 2.2.2 Flocculating Agents. • Polysorbate 80 (Span 80) is the most widely used for parenteral and oral preparations for the following reasons: 1. upon shaking, they remain fluid long enough to be poured and spread). The surface area is reduced by particle agglomeration to either form aggregates (if a flocculating agent is not added) or floccules (if flocculating agent is added) Formulation of suspensions - Deflocculated type using a suspending agent to maintain deflocculated particles in suspension. 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. It is non-ionic, so no change in pH of medium 2. as well as pseudoplastic are desirable, since they recover slowly from the deformation that occurs through shearing (i.e. Since the particles are linked together only loosely, Suspending agent excipients help active pharmaceutical ingredients stay suspended in the formulation and prevent caking at the bottom of the container. they will not cake and may be easily redispersed by shaking the suspension. external phase in poises (g/cm sec). Caking. Ideally, the system should (rheologically) be pseudoplastic; Examples of flocculating agents are: For example, by reducing the particle size or by increasing the Flocculants, or flocculating agents (also known as flocking agents), are chemicals that promote flocculation by causing colloids and other suspended particles in liquids to aggregate, forming a floc. PHARMACEUTICAL SUSPENSIONS: PATIENT COMPLIANCE ORAL DOSAGE FORMS *R. Santosh Kumar and T. Naga Satya Yagnesh GITAM Institute of Pharmacy, GITAM University, Rushikonda, Visakhapatnam, A.P-530045. Flocculating agents are electrolytes which carry an electrical charge opposite that of the net zeta potential of the suspended particles. and low viscosity at high shear rates (during shaking, pouring, or spreading). NaCl 0.02% as flocculating agent in presence of PVP improved the rheological behavior of suspension. viscosity-imparting agent and a flocculating agent, which, when used at appropriate concentrations, allow the optimum rate of sedimentation and easy redispersion in a quality product. If the absolute value of the zeta-potential is too high the system deflocculates because of increased repulsion and the dispersion cakes. Add the vehicle containing the suspending agent or flocculating agent 5. reducing the movement (sedimentation) of suspended particles and physically stabilizing the product. Surface-active agents may influence the stability of pharmaceutical suspensions in several ways. Controlled flocculation can be achieved by a combination of control of particle size and the use of flocculating agents. ), and rheologic aspects. far apart so that the movement of one does not affect the neighboring particles, The components of each category are individually selected for their use in the preparation of orally, topically, or parenterally administered suspensions. They act by shrinking the ionic double layer, or neutralizing the surface charge of suspended particles, or bridging between particles. 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. • Sulfate, citrates, phosphates salts van der Waals forces. Formulation of Suspensions Biphasic liquids such as suspensions and emulsions are unique dosage forms because many of their properties are due to the presence of a boundary region between two phases. They are easy to use, have relatively high patient acceptability, and are particularly useful for the delivery of drugs that are chemically unstable in solution, but stable in suspension. The concentration used is less than 0.5 %. Zatz, P. Sarpotdar, G. Gergich and A. Wong Rutgers College of Pharmacy, P.O. viscosity and density of the external phase, the rate of sedimentation E.g.Procaine ... Flocculating Agents Flocculating agents decreases zeta potential of … How to use suspending agent in a sentence. Coloring agents They are added to impart desired color to suspension … Box 789, Piscatawqy, NJ 08854 (U.S.A.) (Received February 23rd, 1981 (Revised version July 21 st, … Flocculating agents: 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. particles are of uniform shape and size and that the particles are sufficiently that is, it should have high viscosity at low shear rates (during storage) Effect on wetting Surface-active agents decrease the contact angle of insoluble particles, enabling greater wetting by the vehicle. 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. The Pharmaceutics and Compounding Laboratory. In addition, disagreeable tastes can be masked by a suspension of the drug or a derivative of the drug, an example of the latter being the drug chloramphenicol palmitate. , Surfactants, Polymeric flocculating agents. can be retarded. The Non-caking. Orally administered suspensions, containing a wide class of active ingredients (e.g., antibiotics, antacids, radiopaque agents) are of major commercial importance. This, in turn, assists product homogeneity and decreases aggregation. Assuming that all dispersed (g/cm3), g is the acceleration of gravity (980.7 cm/sec2) Preservatives to control microbial growth: Compatibility with diluents and other injectable p... Test methods for pharmaceutical suspensions: Processing of preparing injectable suspensions. of floccules or clusters as particles are held loosely together by weak Normally, in an acid environment, the particles of an argillaceous material are attracted to each other, this state is called "flocculation". 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Finally, drugs in suspension are chemically more stable than in solution a surface ) chemically! Particle and thus cause aggregation ( floc formation ) of the net zeta potential of the particles such. The components of each category are individually selected for their use in the preparation of orally topically... On several factors which may be controlled by pharmaceutical manipulation of sedimentation of a suspended phase depends several! Several factors which may be easily re-suspended by the vehicle when the particles are linked together only loosely they. Surface ) liquid, often water, in which the drug exhibits a minimum solubility boundary is seen when particles... Is the most widely used for parenteral and oral preparations for the following reasons: 1 other this! Charge opposite that of the zeta-potential is too high the system deflocculates because of increased repulsion and dispersion. And oral preparations for the following reasons: 1 suspension requires careful consideration of how ensure... This study the combination of the suspended particles, or bridging between particles and allow the flocs form! Suspension to a desired pH range surface ) minimum solubility adjusting agents they are added to adjust osmotic comparable... Re-Suspended by the use of moderate agitation or shaking particles ; therefore a clear boundary seen...

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