the rate of sedimentation can be estimated by Stoke's equation: where V is the sedimentation rate (cm/sec), d the diameter of the suspended The most common categories of flocculating ⦠Buffers and pH adjusting agents They are added to stabilize the suspension to a desired pH range. Flocculating agents are electrolytes which carry an electrical charge 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. of flocculating agents to enhance particle "dispersability" Background: Nitrofurantoin is a nitrofuran antibiotic that has been used for treatment of urinary tract against positive and negative bacteria. 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. Examples of flocculating agents are: Suspending agents which are thixotropic and (2) the addition of viscosity enhancers to reduce sedimentation 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. A pharmaceutical suspension is a coarse dispersion of insoluble solid particles in a liquid medium. viscosity and density of the external phase, the rate of sedimentation 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. Zatz, P. Sarpotdar, G. Gergich and A. Wong Rutgers College of Pharmacy, P.O. E.g.Procaine ... Flocculating Agents Flocculating agents decreases zeta potential of ⦠In this study the combination of the suspending agents showed better results in comparison with other formulations. over which the pharmacist can exert any control. This is particularly important in flocculated 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. ....) 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. Floccules have approximately the same size particles; therefore a clear Article Received on 19 October. The concentration used is less than 0.5 %. Surface-active agents may influence the stability of pharmaceutical suspensions in several ways. process. 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 rate of sedimentation of a suspended phase depends on several factors which 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 systems in which rapid particle settling is the primary factor leading external phase in poises (g/cm sec). Ideally, the system should (rheologically) be pseudoplastic; - KCl / NaCl Packaging and storage of suspensions: All suspensions should be packaged in wide mouth container having adequate airspace above the liquid ⦠of preventing caking, then we will increase the particle diameter, and affect the stability of a suspension, it gives an approximation of the Suspending agent excipients help active pharmaceutical ingredients stay suspended in the formulation and prevent caking at the bottom of the container. 2016, ABSTRACT A pharmaceutical suspension is a coarse dispersion of insoluble solid This leads to a greater flexibility in the use of additives such as preservatives, flavoring and coloring agents that might be needed van der Waals forces. In case of more highly charged, insoluble polymers and polyelectrolyte species, such as Ca-salts and alums or sulphates, citrates and phosphates are usually required to achieve floc formation depending on particle charge, positive or negative. This, in turn, assists product homogeneity and decreases aggregation. Caking. , Surfactants, Polymeric flocculating agents. ⢠Sulfate, citrates, phosphates salts NaCl 0.02% as flocculating agent in presence of PVP improved the rheological behavior of suspension. Relatively strong bonding forces develop between the suspended particles, and floccules ⦠addition of the flocculating agent, at some critical concentration, negates They act by shrinking the ionic double layer, or neutralizing the surface charge of suspended particles, or bridging between particles. Small conc. Controlled flocculation can be achieved by a combination of control of particle size and the use of flocculating agents. and low viscosity at high shear rates (during shaking, pouring, or spreading). Normally, in an acid environment, the particles of an argillaceous material are attracted to each other, this state is called "flocculation". 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. Flocculating agents They are added to floc the drug particles Thickeners They are added to increase the viscosity of suspension. as well as pseudoplastic are desirable, since they recover slowly from the deformation that occurs through shearing (i.e. Pharmaceutical suspensions contain finely divided drug particles distributed in a liquid, often water, in which the drug exhibits a minimum solubility. Practically speaking, the viscosity of the dispersion Effect on wetting Surface-active agents decrease the contact angle of insoluble particles, enabling greater wetting by the vehicle. Polymers can play an important role as flocculating agents in pharmaceutical suspensions. and r2 is the density of the medium 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. medium is the only other Stoke's variable affecting sedimentation rate 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. Rheological studies showed pseudoplastic behavior for all suspensions prepared by combination of the suspending agents. agents are added to suspensions to thicken the suspending medium, thereby reducing the movement (sedimentation) of suspended particles and physically Physical stability in suspensions is controlled by (1) the addition How to use suspending agent in a sentence. 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. The type of flocculant used depends on ⦠boundary is seen when the particles settle. Flocculating agents decreases zeta potential of the suspended charged particle and thus cause aggregation (floc formation) of the particles. that is, it should have high viscosity at low shear rates (during storage) Now we need some means to reduce 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. it begins to settle. Orally administered suspensions, containing a wide class of active ingredients (e.g., antibiotics, antacids, radiopaque agents) are of major commercial importance. settling rate and an appreciation of the variables governing the sedimentation 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. Suspended particles should also be small and uniform in size to provide a smooth and elegant product that is ⦠Abstract. ⢠Polysorbate 80 (Span 80) is the most widely used for parenteral and oral preparations for the following reasons: 1. the surface charge on the suspended particles and allows the formation However, it is difficult and also impractical to impose a sharp boundary between the suspensions and the dispersions having finer particles. to physical instability and lack of dosage uniformity in the product. Flocculating agents are electrolytes which carry an electrical charge opposite that of the net zeta potential of the suspended particles. 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. 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 Suspension can improve chemical stability of certain drug. Since the particles are linked together only loosely, It is non-ionic, so no change in pH of medium 2. and ho is the viscosity of the Finally, drugs in suspension are chemically more stable than in solution. rate in the flocculated suspension. As we can see from Stoke's Law, if we apply flocculation as a means far apart so that the movement of one does not affect the neighboring particles, Make up the dispersion to the final volume. Although the Stokes' equation does not consider all the variables which Flocculating Agents flocculating agents decreases zeta potential of the suspended charged particle and thus cause aggregation (flock formation) of the particles. Settling or sedimentation is pro⦠If the absolute value of the zeta-potential is too high the system deflocculates because of increased repulsion and the dispersion cakes. may be controlled by pharmaceutical manipulation. In the ⦠thus increase the rate of sedimentation. Flocculants are used in water treatment processes to improve the ⦠FVu/Vo. (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. Non-caking. this rate of settling, so that the suspension can be accurately dosed before Flocculating agent changes zeta-potential of the particles (it can be electrolyte, charged surfactant or charged polymer adsorbing on a surface). Types of flocculating agents â Electrolytes: alter the electrical barrier between particles and allow the flocs to form e.g. Suspending or thickening 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. Box 789, Piscatawqy, NJ 08854 (U.S.A.) (Received February 23rd, 1981 (Revised version July 21 st, ⦠Suspensions of insoluble drugs may also be used externally, often as protective agents. Add the vehicle containing the suspending agent or flocculating agent 5. As such, polymers can have an advantage over ionic flocculating agents in that they are less sensitive to added electrolytes. Coloring agents They are added to impart desired color to suspension ⦠These are briefly summarized below. they will not cake and may be easily redispersed by shaking the suspension. poured and spread). particles are of uniform shape and size and that the particles are sufficiently In suspensions, a liquid and an insoluble solid meet to form an interface. 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. stabilizing the product. Examples of flocculating agents are: ⢠Neutral electrolytes such as KCl, NaCl. (g/cm3), g is the acceleration of gravity (980.7 cm/sec2) ), and rheologic aspects. 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. 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). Osmotic agents They are added to adjust osmotic pressure comparable to biological fluid. 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. Flocculating agents are either inorganic salts or waterâsoluble organic polymers. can be retarded. In an alkaline environment the particles repulse each other, this state is called "deflocculation". ⢠Wetting Agents Non-ionic surfactants are most commonly used as wetting agents in pharmaceutical suspension. For example, by reducing the particle size or by increasing the The formulation of a pharmaceutical suspension requires careful consideration of how to ensure homogeneous drug distribution during administration. Preservatives to control microbial growth: Compatibility with diluents and other injectable p... Test methods for pharmaceutical suspensions: Processing of preparing injectable suspensions. The Pharmaceutics and Compounding Laboratory. upon shaking, they remain fluid long enough to be 2.2.2 Flocculating Agents. Assuming that all dispersed particles (cm), r1 its density Flocculating agents decreases zeta potential of the suspended charged particle and thus cause aggregation (floc formation) of the particles. of floccules or clusters as particles are held loosely together by weak 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. Examples of flocculating agents used in pharmaceutical suspension (usually at concentrations 0.01 â 1.00 %) include sodium or potassium chloride, aluminum chloride, calcium salts, ⦠The components of each category are individually selected for their use in the preparation of orally, topically, or parenterally administered suspensions. High Efficiency Flocculating Agents In Pharmaceutical Suspensions Dadmac 7398-69-8. 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