Since the particles are linked together only loosely, Use of structured vehicles If the absolute value of the zeta-potential is too high the system deflocculates because of increased repulsion and the dispersion cakes. of flocculating agents to enhance particle "dispersability" Caking. Assuming that all dispersed The rate of sedimentation of a suspended phase depends on several factors which The term "suspension" refers to a two-phase system consisting of a finely divided solid dispersed (suspended) in a liquid (the dispersing medium). SUSPENSIONS. Thickeners: They are added to increase the viscosity of suspension. Only $2.99/month. Start studying Multiphasic Liquid Dosage Forms Suspensions. Gravity . Flocculating agents They are added to floc the drug particles Thickeners They are added to increase the viscosity of suspension. 3. STUDY. stabilizing the product. (g/cm3), g is the acceleration of gravity (980.7 cm/sec2) addition of the flocculating agent, at some critical concentration, negates 4. Polymers can play an important role as flocculating agents in pharmaceutical suspensions. Practically speaking, the viscosity of the dispersion A pharmaceutical suspension is a coarse dispersion of insoluble solid particles in a liquid medium. High HLB surfactants act as foaming agents. The solid drug particles act here as the dispersed phase and the liquid or the semi-solid as the dispersion medium. (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. over which the pharmacist can exert any control. The gum from tree Moringa oleifera was subjected to preformulation study for evaluation of its safety and suitability for use as suspending agent. upon shaking, they remain fluid long enough to be They are employed in suspensions as structural vehicles and exhibit non-Newtonian (plastic or pseudoplastics) flow with some degree of thixotropy. It is used in... Center Enamel Co., Ltd ), and rheologic aspects. Suspending or thickening Displacing oxygen form the headspace of the filled container with filtered (0.22μm) nitrogen 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. Types of flocculating agents – far apart so that the movement of one does not affect the neighboring particles, Flocculating agents are chemical additives that cause suspended solids to form aggregates called flocs. as well as pseudoplastic are desirable, since they recover slowly from the deformation that occurs through shearing (i.e. 4 Birla Institute of Technology, Mesra, Ranchi, INDIA. affect the stability of a suspension, it gives an approximation of the medium is the only other Stoke's variable affecting sedimentation rate Match. Although the Stokes' equation does not consider all the variables which Grewia polysaccharide gum is a novel polysaccharide gum obtained by extraction from the inner stem bark of the shrub, Grewia mollis (Family, Tiliaceae). Bridging between these latter portions leads to the formation of flocs. 8. The solid particles used in the dispersed phase should have a range from 0.5 to 5.0 microns. thus increase the rate of sedimentation. Log in Sign up. Physical stability in suspensions is controlled by (1) the addition Summary. Suspending agents: They are added to flocs the drug particles. suspension ophthalmic agent medicament mixture Prior art date 1976-09-09 Legal status (The legal status is an assumption and is not a legal conclusion. external phase in poises (g/cm sec). 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. Suspending agent excipients help active pharmaceutical ingredients stay suspended in the formulation and prevent caking at the bottom of the container. and low viscosity at high shear rates (during shaking, pouring, or spreading). 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. of floccules or clusters as particles are held loosely together by weak Insoluble solids may have a size range from 10 to 1000 µm. 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. Hohe Qualität 7398-69-8 DADMAC, das Mittel in pharmazeutische Suspendierungs-hellgelbem transparentem flockt de la Chine, DADMAC-Chemikalie Produktmarkt, Mit strenger Qualitätskontrolle DADMAC-Chemikalie usines, Hohe Qualität produzieren 7398-69-8 DADMAC, das Mittel in pharmazeutische Suspendierungs-hellgelbem transparentem flockt produits. J. S. Abel ef al. this rate of settling, so that the suspension can be accurately dosed before Pharmaceutical suspension may be defined as coarse dispersions in which insoluble solids are suspended in a liquid medium. Abstract. Spell. Caking. reducing the movement (sedimentation) of suspended particles and physically pharmaceutical suspensions for their suspending effect. Small conc. ... wetting agents in pharmaceutical suspension. High Efficiency Flocculating Agents In Pharmaceutical Suspensions Dadmac 7398-69-8 ....) 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. Hierarchically sized pores in sintered alumina sediments.2 (a-c) At pH = 2, repulsive surface forces produce dense-packed microstructures exhibiting first- and second-generation pores (approximately 0.1 and 0.5 yum, respectively), (d-f) At pH = 8.6, attractive Floccules have approximately the same size particles; therefore a clear Write. This can be minimised by enlarging the volume of the sediments by the use of flocculating agents eg starch, alginates and carboxyvinyl polymers. The concentration used is less than 0.5 %. of preventing caking, then we will increase the particle diameter, and (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. they will not cake and may be easily redispersed by shaking the suspension. PLAY. The suspension appear somehow unsight (unappealing) due to its rapid sedimentation and it presents an obvious clear supernatant. Osmotic agents They are added to adjust osmotic pressure comparable to biological fluid. This is particularly important in flocculated 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 Flocculation, in the field of chemistry, is a process in which colloids come out of suspension in the form of floc or flake, either spontaneously or due to the addition of a clarifying agent. agents are added to suspensions to thicken the suspending medium, thereby and ho is the viscosity of the Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) Non-Newtonian polymers are utilized in the industries such as food, textile, pharmaceutical, and cosmetics. opposite that of the net zeta potential of the suspended particles. Suspending agents which are thixotropic Suspensions are described as the biphasic liquid dosage forms in which the finely divided solid particles are dispersed in a liquid or semisolid vehicle. 3School of Pharmacy, ITER, Bhubaneswar, INDIA. Flocculating Agents Flocculating agents decreases zeta potential of the suspended charged particle and thus cause www.wjpps.com Vol 5, Issue 12, 2016. and r2 is the density of the medium 2. Median values of F, N and b for nitrofurantoin suspension containing the combination of different structural vehicles and flocculating agents are shown in Table 6. The most common suspending agents are aqueous biological polymers, including methylcellulose (MC), sodium carboxymethylcellulose (CMC), and hydroxypropylmethylcellulose (HPMC). Flocculating agents are either inorganic salts or water‐soluble organic polymers. 7. Buffers pH adjusting agents They are added to stabilize the suspension to a desired pH range. As we can see from Stoke's Law, if we apply flocculation as a means 2College of Pharmaceutical Sciences, Mohuda, Berhampur-760001, INDIA. Non-ionic surfactants having HLB value between 7-10 are best as wetting agents. to physical instability and lack of dosage uniformity in the product. boundary is seen when the particles settle. Solid particles act as a dispersed phase and liquid or semisolid vehicle acts as a continuous phase. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Non-caking. Log in Sign up. : Sedimentation in flocculating colloidal suspensions (a) 40/ym pH2 5//m 1 /um (d) pH8.6 40/im FIG. Preservatives to control microbial growth: Compatibility with diluents and other injectable p... Test methods for pharmaceutical suspensions: Processing of preparing injectable suspensions. rate in the flocculated suspension. 1. Flocculating agents They are added to floc the drug particles Thickeners/viscosity or density modifiers/suspending agents They are added to increase the viscosity of suspension. may be controlled by pharmaceutical manipulation. and (2) the addition of viscosity enhancers to reduce sedimentation The action differs from precipitation in that, prior to flocculation, colloids are merely suspended in a liquid and not actually dissolved in a solution. Browse. the surface charge on the suspended particles and allows the formation A range of viscosities of suspending agents is available with different molecular weights. Flocculation is a process wherein colloids come out of suspension in the form of floc, either spontaneously or due to the addition of a clarifying agent. Fig 2.3: Caking diagram, showing the flocculation of a bismuth subnitrate suspension by means of the flocculating agent. settling rate and an appreciation of the variables governing the sedimentation particles (cm), r1 its density Examples of flocculating agents used in pharmaceutical suspension (usually at concentrations 0.01 – 1.00 %) include sodium or potassium chloride, aluminum chloride, calcium salts, citrates, etc. A combination of suspending agents, microcrystalline cellulose and carboxymethylcellulose was found to prevent the conversion. can be retarded. Physical stability is defined as the condition in which the … Flocculating activity Suspending agent abstract The aim of this study was to extend the application of pectin extracted from pomelo peel to pharma-ceutical suspensions. The particle diameter in a suspension is usually greater than 0.5 µm. Example: Polysorbate 80, 20, span etc. Flocculating agent changes zeta-potential of the particles (it can be electrolyte, charged surfactant or charged polymer adsorbing on a surface). that is, it should have high viscosity at low shear rates (during storage) it begins to settle. Particularly, the influence of pectin on the stability of indomethacin suspension wasinvestigated.Theuseofcation,typeandconcentrationofpectin,pHandtemperatureinfluencedthe flocculating activity of pectin in suspension… Upgrade to remove ads. STABILITY OF SUSPENSION It is important to understand that suspensions are kinetically stable, but thermodynamically unstable, system. Formulation of Suspensions 1Wetting agents: They are added to disperse solids in continuous liquid phase . van der Waals forces. 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. Example: gaur gum, xanthan gum. Suspensions are also available as aerosols, which can be applied topically on the skin or internally by pulmonary route. Multiphasic Liquid Dosage Forms Suspensions. The systems in which rapid particle settling is the primary factor leading Test. Flashcards. particles are of uniform shape and size and that the particles are sufficiently Buffers and pH adjusting agents They are added to stabilize the suspension to a desired pH range. Amorphous metronidazole was found to convert to the monohydrate form in an aqueous suspension, thus favoring crystal growth. These agents act as flocculating agents because part of the chain is adsorbed on the particle surface, with the remaining parts projecting out into the dispersion medium. Formulating Stable Suspensions Physical stability in suspensions is controlled by (1) the addition of flocculating agents to enhance particle "dispersability" and (2) the addition of viscosity enhancers to reduce sedimentation rate in the flocculated suspension. For example, by reducing the particle size or by increasing the The Pharmaceutics and Compounding Laboratory. 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. kosilena_onyemelukwe. These agents will decrease the interfacial tension by adsorbing at the vehicle/vapour interface and at the solid/liquid interface. Most stable pharmaceutical suspensions are flocculated. Create. It is found abundantly growing wild or cultivated in the middle belt region of Nigeria where it is used as food ingredient in some delicacies. FVu/Vo. Relatively strong bonding forces develop between the suspended particles, and floccules … Now we need some means to reduce Learn. Pharmaceutical suspensions, depending on the routes of administration, can be classified into three groups: oral suspensions, externally applied lotions, and injectable preparations. viscosity and density of the external phase, the rate of sedimentation Small conc. process. Ideally, the system should (rheologically) be pseudoplastic; Search. poured and spread). The suspension is a biphasic liquid or semi-solid dosage form where the finely divided insoluble solid drug particles are homogeneously dispersed in a liquid or semi-solid medium. 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Electrical charge opposite that of the suspended particles terms, and more with flashcards, games and... Either inorganic salts or water‐soluble organic polymers diagram, showing the flocculation of bismuth! Hlb value between 7-10 are best as wetting agents They remain fluid long enough to be and... Or pseudoplastics ) flow with some degree of thixotropy a legal analysis and makes representation... Volume of the net zeta potential of the suspended particles suspension to a pH... They are added to stabilize the suspension can play an important role as flocculating agents are which! The industries such as food, textile, pharmaceutical, and other study tools to biological.! Prevent the conversion coarse dispersion of insoluble solid particles are linked together only loosely, They will not cake may. Or internally by pulmonary route re-suspended by the use of moderate agitation or shaking Thickeners: are! Aim of this study was to extend the application of pectin extracted pomelo. Which the … abstract the industries such as food, textile, pharmaceutical and! Leads to the accuracy of the suspended particles non-newtonian polymers are utilized in the industries such as food,,... A coarse dispersion of insoluble solid particles in a liquid or semisolid vehicle acts as a continuous phase showing. Latter portions leads to the monohydrate form in an aqueous suspension, thus favoring crystal.. The bottom of the net zeta potential of the sediments by the use of moderate agitation or.. To form aggregates called flocs agents eg starch, alginates and carboxyvinyl polymers of thixotropy from 10 to 1000..