PHARMACEUTICAL PELLETS :APPLICATIONS AND INNOVATIVE APPROC

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Pharmaceutical pellets :Industrial appilications &innovative perspective :

Pharmaceutical pellets :Industrial appilications &innovative perspective

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ADVANTAGES : 1.Improved aesthetic appearance of products. 2.Coating of drug pellets with different polymers to achieve controlled release rate of drugs. For immediate release products larger surface area of pellets enables better distribution, dissolution and absorption 18 . 3.Chemically incompatible products can be formulated into pellets and delivered in a single dosage form by encapsulating them 19,20 . 4.Pellets ensure improved flow properties and flexibility in formulation development and manufacture.

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5. The coating material may be colored with adye material so that the beads of different coating thickness will be darker in color and distinguishable from those having fewer coats and the beads or granules of different thickness of coatings are blended together in the desired proportions to give the desired effect. 6. The thickness of the coat over the drug pellets ensures the rate at which the drug/contents are released from the coated particles. A smooth surface of the pellet provides uniform 4.

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DEFINITION: Small free flowing sperical units ranging in size , prepared by an agglomeration of fine powders are called as pellets. Why pellets? . Pellets have varied applications in a number of industries and an innovative use of its could achieve maximum profitability. Some of the few instances where smooth surfaced uniform pellets are being successfully used .

INTRODUCTION:

INTRODUCTION Pellets ensure improved flow properities and flexibility in formulation development and manufacture . in the pellet surface is smoother it allows thin or thick coat of the polymer on the surface the pellets . The thick of the coat determineds the rate at which the drug released from the coated pellets .

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It is widely used for frequently administered drugs having a half life of 0.5 to 2hrs . In the very high drug substance load level of the micro pellets promotes lower injection volumes thus increasing g patients acceptence ,examples narcoleptics, peptides hormones. The release rate of drugs from the polymer coat from the coat can be modified using various concentration of plasticizer and influence of PH.

FORMULATION OF PELLETS: :

FORMULATION OF PELLETS: Excipients may vary widely in their chemical composition and physical properties and are classified mainly in terms of their functional role during the development and manufacture of dosage forms. The physicochemical properties of both excipients and drugs are crucial to the successful development of pelletized products and should be thoroughly examined. Therefore, conventional preformulation screening-involving compatibility and stability of the drug in combination with a variety of excipients-should be performed in the same manner as is done in any solid-dosage form development sequence .

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Binders / agglomeration inducers / bridging agents: Binders are adhesive materials that are incorporated in pellet formulations to bind powders and maintain pellet integrity and it may be added as a solution than the dry form, although application via solution is more efficient than dry mixing followed by liquid addition. When applied as solution form, binders are dissolved/dispersed in organic or aqueous solvent, however the latter is most preferred and commonly used system in pelletization.

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The binders are commonly used in the range of 2-10%w/w or v/v and should be optimized so that the pellets are durable and not friable and yet to maintain the other desirable properties of the pellets, such as releasing the drug at the intended rate . Examples: 1

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SEPARATING AGENTS : Separating agents are materials that adsorb on the surface and promote the separation of pellets into distinct units during a pelletization process 27 which are incorporated initially in the formulation or externally during processing to avoid some problems such as pellets may tend to attract one another due to surface charge development during the process, binding the pellets together leads to the formation of aggregates due to subsequent addition of binding agents, and agglomeration of pellets due to the wetness of the surface of the pellets coupled with the local concentration of the binding agents. The amount of separating agent required varies with the type of formulation and the manufacturing process

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pH adjusters The pH adjusters are substances that are incorporated in pellet formulations to influence the microenvironment of drug molecules for a variety of reasons. Generally acid-labile compounds are protected from the acidic region of the GIT by the application of an enteric coating. Buffer systems may also be added to the core formulation to maintain the pH to the core in a favorable range for drug stability.

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Lubricants In pelletization process, lubricants are rarely used especially where high-speed rotary equipments are utilized. However, during compression and Extrusion- Spheronization , lubricants may play a crucial role in the successful manufacture of pellets. They are used to reduce the friction between the die wall and powder mix during the compression and ejection phase.

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Release modifiers The main thrust of pelletization process is to manufacture spherical drug cores that will be subsequently coated in a separate step with some sort of a functional membrane or it is also possible to prepare pellet cores that inherently possess specific release profiles in a single step which can be achieved by the incorporation of release modifiers along with drug during the core formulation. . Generally, water soluble low molecular weight substances, surfactants and disintegrants may be incorporated in formulations to enhance the release rate of drugs, while water insoluble polymers, hydrophobic substances, inorganic salts, and hydrophilic polymers that swell and/or form gels are incorporated in pellets to retard release rates 31 .

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EXAMPLE 1 : Duloxetine base/capsule Beads Microcrystalline cellulose , Finishing layer Duloxetine la yer Duloxetine White beeswax Hydrated silicon dioxide β-lactose Cross-linked polyvinylpyrrolidone (crospovidone) Hydroxypropylcellulose Talc Separating layer Hydroxypropylmethylcellulose Polyethylene glycol 6000 Talc Titanium dioxide Enteric layer Triethyl citrate TalLC

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PROCESS: 1.The pellet batch is prepared in a fluid-bed coating device ( Aeromatic - Fielder MP-4/5) by bottom spray and with three Wurster columns installed . 2.Drug layer is applied onto inert sugar beads of a particle size 600-710 microns. The coating fluid is prepared by combining a dispersion of Duloxetine hydrochloride in water and a dispersion of methyl cellulose in water. 3.Separating layer is applied onto the so coated beads. The coating fluid is prepared by combining a dispersion of hypromellose in water with a dispersion of sucrose and talc in water (prepared by dissolution of sucrose in water followed by dispergating talc under mechanical stirring). The hypromellose is allowed to hydrate in water for at least one night. .

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4.Enteric coating layer is applied onto the beads with the above two coatings. The coating fluid is prepared by dissolving Eudragit in an isopropanol-water mixture (ratio 19:1), followed by addition of dibutylsebacate and dispergating of talc in the fluid. 5.After the coating, the pellets are cured overnight in a ventilated oven at 50° C

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