Pellets, preparation extrusion

Lovgren K, Lundberg PJ. Determination of sphericity of pellets prepared by extrusion-spheronization and the impact of some process parameters. Drug Dev Ind Pharm 1989 15 2375-2392. 

Fig. 22 Pellets prepared by different methods. Cross-sectional view of a pellet prepared by powder layering (A), cross-sectional view of a pellet prepared by extrusion/spher-onization (B), and size and shape of pellets prepared by extrusion/spheronization (C).

Pellets prepared by extrusion/spheronization have uniform cross-sectional area (Fig. 22B) but differ slightly in shape and size, which is based on the spheronization process following extrusion (Fig. 22C). 

An immediate release product would require some special feature to warrant the increased cost of production when compared to a conventional capsule or tablet. Therefore, the major commercial use of pellets prepared by extrusion/spheronization is in the preparation of controlled release products and there are several highly successful products available. In particular the ability to produce pellets with a high drug loading offers advantages over alternative methods of forming pellets. 

Tomer G, Podczeck F, Newton JM. The influence of model drugs on the preparation of pellets by extrusion/spheronization 11 sphcronization parameters. Int J Pharm 2002 231 107-19. 

Perez JP, Rabiskova M. Influence of the drying technique on theophylline pellets prepared by extrusion-spheronization. Int J Riarm 2002 242 349-51. 

Sriamomsak P, Nunthanid J, Luangtana-anan M, et al. Alginate-based pellets prepared by extrusion/spheronization A preliminary study on the effect of additive in granulating liquid. Eur J Pharm Biopharm 2007 67 227-35. 

Blanque D. Stemagel H, Podczeck F el al. Some factors Influencing the formation and in vitro drug release from matrix pellets prepared by extrusion/spheronizatton. Int J Pharm 1995 119 203-11. 

Souto C, Rodriguez A, Parajes S, et al. A comparative study of the utility of two super-disintegrants in microcrystalline cellulose pellets prepared by extrusion/spheronization. Eur J Pharm Biopharm 2005 61 94-9. 

To render materials suitable for pelleting or extrusion, they must have inherent binding characteristics or contain binders and feature a certain lubricity. Therefore, most medium pressure agglomeration techniques use moist mixtures which are prepared in a mixing step prior to pelleting. 

One of the simplest, most commonly used techniques for preparing a catalyst involves dispersing an active component (or components) on a support material. Normally, one impregnates the carrier material with a solution of a soluble precursor of the catalyst and then converts this precursor to the product desired by oxidation, reduction, thermal decomposition, or some other suitable step. Where appropriate, it is preferable to use a granular support instead of a powder, because it eliminates the necessity for pelleting or extrusion to obtain the final product. 

Schilling, S.U. Lirola, H.L. Shah, N.H. Waseem Malick, A. McGinity, J.W. Influence of plasticizer type and level on the properties of Eudragit SlOO matrix pellets prepared by hot-melt extrusion. J. Microencap. 2010, 27(6), 521-532. 

Powder compact n. A molding material in the form of dry, friable pellets prepared by compacting dry-blended mixtures of resin (typically PVC) with plasticizers and other compounding ingredients. The powder compacts are about as easy to handle and process by extrusion as pellets and offer the advantages of lower heat history and somewhat lower cost than equivalent materials in the form of fused pellets. 

Varshosaz J, Kennedy RA, Gipps EM. Effect of binder level and granulating liquid on phenylbutazone pellets prepared by extrusion-spheronization. Drug Dev Ind Pharm 1997 23(6) 611-618. 

Dyer AM, Khan KA, Aulton ME. Effect of the dr5dng method on the mechanical and drug release properties of pellets prepared by extrusion. Drug Dev Ind Pharm 1994 20 3045-3068. 

A reported application of canonical analysis involved a novel combination of the canonical form of the regression equation with a computer-aided grid search technique to optimize controlled drug release from a pellet system prepared by extrusion and spheronization [28,29]. Formulation factors were used as independent variables, and in vitro dissolution was the main response, or dependent variable. Both a minimum and a maximum drug release rate was predicted and verified by preparation and testing of the predicted formulations. Excellent agreement between the predicted values and the actual values was evident for the four-component pellet system in this study. 

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