Scale pharmaceuticals, extrusion

Substitute for Conventional Vulcanized Rubbers, For this application, the products are processed by techniques and equipment developed for conventional thermoplastics, ie, injection molding, extrusion, etc. The S—B—S and S—EB—S polymers are preferred (small amounts of S—EP—S are also used). To obtain a satisfactory balance of properties, they must be compounded with oils, fillers, or other polymers compounding reduces costs. Compounding ingredients and their effects on properties are given in Table 8. Oils with high aromatic content should be avoided because they plasticize the polystyrene domains. Polystyrene is often used as an ingredient in S—B—S-based compounds it makes the products harder and improves their processibility. In S—EB—S-based compounds, crystalline polyolefins such as polypropylene and polyethylene are preferred. Some work has been reported on blends of liquid polysiloxanes with S—EB—S block copolymers. The products are primarily intended for medical and pharmaceutical-type applications and hardnesses as low as 5 on the Shore A scale have been reported (53). 

Until recently, hot-melt extrusion had not received much attention in the pharmaceutical literature. Pellets comprising cellulose acetate phthalate were prepared using a rudimentary ram extruder in 1969 and studied for dissolution rates in relation to pellet geometry. More recently, production of matrices based on polyethylene and polycaprolactone were investigated using extruders of laboratory scale. Mank et al. reported in 1989 and 1990 on the extrusion of a number of thermoplastic polymers to produce sustained release pellets.A melt-extrusion process for manufacturing matrix drug delivery systems was reported by Sprockel and coworkers.As one can see, a review of the pharmaceutical scientific literature does not elucidate many applications for hot-melt extrusion in this field. 

When considering the scale-up of the extrusion process, it is instructive to first consider the scale of production which might be needed in the course of drug development, and the scale of equipment needed to reach that level of production. Because extrusion is an inherently continuous process, the level of production can be classified in terms of mass of extrudate produced per unit time, whereas the equipment used to achieve a given production rate is primarily classified by the outer diameter of the screw cross section. Table 7.2 lists typical production rates and equipment sizes for various product stages encountered in pharmaceutical development. 

The ability to construct pharmaceutical co-crystals on a large scale is important for the industrial application of mechanosynthesis. This aspect of mechanochemical co-crystallisation was recently addressed by Medina et al. who described a scalable solvent-free process for pharmaceutical co-crystallisation by using twin screw extrusion. ... 

Styrene-acrylonitrQe (SAN) copolymer is a brittle material but has improved surface hardness and chemical resistance when compared with polystyrene and has excellent resistance to weathering. It is available in granules from transparent pale straw colour through a full range to opaque colours. SAN is processable by injection or blow moulding and extrusion. Applications include table, picnic and kitchen ware where resistance to fruit juices and natural oils is important, cosmetic and pharmaceutical packaging for similar reasons, refrigerator parts, and radio controls and scales. 

Equally, there are one or two types of replaceable element filter that do not fit the precise definition of a cartridge filter given above, yet are included here because of their similarity of function. These are the capsule filters, much used in laboratories and small-scale production processes such as are involved in the pharmaceutical and life science sectors, and the polymer melt filters, employed to ensure the freedom from blockage of extrusion nozzles for polymer fibres and filaments. 

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