The design of equipment for use in controlled environment areas follows similar principles, whether for general injectable manufacturing or for the manufacturer of sterile ophthalmic pharmaceuticals. All tanks, valves, pumps, and piping must be of the best available grade of corrosion-resistant stainless steel. In general, stainless steel type 304 or 316 is preferable. All product-contact surfaces should be finished either mechanically or by electropolishing to provide a surface as free as possible from scratches or defects that could serve as a nidus for the commencement of corrosion (338). Care should be taken in the design of such equipment to provide adequate means of cleaning and sanitization. For equipment that will reside in aseptic-filling areas, such as filling and capping machines, care should be taken in their design to yield equipment as free as possible from particle-generating mechanisms. Wherever possible, belt or chain-drive concepts should be avoided in favor of sealed gear or hydraulic mechanisms. Additionally, equipment bulk located directly over open containers should be held to an absolute minimum during filling and capping operations to minimize introduction of equipment-generated particulate matter or creation of air turbulence. This precaution is particularly important when laminar flow is used to control the immediate environment around the filling-capping operation.
In the design of equipment for the manufacture of sterile ophthalmic (and nonophthalmic) pharmaceuticals, manufacturers and equipment suppliers are turning to the advanced technology in use in the dairy and aerospace industries, where such concepts as clean in place (CIP), clean out of place (COP), automatic heliarc welding, and electropolishing have been in use for several years. As a guide here, the reader is referred to the so-called 3A Standards of the dairy industry issued by the U.S. Public Health Service (339).
Some of the newer and more potent drugs, like the prostaglandins, which are produced at very low concentrations in the finished formulation, may require special precautions during compounding and processing to prevent loss of actives due to adsorption/absorption to the walls of fill lines and/or storage tanks.
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