Issue link: https://www.e-digitaleditions.com/i/807837
ground because of its cost: A common fluid-bed proces- sor is roughly five times the price of a conventional mixer. In addition, because of the large amounts of air that fluid-bed processes use and their need for air condi- tioning equipment, they cost much more to operate than other coating equipment. Plowshare mixers [2] offer a lower-priced and reliable alternative, so long as the drying step of the process is managed to prevent abrasion from damaging the coating. Unlike fluid-bed processors, plowshare mixers fluidize powders and granules mechanically. As a result, using mixers as coaters requires precise control of the process parameters, including agitator speed, batch size, tempera- ture, and rate of nitrogen addition. Mechanical coaters also offer more flexibility than fluid-bed systems. Capitalizing on that flexibility, how- ever, requires that you decide at an early stage which processes the mixer will perform and then design the machine for that purpose. Possibilities include powder blending, granulation, and drying. Ideally, the machine would perform more than one process, thereby minimiz- ing handling and the need for containment. Drum coaters While fluid-bed processors and horizontal mixers are the best choices for coating small particles, drum coaters are better for large particles, including tablets. (They are also used in some food applications.) Drum coaters adapt easily to meet the needs of special applications and sophisticated products. For instance, it's possible to mod- ify these coaters to provide high containment. In fact, the entire process can be contained, which is the best way to protect people, products, and the environment. The coaters can also be made explosion-proof and can include built-in cleaning systems. In recent years, pharmaceutical manufacturers have been seeking more efficient coaters, as well as systems that are more user-friendly, easier to clean, and easier to manage. Realizing those objectives requires that each sub-process—spraying, mixing, and drying—be well thought out. My company's LC series of coaters, for example, operate as much as 40 percent faster than con- ventional drum coaters. This is due to the drum's geome- try, specifically the diameter and length of the perforated area, which provides a large surface over which to spray. As a result, it's possible to use more spray guns than in conventional drums, which allows the coater to apply more of the coating suspension to the tablets per unit of time. The drum's design also boosts process volume and shortens drying time, thereby reducing overall coating time. Because processing is faster—and product quality consistent—manufacturers can specify smaller coating machines and decrease capital expense. While most drum coaters apply polymer-based film coatings, interest in applying sugar coatings has increased. Ideally, the same equipment would apply both coating types without requiring major conversions. If you think sugar coating may be required, raise the issue with the equipment supplier you're considering. Reputable suppliers should be able to offer you a single unit with enough flexibility to apply both. T&C References 1. LFP fluid-bed processor from Lödige. 2. Ploughshare is a registered trademark of Lödige. Reiner Lamperle is sales manager at Gebr. Lödige Maschinen- bau, Paderborn, Germany. The company is represented in the USA, Puerto Rico, and Canada by Modwave, 1020 Mon- terey Boulevard, Suite 2, Hermosa Beach, CA 90254. Tel. 310 918 6772. Website: www.modwave.com. 30 April 2017 Tablets & Capsules Ploughshare [2] mixer LC70 drum coater