Issue link: https://www.e-digitaleditions.com/i/1371139
12 May/June 2021 Tablets & Capsules succession. A typical setup for the Bohle Koco coater operating in the rapid-turnaround mode is shown in Figure 4. In this example, the processing time per sublot was 40 minutes, with an overall process throughput rate of >50 kg/h. Interestingly, the coating weight uniformity achieved equated to a relative standard deviation (RSD) of 7 percent, which is much better than a typical coater operating in batch mode. This example used a standard HPMC/poly- ethylene glycol (PEG) coating formulation. A high-solids coating formulation could potentially cut the coating time in half, consequently doubling the throughput rate. Another interesting approach to semi-continuous rapid- turnaround batch coating is the GEA Omega coater, which Rapid-turnaround batch coaters Growing interest in fully continuous manufacturing pro- cesses raised an important question as to how to introduce film coating into this concept. As discussed earlier, some approaches have involved downsizing fully continuous coating processes or using semi-continuous coating pro- cesses. Early on, however, thought was given to adapting batch-processing concepts to a rapid- turnaround process. One approach presented by Bohle was to adapt the Koco coating process (which, as described earlier, previ- ously involved several batch coaters lined up in series) to use a single coating pan that could apply coatings quickly, enabling the machine to handle multiple sublots in rapid Table 1 Summary of process conditions used during the application of Aquarius Preferred HSP (Ashland) (20% w/w solids) using a Driaconti-T semi-continuous coater (data courtesy of Ashland) Process parameter Pan segment 1 2 3 4 5 6 7 Coating solids (% w/w) 20.0 Target weight gain (% w/w) 3.0 Dwell time per segment (min) 9 Inlet temperature (°C) 67.0 Product temperature (°C) 51.1 52.0 53.6 54.0 54.1 54.7 55.2 Exhaust temperature (°C) 53.0 (measured at segment 4) Spray rate (g/min) 44.9 46.2 46.4 44.8 44.2 44.9 44.8 Pump speed (%) 58 50 55 54 59 55 56 Atomizing air (bar) 1.2 Pattern air (bar) 1.0 Pan speed (rpm) 8 Process air dew point (°C) 0 Process throughput rate (kg/h) ~120 Figure 4 Schematic of a Bohle Koco coater Tablet deduster Tablet cores Containment valve (optional) Containment valve (optional) Coated tablets Charging blister line Unique and approved airflow of Bohle BFC/BTC coaters