Single-Pot Processors

FIGURE 7 Single pot processor. Source Courtesy of Patterson-Kelley. 

Powders loaded into the single-pot processor are dry-mixed until appropriate uniformity is achieved after mixing, the binder solution is sfxayed in and wet massing ensues. Factors normally associated with the granulation process such as spray rate and volume, droplet size. 

TABLE 4 Some Commercially Available Single-Pot Processors... 

Figure 10 Schematic view of a single-pot processor ULTIMAPRO based on the ULTI-MAGRAL with a vacuum dr5dng system. (Courtesy of Niro Pharma Systems.)...

Figure 1 UltimaPro 600 microwave/vacuum single-pot processor with swinging bowl. (Courtesy of Collette NV, Belgium.)...

Figure 2 L.B. Bohle single-pot processor. (Courtesy of the L.B. Bohle Group, Germany.)...

Requirements for solvent recovery systems are lower for single-pot processors compared with fluid-bed driers. Single-pot processors outfitted with vacuum are attractive for evaporating events that are explosive or for containing drug substances... 

DRYING METHODS FOR SINGLE-POT PROCESSORS 3.1. Conductive Drying... 

Because of the different technologies incorporated into a single-pot processor, it is capable of executing many different processes, apart from the standard wet granulation and drying process, while small modifications or additional options can extend the flexibility even further. 

This chapter discusses some of the possible special processes and applications in a single-pot processor. Although many of these processes are used in the pharmaceutical industry, scientific literature on them is rare. The main reason for this is that many of these processes were developed by the pharmaceutical industry as product-specific solutions. This does not imply, however, that these processes cannot be used more widely. 

If the meltable binder used absorbs microwaves, however (such as PEG for example), using a single-pot processor equipped with microwave drying can present major time-savings to the production process. 

However, the results from the previously mentioned study show that it is worthwhile to consider a single-pot processor for the production of melt granulations. 

There are, however, many references in scientific literature detailing the production of pellets using a high-shear mixer, most of which concern melt pelletization (15-21). Taking into account the explanations given earlier on melt granulation, a single-pot processor can, of course, also be used for this process for the same reasons. 

For the one-step granulation methods, the use of a single-pot processor offers many benefits. Apart from the overall benefit of eliminating product transfer between a granulator and a dryer, a single-pot processor allows easy solvent recovery by condensation in case organic solvents are used as granulation liquid, compared to the quite complex system for the exhaust gas treatment required for a fluid-bed dryer. 

When water is used as granulation liquid for effervescents, the effervescent reaction will start and cause a chain reaction. The critical point in such a process is to stop this reaction at the correct time by evaporating the water created by this reaction. In a single-pot processor, this can be very easily and accurately achieved by switching on the vacuum-drying system (possibly supplemented with gas-assisted drying or microwave drying) (24). 

As a single-pot processor is often used for highly potent products, or more generally for contained production, it is important that also cleaning of the machine can be executed in a contained, automated fashion to eliminate the risk of operator exposure to the active product. 

Drying of the single-pot processor after the cleaning cycle to prepare the equipment for the next batch can be done using the system s own vacuum-drying system and jacketed bowl, making a separate drying unit redundant. 

A nice case study of an evaluation of a clean-in-place system on a pilot-scale single-pot processor is given in Ref (3). In this study it was proved that a complete changeover from one product to the next can take place in <2 hr. 

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