Case Study: Assessing the latest coating tech
Automated solutions provider IMA Group outlines its collaborative study with chemicals company BASF on how it assessed its latest coating technology.
When deciding on a particular coating technology, manufacturers must consider both the quality and economic efficiency of the process. Consequently, process time and coating uniformity of the final product have to be considered, especially within the realm of functional coating and/or drug layering.
Automated solutions provider IMA Group recently conducted a study alongside chemicals provider BASF to evaluate the efficiency of its Perfima Edge coating technology during the pellet coating process.
Experimental Methods Materials
The company used pellets consisting of sucrose and microcrystalline cellulose as a substrate, before applying Riboflavin embedded in a film of PVA-PEG graft copolymer (Table 1). The functional coat was based on Kollicoat Smartseal 30 D (BASF) – a polymer delivering taste masking functionality due to its pH dependent solubility[1]. Other components of the formulation (Table 2) include FD & C Blue No. 1 (BASF); acetyl tributyl citrate (ATBC, Jungbunzlauer); buthylene hydroxy toluene (BHT, Sigma-Aldrich) and talc (Merck).
Equipment
The study assessed the Perfima Edge side vented pan coater (SVP) which was equipped with wedge wire screen drum, specifically designed for coating of small substrates such as pellets. Small wedge wires were fitted into the drum to allow the passage of air during the process. The equipment maintained the same drum shape, drum geometry and spray system of the standard equipment for tablet coating. To handle all types of substrates in regard to shape and size, specially-designed mixing baffles were welded to the centre and the side walls of the drum. The coating trials were conducted according to schema reported in Table 3.
Methods
Photometrical measuring
To determine the individual amount of applied coating, IMA and BASF used photometrical measuring of either Riboflavin or of the colorant FD&C Blue No. 1. This was done to allow a distinct investigation on the coating level.
Dissolution testing
Standard equipment according to Ph. Eur. was used for the dissolution test. Phosphate buffer (pH 6.8) was used as dissolution media, due to taste masking function being delivered in the oral cavity. The criterion for a fully functional coat was that no drug release was seen for a period of two hours.
Weight gain
The weight gain of the pellets was calculated according to the equation in Figure 1.
Results and Discussion
In a first coating step, Riboflavin was applied as a tracer for the dissolution testing. The achieved weight gain revealed optimal performance as showed by employing standard deviation as scale for content uniformity (Table 4).
Kollicoat Smartseal 30 D based formulations have to be applied onto tablets with a typical coating level of 3.5 mg/cm² to gain full functionality (meaning no drug release for 2 hours in neutral media) [4]. When applying a comparable coating formulation (Table 2) onto pellets, full functionality can be achieved with distinctively lower coating levels (Figure 2). The reason for this is the critical edge between band and cap which every tablet bears inherently. However, pellets with a spherical shape do not offer such crucial areas, meaning reliable functionality is achieved at lower coating levels.
Due to the mixing properties of the baffles fitted on Perfima Edge, the release profiles become more and more similar at higher coating levels. This demonstrates that both coating performance and efficiency will be eventually equal.
Conclusion
The results of the study exemplified the small footprint of the Perfima Edge as a space-saving alternative to fluid bed technology. More so, the design allows optimal accessibility of the processing, whilst up-scaling is quick and relatively simple. IMA Active’s wedge wire screen drum was shown to be efficient and able to coat in the same pan cores of different size and shape, the researchers found.