GEA technology offers increased tablet coating and drying efficiencies
10 Nov 2020
Designed to gently and accurately deposit controlled amounts of coating materials onto tablet cores — even if they are hygroscopic or friable — the high-performance GEA coater technology is able to process both small and large quantities of tablets at very high suspension application rates.
The operating principle of the GEA coater is based on a conventional pan and spray system, but the way the object — the tablet core — is being presented to the coating spray has been improved. The fundamental principle of the film coating process remains unchanged. Incorporating a small, simple and modular design, tablet cores (from 3 kg upwards) are loaded into a perforated wheel and are formed into a ring by rapidly accelerating the wheel to high speed. Once the ring is formed, radially placed air knives induce the tablet cores into a stable, free-falling cascade, presenting the tablet cores to the coating suspension, which is sprayed in a vertical plane. The animation below shows how the system operates.
The drying efficiency is increased by spraying the coating suspension into the cascading cloud of cores. As such, the process is much faster, offering a target weight gain of 3% (15% solids content) in less than 10 minutes — compared with at least 90 minutes in a conventional pan coating process.
Compliant Coating
In the highly regulated pharmaceutical industry, compliance is critical. According to the US FDA’s SUPAC Guidelines, however, it’s often the process that is subject to stringent validation criteria and not the machine itself. For instance, it is acceptable to use either a top-drive, bottom-drive or side-drive granulator for the same application as long as you can prove that the technique is compatible and falls within the guidelines.
And, according to SUPAC guidelines, using the GEA coater is considered to be within the same definition as a traditional pan coating process, only the speed and manner of tablet presentation have been improved. You can validate the same type of process using a wide range of different pan coaters and no re-registration is required. With the GEA coater, the USP is that the rate of rotation has been increased from, say, 10–15 to 100 RPM. According to SUPAC, though, it conforms to the definition of a rotating perforated coater.
Studies performed with Colorcon, for example, demonstrated that the way that the core is exposed to the spray in the GEA Tablet coater achieves a more uniform coat, which means that, to achieve the same level of uniformity as a pan coater, less coating material is used. In addition, color variations between tablets are reduced to almost negligible with just a 2% coat (normally requires a 3% or greater weight gain with a conventional pan or Wurster coater system).
In Figure 1, for example, it can be seen that with a 2% weight gain, the colour uniformity is well below the level that can be observed by the naked eye.
Figure 1: Color Difference from Reference Target at 1%, 2% and 3% Theoretical WG (Case study with Opadry QX (Colorcon) – ref. 6)
A key point is that a 3% weight gain can have a significant, possibly adverse, effect on a 200 mg core compared with a 1500 mg one because the surface areas are completely different. With the GEA Tablet coater, it’s possible to achieve the same level of color uniformity with just a 2% weight gain. Moreover, GEA researchers have looked closely at different tablet images, including unusual shapes, and how these cores move and tumble in a regular pan coater (Figure 2). They often “twin” or come together and they’re difficult to coat. With the GEA Tablet coater, these issues are overcome and the same level of color uniformity is obtained with much less coating material.
Furthermore, the GEA coater enables a faster process for enteric coatings owing to the improved uniformity of the coat: a 5% weight gain using the GEA coater produces the same enteric performance as a 12% weight gain when using a batch machine (Figures 3 and 4), which represents a 60% saving in materials.
Figure 2: Examples of tablet shapes successfully coated with the GEA Tablet coater
From a regulatory perspective, the GEA Tablet coater is a rotating coater and fully compatible with SUPAC Guidelines. From a customer viewpoint, the benefits are predictable throughput and operating conditions — obtained through heat and mass balance modeling, excellent color uniformity at lower weight gains, more flexibility for enteric and sustainable release coating formulations, fast drying times and improved process efficiencies.
Offering both batch and continuous functionality, very short processing times and superior film-coat layer uniformity, the GEA Tablet coater is also able to accurately coat expensive modified release formulations using up to 60% less material. During development, smaller amounts of coating are required as Design of Experiment (DoE) tests can be done with less material, such as a batch size of 3 kg. Traditional batch technologies normally require large pan loads. And, as the GEA coating process is inherently “continuous,” the concept of scale-up is eliminated; the maximum “batch” size is almost infinite.
Figure 3: Dissolution profile of 325 mg aspirin tablets at 5%, 6%, 8% and 10% Enteric coating using Acryl-EZE ® from Colorcon (ref 10)
PAT-compatible, the GEA coater is easy to clean and offers significant cost savings compared with conventional systems in terms of time, materials, downtime, scale-up, process revalidation, stability testing, etc. Plus, with a smaller technical space requirement than established technologies, less cleaning and a reduced plant area is needed. The GEA coater has a very low energy requirement and, as well as being available as a standalone unit, can be incorporated into both existing batch or continuous production lines.
The GEA coater can also work with advanced digital tools to facilitate the development and optimization of process requirements without the need for experimentation using a digital twin. The coater is also supported by a fully interactive virtual reality training tool that will improve operational activities in terms of set-up and disassembly.
Figure 4: SEM images of a coated core using a traditional and GEA coater; data generated in collaboration with Colorcon Inc. using Acryl-EZE® as the coating material
In collaboration with different suppliers of coating materials, ongoing studies — including digital modelling and detail assessment — are currently underway at GEA as we further examine the benefits of this coating technique and continue to develop complementary digital models. Aiming to optimize both the enteric coating process and provide a virtual reality environment for training and dis/assembly, keep an eye on this blog space for upcoming announcements about our portfolio of services and how the GEA coater can benefit your application.
Bibliography
1. Ashland Technology Symposium 2015 (Wilmington, DE) “A Novel Tablet Coating System to Support a Continuous Tableting Line,” A. Birkmire
2. PBP 2015 (Lisbon, Spain): “A Novel Tablet Coating System to Support a Continuous Tableting Line,” A. Birkmire
3. IFPAC PR 2015 (San Juan, PR): “A Novel Tablet Coating System to Support a Continuous Tableting Line,” A. Birkmire
4. AIChE 2015 (Salt Lake City, UT): “Exploring the Design Space of a Novel Tablet Coating Process to Support a Continuous Manufacturing Line,” A. Birkmire
5. AAPS 2015 (San Diego, CA): “Application of a high-Solids Film Coating System Using a Continuous Tablet Coater,” C. Cunningham
6. AAPS 2016 (Denver, CO): “Application of a Developmental, Highly Productive Film Coating in the GEA ConsiGma Tablet Coater,” C. Cunningham
7. IFPAC 2016 (Arlington, VA): “In-Process Monitoring of Tablet Critical Quality Attributes in a Continuous Tablet Coating System,” A. Birkmire
8. AIChE 2016 (San Francisco, CA): “Examination of Coating Process Adaptability Using Opadry® QX in the GEA ConsiGma® Coater,” A. Birkmire
9. IFPAC 2017 (Arlington, VA): “In-Process Monitoring Using Raman Spectroscopy in a Continuous Tablet Coating System,” S. Gilliam
10.AAPS 2013 “Investigation of a New Semi Continuous Coating Process using a fully formulated Enteric Coating system” C. Cunningham
