An even coat: How to achieve the perfect tablet finish
The film coating process requires a balance of the complex interactions between the tablet substrate, coating system, coating process and equipment. In this feature Jason Teckoe, technical director, EMEA at Colorcon discusses the importance of choosing the right formulation and managing the coating process to ensure process efficiency while delivering a perfect tablet finish.
Tablet Film Coating Scale-Up & Tech Transfer
A frequent challenge for manufacturers is scaling up to different coating equipment while maintaining reproducible coating quality. It’s common for issues not predicted earlier in development to become apparent in real-world settings.
A key part of technology transfer is scale-up, with studies to take the optimised, already-developed process and transfer it to various equipment types and sizes - often at other manufacturing sites. In some cases, it can involve further optimisation of parameters specific to the manufacturing site or a particular piece of equipment. Also, as older processes or equipment are improved, coating parameters sometimes change. This is not uncommon when shifting from a conventional type of coater (solid-pan) to a perforated pan (auto-coater), or when transitioning from batch coating to larger scale continuous or semi-continuous coating equipment.
Identifying Critical Process Parameters of Film Coating
There are several variables, often inter-dependent, that can influence both the coating process and the quality of the final coated substrate. During scale up, you’ll need to identify all the critical process parameters. The objective is to understand the importance of each parameter to achieve your required quality and functionality at the desired scale of operation.
These critical parameters need to be controlled within limits that allow the final process to be operated routinely in a manner that yields an optimal product within acceptable time & cost constraints.
Reducing Risk During Tablet Coating Scale-Up
Achieving a perfect finish for your coated tablet comes down to ensuring the right coating formulation and process parameters are used, whatever the scale.
One of the major differences amongst coating machines is air flow capacity. For example, in the Asia Pacific region and some parts of Europe, coating equipment tends to have much lower airflow than that in North America. Other regions still use many conventional solid wall pans, which have low airflow and poor temperature control. The coating formulation needs to be flexible and robust to withstand these types of variables and still result in a uniform, high-quality final appearance that does not vary from batch to batch. Even with limited air flow, Opadry QX has been proven to consistently deliver a smooth, glossy tablet finish.
At Colorcon, we’ve conducted multiple studies to identify and characterise the impact of varying key coating process parameters on critical quality attributes for all our formulated coating systems. This helps manufacturers to be confident their process will be reliable through scale-up and transfer, even across different types of equipment.
Choosing the Right Coating
Opadry QX – a recent Colorcon technology advance – is designed to simplify tech transfer and scale-up as it can be easy to use across a wider range of process variables. Where many coatings require narrow windows of operation, Opadry QX delivers excellent results across much wider ranges. In addition to being forgiving across variable parameters, it is effortless to work with and delivers better coating consistency with process efficiency.
And, with quick application to protect from the rigours of the film coating process, Opadry QX is enabling manufacturers to easily coat temperature sensitive actives. Designed for use across a wide range of equipment, with tablet bed temperatures as low as 30°C, the high solids levels mean a perfect coating finish is completed in 40% less time. This exceptional process adaptability means coating scale-up and transfer to production is simpler, saving time and valuable resources, while still delivering a premium quality finish.
The commercial impact of the process and equipment flexibility means that pharmaceutical companies can easily transition the manufacture of drug products across sites, and continents, overcoming challenges often met with equipment differences. Capital investment may also be deferred through more efficient equipment utilisation as production needs increase.