How to tackle a sticky issue
The issue of material adhering to the punch face and die wall in the production of tablets is one of the most common issues faced. As a result, a number of companies have invested in tackling the issue.
Among them is I Holland, which teamed up with the University of Nottingham in an attempt to find a solution to the issue. The work from this partnership has already come to fruition, with the development of the PharmaCote range of solutions for the industry.
Rob Blanchard (RB), R&D manager at I Holland, was the driving force behind this partnership and he spoke to in-PharmaTechnologist (IPT) about how many companies in the industry are still facing the same problem, despite knowledge of the area progressing significantly over the last decade.
IPT: How large of an issue is sticking for the industry?
RB: I can quite confidently say that, “We've got a sticking problem, how can we solve it?”, is one of the most common questions we hear. Every time we do a seminar, or every time we do a webinar, the vast majority of the questions are linked to sticking. You do get a lot of interest in the topic because it clearly is and can be a real problem to manufacturers.
IPT: What issues does it cause?
RB: When it occurs, it ruins the tablet, it slows production down, as the company will have to stop the press often to clean the tooling. It causes problems downstream because it can cause issues with tablet coating. You can get problems with the potential breakage of the tooling and you can get weight variation in the tablet. It causes so many issues therefore everybody's looking at it and ways of stopping sticking.
IPT: How are most companies addressing the issue?
RB: The best way is to stop it occurring before it starts, by being proactive rather than reactive. However, as this is not always possible, we've got very good reactive fixes and, as a tooling supplier, we've got a toolbox of solutions that can solve the issue.
By far the best way of solving sticking is by quality by design at formulation stage, but that's not always possible and we have to understand that as well. Sticking is not just an issue at new product development stage, it can still occur at product transfer and then there really is no choice – you have to be reactive. I guess it's a little unfair to say that the biggest problem is everybody's reactive because you can't always be proactive.
IPT: Why do the issues occur?
RB: There's lots of reasons for this. If we start with product transfer – companies regularly transfer products from one site to another and that can cause all sorts of problems. This can happen because they're not familiar with a product, they could be moving it from an environment where it's not humid and it's not hot, and it's an ideal environment to produce the product.
Also, when you've got product transfers then the excipients can change. The spec will be the same and it'll be within tolerance, but it'll be from one end of tolerance to the other – and that can cause sticking.
We're also seeing a bit of a trend towards dual APIs in one tablet. We all know that's it’s great for the patient to be able to take just one tablet per day. But, the problem is that if both APIs are sticky then the percentage of the sticky ingredient in that same size tablet goes up. Therefore, the excipients that are there to combat sticking can't have the same effect because there's more API, the percentages is higher, so that they struggle to do their job. So, we've seen scale up issues with dual therapy drugs.
IPT: How does I Holland work to prevent these issues?
RB: I Holland have solutions for every one of the root causes nowadays, but that doesn't mean to say that we can't improve them. This is where we are now – it is more of a refining process. We've got a good range of products within our PharmaCote range that can be applied to tooling that solve those root causes.
IPT: What is a major trend that you're noticing in the industry?
RB: Continuous manufacturing is one, and there's a lot spoken about continuous manufacturing in the industry at the moment and moving away from batch manufacturing. So, there's no lost time waiting for shutting one process down and waiting for another before you can start the next batch. When you're talking about continuous manufacturing, if sticking has occurred at compression stage and stopped a line then it is likely to be a bigger problem.
Since joining I Holland in 2003, Rob Blanchard has been instrumental in the development of I Holland’s PharmaCote range of surface treatments and coatings for tablet compression tooling. Blanchard combines R&D with quality, and co-ordinates I Holland’s close collaboration with various respected academic research bodies, including Nottingham University.