Design is key: What are the important considerations in tablet production?
Steve Osborne, I Holland’s product design manager, looks at some of the important considerations to be taken before tablet production.
Oral solid dose is still one of the most popular forms of delivery and this is for a number of reasons from ease of use, portability, administration and accuracy in dosing. As so many billions of tablets need to be produced quickly and efficiently, the requirement for tablet manufacturers to look at design specifications prior to processing should be a primary consideration.
Swallowability — do size and profile matter?
The ‘swallowability’ of the tablet can be affected by the design and profile of the form being produced. Difficulty swallowing tablets and capsules can be a problem for many. According to a survey1 conducted in 2014 on patients in Germany and the US, over 55% of people from all age groups and genders experience swallowing difficulties when taking tablets. Individuals who find it difficult to swallow tablets and capsules frequently cite the size as the main reason for the difficulty in swallowing. Size and shape of tablets affects transit of the product and may directly affect a patient’s ability to swallow a particular drug product.2
With this in mind, it is important to pay attention to the design of the tablet before production, not only for the end-user, but it is also important to the final quality of the tablet and ease of production.
Tablets are becoming more complex in both shape and profile for brand identity and marketing purposes. As the tablets become more complicated, so does the tooling, increasing the demand upon tooling strength, durability and overall performance.
The correct tablet shape and profile is key in finding a successful end product that can be easily manufactured. There are two basic tablet shapes, round and non-round. Non-round shapes are extremely varied and designs may require specialised tool manufacturing capability. Choosing the wrong shape (or a shape that has been badly designed) can have a huge impact on the bottom-line as problems like sticking and picking can result from this and will delay production.
Once a workable base shape has been decided, tablet size must be determined. Consideration should be given to the type of press available as this can limit the size of the tablet. Also, is it possible to produce the tablets using multi tip tooling? Multi tips can accommodate most tablet designs, but this is influenced by the press and tool type capabilities. You must look at the tablet size to evaluate the number of tips to fit the punch; some shapes can be more challenging to arrange so that they take off cleanly and efficiently.
Tablet profile is the next important consideration. The profile is affected by a variety of aspects, from the granule being used and the influence it has on the tooling, through to the embossing requirements, and coating process.
If the design is to be heavily embossed it is important to avoid tablet profiles with a deep cup, such as the ball or pill. Deep cup profiles can cause a softer core in the tablet which, in turn, can lead to sticking and/or erosion. It will also reduce the available space for the embossing itself.
Using a profile that is shallower, with a reduced cup depth, will allow for a larger embossing area.
Do you require a coating on the tablet? A coating may be aesthetic or intrinsic but can also help in swallowability, and so this requirement should be incorporated during the initial design. Successful coating is largely dependent on tablet profile. As discussed the centre of a tablet is normally softer, so during the coating process core erosion may take place. This vulnerability, caused by mechanical stress during coating, can be reduced by avoiding very deep concaves and ensuring a robust design.
Breaklines
Breaklines that are used to divide a tablet must be both functional and effective. Uneven breaking of a tablet may result in significant fluctuations in the administered dose. The degree of inaccuracy may be associated with breakline design, tablet hardness and/or formulation.
Several factors should be considered when incorporating a breakline. The tablet’s size and hardness should be addressed so the end-user can easily hold the table when breaking. Care should also be taken to ensure that the breaklines match on upper and lower punches. Thought should also be given to branding as logos can have an influence on the breakline. Product identification should also be maintained to ensure brand integrity when the tablet is divided.
Tooling performance
When looking at performance, consideration should be given to the tools’ ability to manufacture tablets that are representative of a manufacturer’s design requirements and product yield.
Selecting a design that is aesthetically pleasing but will not stand up to the demands of tablet production will waste time and money. Look at the choice of tooling material and coating, is it appropriate for the formulation being compressed? When a cycle is complete are the tool maintenance procedures optimised for ensuring prolonged tooling life? Can the design withstand prolonged cyclic loading and fatigue to produce a well compacted tablet? This is even more important when specifying a requirement for multi-tip tooling.
All these questions are fundamental and should be advised by a quality tablet designer. Examination of any previous tablet production, tooling audit and management should also be considered.
Design is key
The design of a tablet is crucial to a well-made end product. Without considering basic but important design processes like shape, profile and breakline, the tablet will simply not work. Professional tooling designers can take all these variables into account during the initial design and concept stage, resulting in an easily manufactured quality tablet.
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