Just as good tablet design is extremely important in the manufacture of pharmaceuticals for humans, the same applies for animal dosage forms. Tablets are used to deliver drugs in an effective and safe manner, and although less dominant in veterinary medicine, tablets or boluses are still a significant method to administer medication. Getting tablet design correct has an impact upon anticounterfeiting, tooling strength, tablet coating, durability and functionality. It also helps to avoid downstream manufacturing problems such as tablet sticking, picking, lamination, capping and premature tooling failures. It is essential to consider these at the beginning of the design process, ensuring a problem-free, high-quality end product. Several elements need to be considered when designing tablets for animals; here we will consider the most important.
Tablet Shape and Profile
The first thing to consider is the tablet shape and optimum tablet profile. There are two basic tablet shapes, round and non-round; however, the complexity of non-round shapes can be very varied and require specialised tool manufacturing capability. Boluses, which are commonly used for large animals are cylindrical shaped to prevent choking. Due to their size (typically 3 to 16 g) it is important to get the shape correct. ‘Bolus formulation poses challenges because of the high drug-to-excipient ratio. Less room is left for diluent, binders, and other adjuvant needed to overcome objectionable features of the drug or to facilitate bolus manufacture.’
These higher numbers of active ingredients in animal formulations bring challenges related to particle size, flow, compressibility, moisture sensitivity, ingredient interaction, content uniformity and quality control (QC) testing. For example, some active ingredients may be available in granular form, while some may be available only in fine powder form. Because of this, the ingredient blend may have many different particle sizes and ingredients with a variety of characteristics. This variation demands the shape and profile to be correct during manufacture.
Once the base shape has been decided, tablet size must be determined. Consideration should be given to the type of press available for tablet manufacture as this can limit the size of the tablet.
Next follows a selection of the tablet. The type of profile required is influenced by several factors: the granule, embossing requirements, coating process, packaging and the company’s branding.
Thought should also be given to the volume of the tablet and if it will be coated. Successful coating is dependent on the tablet profile. Coated tablets, whether film- or sugar-coated, present challenges for the tablet designer. The complexity of the coating process is vast. Many of the variables are within the manufacturer’s control but expert tablet design can help eliminate some potential problems.
Coated tablets are a popular choice in animal medicine. Administering tablets to animals is not a guaranteed process due to the uncertainty of the tablet being swallowed. Many animals also chew the tablet, exposing the disagreeable taste of the drug. For this reason, flavours or sweeteners are combined or a coating is used. ‘Tablets can be coated to differentiate the product by colour, to help mitigate offensive tasting compounds, or to prevent dusting in the bottle.’