PHARMA FOCUS//Tabletting & Encapsulation and a 35° angle. Most product formulations should be readily compressed into tablets using tools with this engraving design. To reduce or eliminate material picking in the centre island, pre-picking can be incorporated in the design. This is illustrated in Figure 3 where the depth for the island is reduced from 0.33 to 0.17mm, defined as a 50 percent pre-
Figure 4: Pre-pick and taper on a round tablet
Figure 3:Pre-pick of the engraving on a round tablet
pick. The amount REFERENCE:
of reduction can
1. Sedlock R, It’s all in the detail, European Pharmaceutical Manufacturer 16(2): pp16-7, 2016
range between 10 and 100 percent, depending on the extent of the problem. For branding or aesthetics, tablets coated after compression must be taken into consideration, as excessive
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pre-pick will significantly reduce the clarity of the logo. The partial pre-pick concept is applicable to any letter or numeral with fully enclosed areas called ‘islands’ or ‘pads’. Complex characters that do not have fully enclosed areas – like E, S, K and M and numerals like 2, 3 and 5 – are also prone to picking and require tapering or ramping as a prevention measure. Having peninsulas tapered between 10 and 50 percent of the engraving depth is usual, with 30 percent the most common. An example of a 50 percent taper is illustrated on the right side of Figure 4.
Tooling construction materials If the sticking and picking are discovered during R&D or if it’s time to order the next set of punches for a product with known sticking and picking issues, consider having the punches made from a speciality steel. Punch steel with
PARTNER WITH THE GLOBAL LEADER IN TABLET COMPRESSION TOOLING:
a high concentration of chromium in the alloy chemistry, usually between 16 and 18 percent, enhances release of the compressed product. Applying a coating to standard steel punches to enhance the release characteristics of the punch faces is another alternative. The most common coatings are hard chrome and
• Tablet Presses • Tooling • And Ancillary Equipment
chromium nitride. Bear in mind, the thin chrome coating layer may wear off over time due to the abrasion of the formulation and polishing. So, the better long-term choice may be a high-
Representative for Southern Africa:
chrome steel without coating. Ultimately, several remedies can help speed a new drug to market, ranging from slight formulation changes to major tablet design and tooling modifications. When developing a to-market strategy, early consultation with a tooling vendor like
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Natoli Engineering is best. Insights from the Natoli Engineering
The one-stop shop for tablet compression tooling.
technical team or its agent in southern Africa, Formpak, will benefit the final product and help create a tablet acceptable to both the manufacturer and consumer. •
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