The US Food and Drug Administration (FDA) attracted considerable attention when it sent a Warning Letter that raised questions about why so many out-of-specification tablets are still distributed despite strict regulations and modern technology. In a White Paper Fette Compacting investigates the possible causes and offers advice on the optimum use of tablet presses.
Many manufacturers are struggling to manage variations in the weight, hardness and size of their tablets: the FDA issued 42 Warning Letters involving the recall of tablets between 2008 and 2011 alone. Unfortunately, analysis of FDA investigations has not found a single, easy-to-solve reason for the fact that deficient tablets have reached the market despite all the regulatory procedures and authorities.
Not one single cause, but a collection of causes
Analysis indicates that two groups of causes are responsible for the distribution of out-of-specification (OOS) tablets. On the one hand, operating errors by plant managers and machine operators and, on the other, outmoded and/or deficient technical components in the tablet presses themselves.
Training reduces errors
Modern tableting machines are equipped with safety mechanisms that make accidental or intentional operating errors almost impossible. For example, password-protected parameter input prevents unauthorized changes in machine settings. Nevertheless, tablet presses are production machines with numerous parameters. It is therefore advisable to qualify operators and process managers in certified training programmes by machine manufacturers. That minimizes operating errors. Another cause of OOS tablets is raising operating speeds to increase tablet output without making appropriate adjustments elsewhere. Since production processes are very finely coordinated, such interventions can soon have unforeseen consequences.
Modern test systems supply comprehensive quality data
When it comes to sorting out “bad” tablets, manufacturers have made huge technological advances in recent years. Used correctly and fully integrated into the production process, external automatic tablet testing systems, for example, can supply detailed analyses of the weight, hardness, diameter, thickness and active ingredients of individual tablets. However, the integrated weighing unit must be regularly calibrated to ensure the long-term quality of data.
Data gathered by testing systems is fed back to the tablet press, where automatic tablet sorting then goes into action: while older machines still use slow and error-prone mechanical sorting diverters, compressed air jets are used to channel the tablets in more up-to-date machines. They precisely steer the tablets into good and bad channels.
The recommendations made here and additional detailed advice on the subject of “Best Practice for Tablet Quality” are covered in detail in the current Fette Compacting White Paper. You can download the white paper here: