New drug development is today focused largely on biopharmaceuticals rather than chemicals, which means that the resultant drugs tend to be injectable liquids instead of solids. Furthermore, the new drugs are typically designed for specific populations, hence batch sizes are smaller. Alongside these two trends there are ongoing pressures to increase efficiency, reduce costs, and minimize risks — including cross-contamination between batches. Additionally there is a need for a reduction in the time involved in validation procedures; paperwork and man-hours, for example. Taken together, these factors point towards peristaltic pumps with single-use tubing or tubing sets as representing the future for bio-pharmaceutical fill/finish lines.

Traditionally, fill/finish lines have used piston pumps but, in today's production environment, piston pumps suffer from a number of drawbacks. One of these is that piston pumps contain numerous contact parts that must be dismantled, cleaned, and sterilized between batches of different product. As batches become smaller, there is a need to shorten changeover times. Even if duplicate pumps are purchased to achieve faster changeovers, each pump still needs to be stripped, cleaned, and sterilized — and a small risk of cross-contamination between batches will always remain. In contrast, the only component of a peristaltic pump that comes into contact with the product is the tubing. If the tubing is a single-use item that is supplied presterilized, the need for cleaning and sterilization is eliminated, as is the risk of cross-contamination.

Production managers switching from piston pumps to peristaltic pumps are often surprised at the accurate, pulsation- free flow that peristaltic pumps achieve. In addition, sophisticated electronic control of the pump motor enables the flow rate to be ramped up, maximized and ramped down again, thereby reducing aeration and foaming so that very short cycle times to be maintained. It is not unusual for peristaltic pumps to be used on filling systems processing up to 150 bottles per minute.

With appropriately sized tubing, peristaltic pumps can deliver volumes down to 0.5ml at an industry-standard accuracy of +/-0.5 percent; smaller volumes can be delivered with an accuracy of +/-1 percent. Typical high-speed filling machines use in-process checkweighing to monitor the filling accuracy and, if necessary, the output from this can be used in a closed-loop pump control system.

Varying the pump speed is one way to change the flow rate, but peristaltic pumps can also operate with different sized tubing. This can be beneficial in applications where a facility produces a range of substantially different batches. Although it is an extreme example, a single peristaltic pump can fill volumes between 0.1ml and 250ml simply by changing the tubing size.