Vial Stoppers That Won't Stop Clumping

Sep 21, 2011
By Pharmaceutical Technology Editors
Untitled Document

Q: In our manufacturing process, we are running into issues with our vial stoppers clumping in the feeder bowl. How can we ensure that the stoppers go through smoothly without clumping up?

A: Clumping can result from various issues. The design of lyophilization stoppers can lead to twinning, a condition where the closures’ legs interlock and remain that way during processing. Autoclaving in an inappropriate container or in a container that holds closures too tightly may also result in twinning. Inconsistent siliconization and overprocessing can lead to clumping. If stoppers are autoclaved or dried too long, excessive heat may break down the elastomer. The result is a bowl full of tacky stoppers.

When clumping occurs, manufacturers must first examine the type of stopper they use. It may be time to move to a newer product, such as ready-to-use or ready-to-sterilize stoppers. Suppliers of these components use validated processes to prepare pharmaceutical closures that help manufacturers streamline operations by eliminating component-preparation steps, such as washing, sterilization, and siliconization. When the packaging manufacturer performs this preparation, it can help ensure that closures are consistent. Products with barrier films or coatings may also ensure smooth processing by reducing clumping. Films and coatings also help prevent stoppered vials from sticking to the shelves of lyophilization chambers. Purchasing new stoppers will not fix the current problem, but may help to prevent future issues.

Manufacturers may need to review and adjust their processes, including washing, sterilization, and siliconization, to avoid overprocessing. If stoppers are sticky after autoclaving, reassess the autoclave conditions and validate the process at milder conditions. A process lasting no more than one hour with 121 °C steam heat (or no more than 8 h with 105 °C dry heat) should ensure that the product is not harmed by excessive heat. If the problem stems from the process flow, manufacturers should contact a technical support representative.

—Gene Polini, principal technical account specialist at West Pharmaceutical Services


If you have a problem with your equipment or process, an industry expert may have the solution. Please send your question to Erik Greb, editor of Equipment and Processing Report, and we may be able to provide an answer in a future issue. All questions will remain anonymous.

lorem ipsum