Cleaning the exterior of pharmaceutical containers such as bottles, vials, and cartridges after filling prevents any adhering product residues from becoming a danger to humans and the environment. This process, which is traditionally liquid-based, consumes enormous amounts of energy and water and incurs high costs. In order to offer a dependable but more resource-friendly solution, a leading manufacturer of fill & finish machines participated in a joint project to investigate the suitability of the quattroClean snow jet technology. The results confirm that the sustainable cleaning process meets all the requirements of the pharmaceutical industry. A basic validation carried out in parallel simplifies the approval of the process in compliance with FDA and GMP regulations.
Taking on the challenges of the global market and meeting them with the best technical and most cost-effective solutions was Bausch+Ströbel SE + Co. KG.
High-tech packaging solutions including external cleaning after filling
High-quality pharmaceuticals in liquid and powder form are filled into vials, bottles, syringes, or cartridges on customer-specific filling and finishing lines in a fully automated process. This starts with cleaning and sterilizing the containers and continues through to labeling or syringe assembly.
“Due to the trend towards the use of increasingly potent active ingredients, there is a risk that the exterior of the containers could be contaminated with a potentially hazardous substance after filling. We are therefore seeing a growing demand for solutions to clean the outside of containers after the filling process. Not only do ever-stricter cleaning requirements have to be met, but the reliable removal of product residues must also be proved,” reports Werner Iländer, Group Manager of Research, Technology and Pharma Services at Bausch+Ströbel.
Dry snow jet technology instead of ultra-pure water
Until now, external cleaning has generally been a liquid-based process involving spraying the containers with ultra-pure water and subsequently drying them with clean compressed air. This requires large quantities of water to be treated in an energy-intensive process and, depending on the product being filled, to be disposed of as hazardous waste. This not only results in high operating costs for customers but is also a wasteful use of drinking water, which has already become scarce in some regions of the world.
“For these reasons, we looked around for an alternative cleaning method that would make this process more cost-efficient and resource-friendly, as well as having a lower CO2 footprint. We have been working with the dry quattroClean snow jet cleaning technology from acp systems for some time and know that very high standards of cleanliness can be achieved, depending on the substance to be removed. However, we had no valid data on the material compatibility of the process,” says Werner Iländer, describing the initial situation.
QuattroClean snow jet cleaning is a dry process for full-surface and localized applications that can be easily integrated into fully-automated production lines. The cleaning medium is liquid, recycled carbon dioxide, which is a by-product of industrial processes and used, among others, in the food industry. The liquid CO2 is guided through a wear-free two-substance ring nozzle and expands on exiting to form fine snow crystals. These are bundled by a separate jacket jet of compressed air and accelerated to supersonic speed. The easily-focused jet of compressed air and snow develops a combination of thermal, mechanical, solvent, and sublimation effects on impacting on the surface to be cleaned, which makes it highly effective.
The removed contaminants are then extracted in the compact cleaning cell, thus preventing re-contamination of the product and contamination of the surroundings. Since the crystalline carbon dioxide sublimates completely during the process, the cleaned residue-free surfaces are dry, thereby eliminating the need for costly and energy-intensive rinsing and drying steps.
Joint project provides the necessary evidence
Bausch+Ströbel therefore did not hesitate to participate in a joint project funded by Invest BW involving five industrial partners as well as Fraunhofer IPA and the NMI Natural and Medical Sciences Institute at the University of Tübingen. In the project, the material compatibility and cytotoxicity of the cleaning technology was investigated on various product surfaces typically found in the medical and pharmaceutical sectors.
“This project was primarily about proving that the mechanical forces of the snow crystals do not alter, impair, or damage the surface in any way. It was also important to establish whether the thermal stress and/or the chemical properties of carbon dioxide affect the surfaces or biocompatibility of the containers, for example by releasing cytotoxic material components,” explained the group manager.
In addition to glass vials, test specimens made of stainless steel 1.4301 and 1.4305 with different surface finishes, as well as polyetheretherketone (PEEK), polyether (PE), polyoxymethylene (POM), nitinol, and cobalt-chromium were included in the studies.
To evaluate the test series, Fraunhofer IPA examined the surfaces of the test specimens microscopically (light and/or scanning electron microscope) in their initial state and after cleaning. The dry jet cleaning process was carried out under worst-case conditions, i.e. the middle section and edges of the test specimens were continuously irradiated with CO2 snow at a high pressure of twelve bars for ten seconds. During the subsequent microscopic examination of the glass vials, no cracking was detected, and no propagation of existing cracks was observed. With the aid of a fluorescent penetrant, it was also possible to demonstrate that the snow crystals did not cause any additional stress in the glass. Likewise, the abrupt exposure to cold and the subsequent warming of the vials to ambient temperature did not result in the formation of any micro cracks.
GMP- and FDA-compliant process
The process therefore meets all the requirements of the pharmaceutical industry in this field; it is also compliant with GMP and FDA in terms of material compatibility, meaning that basic validation has already been achieved.
“In this project, we were able to generate the key data for our customers and develop a basic solution. The next step will be to implement this in a market-ready product that will significantly reduce operating costs and resource consumption in external cleaning for specific applications,” adds Werner Iländer.
