Advanced coating technology for packaging

Dr Claudia Dietrich

The pharmaceutical industry invests billions towards research on new drugs with ingredients like monoclonal antibodies, therapeutic proteins or small molecules. This also calls for looking into how to package and store new sensitive active ingredients most effectively. Here, safety and quality are at the top of the priority list. Undesired interactions between drugs and pharmaceutical containers that induce adsorption, aggregation or limited stability of active ingredients should be avoided. Also the occurrences of "leachables and extractables" are examples of issues that are currently of interest. These elements that are invisible to the human eye can detach themselves from pharma packaging over time and can, thus, interfere with effectiveness of medication stored inside. One approach to improving chemical stability of these packaging materials and, therefore, shelf life of the respective medication, is to apply extremely thin barrier layers to the inside surface of the pharma container.

To do this, SCHOTT developed a special technique back in the 1980s that the company had patented on a worldwide basis—PICVD (Plasma Impulse Chemical Vapour Deposition) with the brand name "SCHOTT PI Coating".

Here, high quality glass vials made from "SCHOTT Fiolax" glass tubing are first washed at 70°C, using pure deionised water, and then dried.

During the next step, a coating that is only 100 to 200 nanometers thick is applied. To deposit the reactants onto the surface of the containers a procedure including pulsed energy and plasma was created. The result is a coating with bonds covalent to the surface of the container without dimensional or optical changes of the pharma containers. This coating also resists normal pharma procedures like sterilisation, autoclaving or depyrogenisation. PICVD is a validated process with permanent inspection of the reactors, a permanent checking of process parameters and a permanent system monitoring.

SCHOTT has been coating containers that the company sells on a global basis under the brand name "SCHOTT Type I Plus" at its site in Müllheim (Germany), since 1997. These coated vials reduce ion leaching of sodium, calcium, boron, silicon and aluminium with an improvement factor of 15 to 350 in comparison to non coated containers. Other than previous treatments to avoid extractables, PICVD shows no risk of sulphate or reagent residues and no risk of protein aggregation on silicon particles because of its chemical bonding properties. So this is the ideal solution for packaging of highly concentrated proteins with limited stability like monoclonal antibodies.

Vials with so-called hydrophobic coatings that are also manufactured using the PICVD technique are the latest coating product of SCHOTT. Initial samples of these products are currently being sent to interested customers. Hydrophobic, in other words, water-repellent coatings show an extremely smooth surface.

In fact, freeze-dried substances find it difficult to cling to the container surface. The advantage of this coating technique is a homogenous and elegant "freeze-drying cake" with less disruption. Freeze-drying is mainly used to extend the shelf lives of highly sensitive bio medicines.

The interests of both the pharma industry and patients alike are rather obvious. Everyone is seeking to provide their valuable and costly medications with the highest possible protection and ensure that they remain effective for as long as possible.

The advantages of SCHOTT PI Coating may be summarised as follows—a layer with attributes of reducing ion leaching, and better properties in freeze-drying. Furthermore the coating technique is highly flexible. It is possible to design the coated layers according to customers needs and for all pharma packaging formats like vials, syringes, and cartridges. And the coating is not only possible for glass containers, but also for polymers like COC, PET and PP.

(The author is Product Manager, Vials & Coatings, SCHOTT forma vitrum AG, Switzerland. She can be contacted on claudia.dietrich@schott.com)