Glass Delamination Analysis of Drug Vials

Glass Delamination Analysis
of Drug Vials

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Glass delamination is defined as thin glass flakes shedding from the internal diameter of glass containers and vials. The flakes, also called “glass lamellae,” can be shed and suspended in parenteral drug products. Glass delamination is a huge concern within the pharmecutical industry due to high-profile product recalls. The quest for a solution starts with the manufacturing process for glass vials.

What causes glass to delaminate is unclear, but there are many possible contributing factors. Various factors that contribute to glass delamination include product composition, glass composition, glass forming temperature, and surface treatment. Due to the high temperatures used in forming tubular vials, the glass chemistry at the shoulder and heel is weakened. The focus of analysis is typically at the heel where a higher interaction occurs between the product and the glass surface. This in-house study compared different methods in imaging a delaminated glass surface.

Scanning electron microscopy (SEM), light microscopy and differential interference constrast (DIC) microscopy are techniques commonly used to analyze the glass surface for evidence of glass delamination. This study included two additional techniques: laser scanning confocal microscopy and scanning white light interference microscopy (SWLIM).

The scanning electron microscope uses an electron beam to generate secondary electrons from the sample to produce a high resolution image. The laser scanning confocal microscope system uses two light sources (a laser source and a white light source) to collect laser intensity, color, and surface data while producing a fully-focused image. The scanning white light interference microscope optical profiling system uses a dual-LED illumination source to acquire surface roughness measurements at the nanometer scale.

In this in-house study, we examined glass surfaces of drug product vials by three different analytical techniques – SEM, scanning laser and SWLIM – to illustrate and evaluate the interior glass surface defects as a result of delamination.

Figure 1: This image, taken by a laser scanning confocal microscope, shows the glass interior of a control sample. No glass delamination was detected.
Figure 1: This image, taken by a laser scanning confocal microscope, shows the glass interior of a control sample. No glass delamination was detected.
Figure 2: This is an image, taken by a scanning electron microscope, of a glass vial interior showing a delaminated inner surface
Figure 2: This is an image, taken by a scanning electron microscope, of a glass vial interior showing a delaminated inner surface.
Figure 3: This is an image, taken by a laser scanning confocal microscope, of the same area imaged by the SEM (Figure 2). This image shows better contrast and surface topography compared to the SEM image.
Figure 3: This is an image, taken by a laser scanning confocal microscope, of the same area imaged by the SEM (Figure 2). This image shows better contrast and surface topography compared to the SEM image.

surface profile of glass delamination interior

Figure 4: This is an image, taken using a SWLIM, of the same area as in the previous image. This image illustrates the glass delamination and shows a 3D surface roughness profile of the delaminated glass interior surface.
Figure 4: This is an image, taken using a SWLIM, of the same area as in the previous image. This image illustrates the glass delamination and shows a 3D surface roughness profile of the delaminated glass interior surface.
Figure 5: This image, taken with a laser scanning confocal microscope, shows a large area scan of a glass interior surface where major delamination has occurred.
Figure 5: This image, taken with a laser scanning confocal microscope, shows a large area scan of a glass interior surface where major delamination has occurred.

There are different advantages to using each of the three techniques for glass delamination analysis. SEM can give high magnification images of glass surfaces along with elemental data. Laser scanning confocal microscopy can provide high resolution imaging of the glass surface along with limited surface depth profile. The SWLIM provides a high resolution surface profile of the delaminated glass surface, but it cannot provide a confocal laser image. Each of the three techniques has its pros and cons. Depending on the objective of the analysis, each technique can be extremely useful for analyzing glass delamination surfaces.

Glass delamination analysis services that MVA Scientific Consultants offers:
• Glass delamination analysis
• Validation and testing of product vials
• USP testing support

MVA Scientific Consultants is a full-service analytical microscopy laboratory specializing in method development, problem solving and pharmaceutical investigative analysis. We have been in business for 26 years, and our experienced project leaders are personable, responsive and timely in delivering results.

More info on the techniques used in this study:
Glass Delamination Analysis Services Lab
SEM Analysis Services
SWLIM Analysis Services