From 24 Standards to Online Inspection: A Full View of Pharma Glass Quality Control

Industry standards are the backbone of any healthy sector, and the old adage that nothing can be built without rules applies just as strongly to packaging. As the packaging industry scales up, clear standards become even more essential to keep that growth on track. This article rounds up the standards governing the glass segment of pharmaceutical packaging.

China currently maintains 24 medicinal glass standards: 19 national and 5 industry standards, broken down into 9 product standards plus 15 test method and related standards. A recurring weakness across the current set is standard age - most were drawn up in the 1980s or 1990s and have fallen well behind industry and product developments. Adoption levels are also weak, with non-equivalent adoption dominating. After WTO entry, aligning the medicinal glass sector and its products with international practice has required standards reform to lead the way.

Product standards illustrate the problem. Of the nine in force, market shifts have fundamentally reshaped the structure and uses of medicinal glass bottles, leaving several varieties in shrinking demand and their standards out of step. Large-format and wide-mouth bottles for tablets, for instance, have largely given way to plastic bottles and aluminium foil, while oral liquid preparations for health-care and nutritional drugs now dominate and are trending toward greater variety and smaller formats. Threaded tubular glass bottles, used mainly for tablets and powders, are also seeing volumes decline as plastic and foil alternatives take over.

Among product standards, Medicinal Glass Bottles ranks as one of the oldest and no longer matches market demand or the current product landscape. The National Medical Products Administration has therefore placed it on the list for restriction and revision. To serve the pharmaceutical industry's evolution and demand for biomedical and biological preparations, the not-yet-published 2000 edition of the pharmaceutical industry standards will reference relevant international standards.

Testing medicinal glass

Depending on end use, testing of medicinal glass falls into three broad groups: physicochemical performance, specifications and dimensions, and appearance quality. Once aligned with international medicinal glass standards and test methods, testing must also extend to glass chemical composition and the leaching levels of harmful substances.

Physicochemical performance is a key quality indicator for medicinal glass and a window into a product's intrinsic quality, with a direct bearing on drug quality. Items in this category cover water resistance, internal stress, internal pressure resistance, thermal shock resistance, freezing resistance, breaking force, and acid and alkali resistance.

Water resistance: this is the chemical stability of medicinal glass. Because the container contacts the drug directly, it must not cause deterioration or loss of efficacy through chemical change during shelf life, so chemical stability has a direct impact on drug quality.

Water resistance is tested by the grain method or the container method; both work by neutralising material released on or within the glass surface with a measured amount of acid solution. The grain method assesses the chemical performance of the glass material, per GB12416.2-1990 (hydrolytic resistance of glass grains at 121°C - test and classification) and GB/T6582 (glass grains at 98°C). The container method assesses the inner surface, per GB12416.1-1990 (hydrolytic resistance of medicinal glass containers - test method and classification) and GB/T4548-1995 (hydrolytic resistance of the interior surfaces of glass containers - test method and classification).

A draft national standard has also been prepared for international alignment: determination and classification of the hydrolytic resistance of glass products and glass containers by flame spectrometry. It enables quantitative measurement of the substances released from glass surfaces by water attack and of the amounts involved.

Internal stress: this reflects the annealing quality, or annealing characteristics, of the glass. Containers with poor annealing are prone to breakage or shattering in use, which compromises drug containment and medication safety. GB12415-1990 (inspection method for internal stress in medicinal glass containers) is the usual standard; it determines stress via optical path differences at different wavelengths, typically using an LRR-8 digital quantitative stress meter.

Internal pressure resistance: internal pressure measures the overall strength of a glass container; internal structure, uneven wall thickness and surface appearance defects all affect that strength. GB/T4546-1998 (test methods for internal pressure resistance of glass bottles and jars) applies, with the TYJ-B linear pressurisation internal pressure tester as the common instrument.

Thermal shock resistance: this gauges a container's ability to withstand temperature change, usually expressed as a tolerable temperature differential. The standard is GB4547-1991 (test methods for thermal shock resistance and thermal shock endurance of glass containers), using a digital automatic temperature-controlled thermal shock tester.

Freezing resistance: a low-temperature performance check used mainly for glass bottles destined for lyophilised preparations; the test equipment is a freezer at -43°C or below.

Breaking force: this tests the snap-off behaviour of ampoules and is a key indicator of ampoule usability. The ZLY-2000 digital breaking force meter is the instrument of choice.

Acid and alkali resistance: a measure of chemical stability. Methods include GB6582-1986 (determination of hydrochloric acid resistance at 100°C by flame emission or atomic absorption spectrometry), GB/T15728-1995 (resistance to boiling hydrochloric acid - gravimetric test method and classification) and GB/T6580-1997 (resistance to mixed aqueous solutions - test method and classification). Core equipment includes flame photometers, atomic absorption spectrometers and standard laboratory instruments.

Dimensions reflect the forming process quality of medicinal glass. Consistent, stable dimensions underpin pharmaceutical packaging production and strongly influence filling, sealing, storage and use.

Geometric dimensions: digital electronic callipers, vernier callipers or height gauges are typically used for bottle mouth and body measurements.

Wall, bottom and mouth thickness: common instruments include digital electronic bottle bottom and wall thickness gauges, and digital electronic bottle mouth edge thickness gauges.

Vertical axis deviation: a perpendicularity check, governed by GB8452-1987 (glass containers - test method for vertical axis deviation of glass bottles) and measured with a ZPY-10 digital axis deviation gauge.

Straightness: a measure of how far a glass tube bends, commonly tested with an LSR-1000 digital glass tube straightness meter.

Weight and capacity: weighing and titration methods are used to determine bottle weight and volume.

Appearance quality: this covers surface defects such as stones, bubbles, striae, bubble lines, cracks and seams, normally assessed visually or with a graduated magnifier.

Chemical composition and harmful substance content

Testing chemical composition and harmful substance content is central to raising quality levels in medicinal glass containers and to international alignment.

The forthcoming pharmaceutical industry standard, Classification of medicinal glass compositions and their test methods, adopts ISO12775-1997 (classification by composition and test methods for normally mass-produced glass) on a non-equivalent basis, and sets out clear classifications and requirements for the composition, material properties, performance and application scope of each medicinal glass type.

As2O3 and Sb2O3 are often introduced into medicinal glass batches as fining agents, and standards already set limits on their release. China is currently drafting related control and testing standards to cap harmful elements on safety and hygiene grounds.

Online automatic inspection of medicinal glass containers

Online automatic inspection places automated units at the cold end of the glass line, checking every bottle's dimensions and appearance against preset criteria and rejecting defective items.

The approach is already standard practice internationally, yet domestic production still relies largely on manual visual inspection - labour-intensive and prone to missed defects, which contributes to the uneven quality of domestic medicinal glass containers. Accelerating the introduction, digestion, absorption and installation of online automatic inspection equipment will be the direction of travel and an effective route for the sector to reach international levels and lift product quality.

Source: China Packaging Network (pack.cn), original link: http://news.pack.cn/show-361840.html