USP General Chapter 660 Containers – Glass | Types of Glass Containers Used In Pharmaceuticals | Glass Vial Testing as Per USP |
Glass containers for pharmaceutical use are intended to come into direct contact with pharmaceutical products. Glass used for pharmaceutical containers is either borosilicate (neutral) glass or soda-lime-silica glass. Borosilicate glass contains significant amounts of boric oxide, aluminum oxide, and alkali and/or alkaline earth oxides in the glass network. Borosilicate glass has a high hydrolytic resistance and a high thermal shock resistance due to the chemical composition of the glass itself; it is classified as Type I glass. Soda-lime-silica glass is a silica glass containing alkaline metal oxides, mainly sodium oxide, and alkaline earth oxides, mainly calcium oxide, in the glass network. Soda-lime-silica glass has a moderate hydrolytic resistance due to the chemical composition of the glass itself; it is classified as Type lll glass. Suitable treatment of the inner surface of Type lll soda-lime-silica glass containers will raise the hydrolytic resistance from a moderate to a high level, changing the classification of the glass to Type ll.
The following recommendations can be made as to the suitability of the glass type for containers for pharmaceutical products, based on the tests for hydrolytic resistance.
- Type I glass containers are suitable for most products for parenteral and nonparenteral uses.
- Type II glass containers are suitable for most acidic and neutral aqueous products for parenteral and non-parenteral uses.
- Type II glass containers may be used for alkaline parenteral products where stability data demonstrate their suitability.
- Type lll glass containers usually are not used for parenteral products or for powders for parenteral use, except where suitable stability test data indicate that Type lll glass is satisfactory.
The inner surface of glass containers may ae treated improve hydrolytic resistance. The outer surface of glass containers may be treated to reduce friction or for protection against abrasion or breakage. The outer surface treatment is such that it does not contaminate the inner surface of the container.
Glass may be coloured lo provide protection from light by the addition of small amount of metal oxides and is tested as described in Spectral Transmission for coloured Class Container. A clear and colourless container that’s made light resistant oy means of an opaque enclosure is exempt from the requirements for spectral transmission.
Specific Tests
The Glass Grains Test combined with the Surface Glass Test for hydrolytic resistance determines the glass type. The hydrolytic resistance is determined by the quantity of alkali released from the glass under the conditions specified. This quantity of alkali is extremely small in the case of the more resistant glasses, thus calling for particular attention to all details of the tests and the use of apparatus of high quality and precision. Conducting these tests in conjunction with a glass standard reference material (SRM) on a routine basis will help to ensure the accuracy of the method. Reference materials are available for both borosilicate glass (SRM 623) and soda-lime-silica glass (SUM 622) from the National Institute of Standards and Technology. The tests should be conducted in an area relatively free from fumes and excessive dust. Test selection is shown in Table 1 and Table 2.
Table 1. Determination of Glass Types
| Container Type | Test | Reason |
| l, ll, lll | Glass Grains Test | Distinguishes Type I borosilicate glass from Type ll and lll soda-lime-silica glass |
Table 2. Determination of Inner Surface Hydrolytic Resistance
| Container Type | Test | Reason |
| l, ll, lll | Surface Glass Test | Determines hydrolytic resistance of inner surface; distinguishes between Type l and Type ll containers with high hydrolytic resistance and Type lll containers with moderate hydrolytic resistance |
| l, ll | Surface Etching Test of comparison of Glass Grain Test and Surface Glass Test data | Where it is necessary, determine whether high hydrolytic resistance is due to inner surface treatment or to the chemical composition of the glass containers |
Glass containers must comply with their respective specifications for identity and surface hydrolytic resistance to be classified as Type I, II, or lll glass. Type I or Type ll containers for aqueous parenteral products are tested for extractable arsenic.
Hydrolytic Resistance :
Apparatus
Autoclave: For these tests, use an autoclave capable of maintaining a temperature of 121 ± 1°C, equipped with a thermometer, or a calibrated thermocouple device, allowing a temperature measurement independent of the autoclave system; a suitable recorder; a pressure gauge; a vent-cock; and a tray of sufficient capacity to accommodate the number of containers needed to carry out the test above the water level. Clean the autoclave and other apparatus thoroughly with Purified Water before use.
Mortar and pestle: Use a hardened-steel mortar and pestle, made according to the specifications in Figure I.
Other apparatus: Also required are a set of three square-mesh stainless steel sieves mounted on frames consisting of US sieve Nos. 25. 40, and 50. A mechanical sieve-shaker or a sieving machine that may be used to sieve the grains; a tempered, magnetic steel hammer; a permanent magnet; weighing bottles; stoppers; metal foil (e.g., aluminum, stainless steel); a hot air oven, capable of maintaining 140 ± 5°C; a balance, capable of weighing up to 500 g with an accuracy of 0.005 g; a desiccator; and an ultrasonic bath.
Reagents :
Carbon dioxide-free water: This is Purified Water that has been boiled vigorously for 5 min or more and allowed to cool while protected from absorption of carbon dioxide from the atmosphere, or Purified Water that has a resistivity of not less than 18 Mohm-cm.
Methyl red solution: Dissolve 50 mg of methyl red in 1.86 mL of 0.1 M sodium hydroxide and 50 mL of ethanol (96%), and dilute with Purified Water to 100 mL. To test for sensitivity, add 100 mL of carbon dioxide-free water and 0.05 mL of 0.02 M hydrochloric acid to 0.1 mL of the methyl red solution. The resulting solution should be red. NMT 0.1 mL of 0.02 M sodium hydroxide is required to change the color to yellow. A color change from red to yellow corresponds to a change in pH from pH 4.4 (red) to pH 6.0 (yellow).
Click below link for Test Procedures of Glass Container:
Glass Grains Test Procedure for Glass Container : Glass Grains Test – USP
Surface Glass Test Procedure for Glass Container : Surface Glass Test
Surface Etching Test Procedure for Glass Container : Surface Etching Test – USP
Arsenic Test for Glass Container : Arsenic Test For Glass Container – USP
Spectral Transmission for Coloured Glass Containers : Spectral Transmission for Colored Glass Containers
