Containers for Parenteral Preparation: Containers are in close contact with the product. Both the chemical and physical characteristics affect the stability of the product, but the physical characteristics are given primary consideration in the selection of a protective container.
Glass containers traditionally have been used for sterile products, many of which are closed with rubber stoppers. Interest in plastic containers for parenteral is increasing, and such containers are being used for commercial ophthalmic preparations and IV solutions.
The principal ingredient of the various plastic materials used for containers is a thermoplastic polymer.
Although most of the plastic materials used in the medical field have a relatively low amount of added ingredients, some contain a substantial amount of plasticizers, fillers, antistatic agents, antioxidants, and other ingredients added for special purposes.
These ingredients are not usually chemically bound therefore, may migrate out of the plastic and into the product under the conditions of production and storage.
Plastic containers are used mainly because:
- Light in weight
- When low in additives have low toxicity and low reactivity with products.
Tissue toxicity can occur from certain polymers, but additives are a more common cause.
Reactivity due to sorption (absorption and/or adsorption) has been found to occur most frequently with the polyamide polymers, but additives leached from any of the plastic materials may interact with the ingredients of the product.
Most polymers are adversely affected by the elevated temperatures required for thermal sterilization and have a relatively high permeability for water vapor.
Significant permeation of gases including oxygen may occur with some materials. Ex: polystyrene
It is the most widely used.
It is a linear polymer that can be produced to be highly crystalline. Because of its crystallinity, it has high tensile strength, a high m.p. of 165°C, and relatively low permeability to gases and water vapors.
It is translucent, abrasion-resistant, and has high surface gloss.
Withstands normal autoclaving temperatures.
Flexible polyethylene containers are used for ophthalmic solutions to be administered in drops and flexible polyvinyl chloride bags for IV solutions.
The newer group of polymers, the polyolefins has made possible the development of bottles that are rigid enough to hold their shape during processing but can collapse under atmospheric pressure as an outflow of a solution occurs during IV administration to the patient.
USP Procedure for Evaluating the Toxicity of Plastic Materials:
1. Implanting small pieces of plastic materials intramuscularly in rabbits
2. Injecting eluates using sodium chloride injection with an without alcohol intravenously in mice and injecting eluates using PEG400 and sesame oil intraperitoneally in mice
3. Injecting all four eluates subcutaneously in rabbits. The reaction from the test samples must not be significantly greater than non-reactive control samples.
It is the preferred material for injectable products.
Is composed principally of silicon dioxide tetrahedron, modified physicochemically by such oxides as those of sodium, potassium, calcium, magnesium, aluminum, boron, and iron.
The two types of glass commonly used are soda-lime and borosilicate glass.
The USP provides the powdered glass and the water attack test for evaluating the chemical resistance of glass.
The test results are the measurement of the number of alkaline constituents leached from the glass by purified water controlled elevated temperature conditions.
Similarly, powdered glass test is performed on the ground, sized glass particles and water attack test is performed on whole containers.
Water attack test is used only with containers that have been exposed to sulfur dioxide fumes under controlled humidity conditions.
Based on results from the official test glass are classified as:
- Type I
- Type II
- Type III
- NP (Non-parenteral)
- Type I is preferred most for sterile products.
- Type II and III may be used when the product has a non-aqueous vehicle or the period of contact with the aqueous vehicle is brief, as with dry powders reconstituted just before use/ if the non reactivity between the glass and product has been established.
Containers use considerations:
1. Rubber closures
2. Composition and reactivity
3. Physical characteristics
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