Plastic container interaction

Admixture incompatibility- Do not mix or dilute with other solutions or drugs in syringe or infusion flask. Diazepam interacts with plastic containers and administration sets, significantly decreasing availability of drug delivered. 

The surface of the sample container may interact with the analyte. The surfaces can provide catalysts (e.g., metals) for reactions or just sites for irreversible adsorption. For example, metals can adsorb irreversibly on glass surfaces, so plastic containers are chosen for holding water samples to be analyzed for their metal content. These samples are also acidified with HNO3 to help keep the metal ions in solution. Organic molecules may also interact with polymeric container materials. Plasticizers such as phthalate esters can diffuse from the plastic into the sample, and the plastic can serve as a sorbent (or a membrane) for the organic molecules. Consequently, glass containers are suitable for organic analytes. Bottle caps should have Teflon liners to preclude contamination from the plastic caps. 

The second category is that of the mass transfer of heavier organic vapours and liquids as occurs in polymeric constructions such as plastic containers and bottles. In this case the situation is more complicated very often there is stronger interaction between penetrant and polymer. The performance of useful and repeatable experiments and the acquiring of quantitative knowledge can be very difficult. 

The packaging material must not interact with the product either to adsorb substances from the product or to leach chemicals into the product. Plastics contain additives to enhance polymer performance. PVC may contain phthalate diester plasticizer, which can leach into infusion fluids from packaging. Antimicrobial preservatives such as phenylmercuric acetate are known to partition into rubbers and plastics during storage, thus reducing the formulation concentration below effective antimicrobial levels. 

Interactions with Closure Systems. Elastomeric and plastic container and closure systems release leachable compounds into the liquid dosage form, such as nitrosamines, monomers, plasticizers, accelerators, antioxidants, and vulcanizing agents [44], Each type of container and closure with different composition and/or design proposed for marketing the drug or physician s samples has to be tested and stability data should be developed. Containers should be stored upright, on their side, and inverted in order to determine if container-closure interactions affect product stability [6,45]. 

This paper presents the combined experimental/numerical investigation of the behaviour of fluid-filled plastic containers subjected to drop impact. Drop Impact experiments were conducted on original and modified bottles. During the test, strain and pressure histories were recorded at various positions. Tests were simulated numerically using the two-system FSI model. Both solid and fluid domains remain fixed during the calculations, i.e. a small-strain analysis was performed for the solid while an Eulerian fi-ame of reference was used for the fluid. This procedure was found to be simple, stable and efficient. Numerical results agreed well with experimental data, demonstrating the capability of the code to cope with this complex fluid-structure interaction problem. 

For drug preparations that will be used for internal or mucous membrane administration (i.e., parenteral preparations, ophthalmics, creams and salves, etc.), additional testing must be performed to assure that any leachants will not cause biological reactions that may be detrimental to the patient. To do this, a test protocol has been established that screens materials used in containers to test for biological interactions. This protocol should be applied to any plastic container closure systems regardless of the type of container that will directly contact pharmacopeial preparations in storage before they are invasively used. This includes all closure systems for parenteral vials. ... 

McCarthy TJ. Interaction between aqueous preservative solutions and their plastic containers III. Pharm Weekbl 1972 107 1-7. 

Kakemi K, Sezaki H, Arakawa E, et al. Interactions of parabens and other pharmaceutical adjuvants with plastic containers. Chem Pharm Bull 1971 19 2523-2529. 

Rock and co-workers (1988) reported the interaction of diethylhexyl phthalate with blood during storage in PVC plastic containers. The plasticizer is leached into the plasma and converted to mono(2-ethyIhexyl) phthalate by a plasma enzyme. At a level of >125 mg/mL in the blood mono(2-ethyl-hexyl) phthalate produced a 50% decrease in heart rate and blood pressure in rats. 

Plastic containing Cl is in its essence a composite material. Inhibitors and special additives, which also have a function regulating physical-chemical interactions between the polymer and inhibitor, are spread within the polymer component of the composite at a given degree of cohesion with the polymer. Compatibility of the Cl with the polymer binder should not be too high as the inhibitor would not be released from the composite. In the case of low compatibility the release rate of the inhibitor will be too high and the life of the plastic as an inhibitor carrier would be unacceptably low. 

The effect of water on Tg has also been estimated from a mixture theory [292] using expressions that had been derived for plasticizer-containing polymers [295]. It has, however, been shown that water in nylon does not behave as just a simple plasticizer [296] a finding that supports a more complex interaction of water with polyamides such as shown in Figure 2.29 [293]. 

The mle like dissolves like is only partially useful because it is not valid for polar polymers. Polar polymers are compatible only with some polar plasticizers. Interaction of polar polymers and plasticizers depends on the presence and arrangement of groups capable of donor-acceptor interactions. Polar plasticizers with a proton-acceptor character (esters, ethers, and nitriles) are most useful for polymers having average polarity (e.g., PVC, PC, and butadiene-aciylonitrile copolymers). For other polar polymers, especially those soluble in water, plasticizers containing OH-groups are more effective. 

In the case of plasticized poly(butyral-co-vinyl alcohol) [73], use of dipolar rotational spin-echo CNMR in conjunction with C) determinations, has shown that the frequencies but not the amplitudes of cooperative main-chain motions of the polymer in the hard regions, corresponding to solid polymer associated with partially immobilized plasticizer, are influenced by interactions with the soft regions attributed to liquid plasticizer containing mobile polymer. From this result, a schematic representation of the partitioning of the polymer and plasticizer in terms of a two-phase domain model has been proposed. 

Being relatively smaller in molecular size, these additives can migrate from the plastic body to the environment if they are not totally bound in the plastic material. They may eventually migrate into food products packed in plastic containers, or they may interact with humans in other ways. 

To ensure that no chemical or physical interaction occurs which might cause leakage, the material, from which the containers are made, needs to be compatible with the properties of the liquid. In addition, containers may need protection against corrosion, e.g. by painting, and plastic containers can often suffer degradation by natural light, which can be reduced by suitable shading of the container. 

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