When needles are re-used, it is often done to reduce the loss of valuable material to dead space or to reduce the time needed to change needles between injections. Most needles used in animal studies are designed and sold as single-use disposable needles. The system enables high accuracy and precision injection leading to minimal waste of injectate.
Through this Challenge, the team at Active Need Technology Ltd have developed a Precision Injection System to improve preclinical injections of rodents. A small refinement in how substances are delivered would positively impact a high number of animals. Approximately 58% were mice and many of these would have been involved in procedures involving an injection for example, for basic research programmes, administration of materials in efficacy, toxicity and pharmacokinetic studies, or in vaccine batch testing for quality and safety. In 2017, 1.89 million animals were used in experimental procedures in the UK. Use of needles more than once can also affect the quality of the scientific data collected as each animal in the cage is treated differently with respect to the process of injection. Infection and disease transmission can lead to study failure and result in further animal use and welfare concerns as well as loss of time and money. The transfer of material between animals (blood/tissue) can also increase the risk of infection and cross-contamination between cages of mice may occur. There is evidence to show that the single use of a needle can cause significant dulling/deformity of the needle tip 1, and that re-use of these needles may cause transient pain 3,4 and tissue damage at the site of injection. cells).Īll currently available products require significant time to manually change a needle between each animal. However, these are supplied with the needle attached making them inappropriate for use with substances that cannot be drawn up through the needle (e.g. Insulin syringes have been developed that have no dead space. However, they are not available in all needle gauges, and the syringe barrels are often difficult to read for small volumes which can affect the accuracy of small volumes draws. It is possible to purchase low dead space needles and syringes. For example, changing the needle for each animal in a study where the formulation stability requires all animals to be dosed within an hour of formulation preparation would require additional staff to complete the injections within the necessary timeframe. This can be a concern for studies where materials may need to be injected within a limited time into large numbers of animals. The time needed to change needles between injections.For certain cell lines, these can be difficult to grow and harvest in large quantities without affecting their quality. To account for dead space losses during administration, an excess of cells is needed. An increasing number of studies involve the injection of living cells for example, for xenograft models used in oncology research. This, combined with the size of mice and the small volumes administered, mean dead space losses can form a significant percentage of the material needed. The materials used in pilot studies are often difficult and expensive to synthesise and are therefore made in small quantities. The primary reason for re-use of needles and syringes is loss of valuable material (such as cells, compounds, viruses) in the fluid not expelled due to dead space between the syringe and the needle hub. When needles are re-used in mouse studies, it is most often to address the following: These concerns create confounding and unnecessary variables which can impact the quality of scientific data collected. Re-use also risks dulling of the needle, potentially increasing the pain and discomfort associated with subsequent injections. The re-use of needles results in a loss of sterility and can increase the risk of infection and disease transmission between individual animals and between cages. Two blogs published on the NC3Rs website have focused on the topic of re-using hypodermic needles in day-to-day practice and highlight the associated scientific and welfare concerns 1,2. Where needles are re-used, it is commonly done to reduce time and cost because of the involvement of large numbers of mice and/or test material. Most needles used to administer material parenterally in animals are designed and sold as single-use disposable needles. via intravenous, subcutaneous, intraperitoneal or intramuscular routes) or for collecting blood samples. Hypodermic needles are used throughout medical research involving animals for injecting substances (e.g.
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