LAUSR

Background Animals have been used for the testing of new drugs and nanoparticles to determine their safety and effectiveness before application in humans. Numerous drugs and nanoparticles have been developed through animal tests, and development in medical nanotechnology is progressing rapidly. However, a good experiment requires many animals. The primary measures to reduce animal experiments include reducing the number of animals used in each experiment and replacing laboratory animals with inanimate, cellular, or inferior animals to reduce sacrifices. Area covered Developing nanoparticles using simulations rather than experiments may be another alternative. Instead of animals, human cells or animal-derived organs, tissues, or cells could be used in experiments. These methods allow rapid toxicity and efficacy testing at low cost. However, the disadvantage of these methods is that they cannot accurately replicate the complex interrelationships between human organs, biological reactions to specific routes of administration, or toxicity of substances resulting from metabolic processes. To overcome these shortcomings of in vitro tests, new technologies such as organoids and organ-on-chips are progressing. These can be used to quickly examine the efficacy of newly developed drugs and nanoparticles and can be useful in developing patient-tailored agents. Expert opinion These technologies offer some promise but it is still difficult to entirely replace animal experiments. However, the scope of methods to replace experimental animals is widening, suggesting the potential to refine, reduce, and ultimately replace animal testing.