Are There Adequate Alternatives to Animal Testing?
August 19, 2015 | by Sarah Massey
Animal testing has played an integral role in the scientific method for thousands of years. Today, animals are still widely used for research purposes and the use of animal models during preclinical trials is an important step in the path to drug development. However, with the cost of developing a pharmaceutical product estimated at $2.6 billion – a figure that has more than doubled since 2004 – drug companies are increasingly looking for new ways to save money.
The disadvantages of using animals in the drug development process, as well as the currently approved alternatives to animal testing are reviewed in the first section of this article. Over the next few pages, three promising in vitro and in silico technologies, Modular Immune in vitro Construct (MIMIC), Organ-on-a-Chip and Computer Models of Adverse Drug Reactions, which could reduce the need for animals in research, are reviewed in more detail.
Drawbacks of Animal Testing
Animal testing is required by the Food and Drug Administration (FDA) in the early stages of candidate drug analysis, in order to collect sufficient data on the drug’s safety and efficacy. Pharmacokinetic and Absorption/Distribution/Metabolism/Excretion (ADME) studies are generally done using two species to understand both the effects of the drug in a living system, as well as how the body processes the drug.
New compounds must also be classified according to their acute toxicity; the LD50 is the lethal dose required to kill 50% of test subjects. The data collected during LD50 experiments in animals can be extrapolated to determine how the drug might function in a human system, and will be an important factor in determining if the substance gets approval for human trials.
All federally-funded research facilities are required to follow strict animal welfare guidelines set by the Canadian Council on Animal Care in Science (CCAS), the Institutional Animal Care and Use Committee (IACUC) in the US, and a number of Animal Welfare Bodies (AWB) as part of the European Commission including the National Centre for the Replacement, Refinement & Reduction of Animals in Research (NC3RS) in the UK. Additionally, practitioners must abide by the 3 R’s of research involving the use of animals, wherever possible:
- Replacement of animals with alternative in vitro and in silico models.
- Reduction in the number of animals used in the study.
- Refinement in the experimental design to optimize animal welfare.
These guidelines can make experimental design using animals as test subjects more complicated and may ultimately influence the results of the study.
Though animal testing has come under fire in recent years due to ethical concerns regarding the use of intelligent animals as test subjects, there are a multitude of other downsides to the use of animals in research. Firstly, animal testing is costly compared to other methods; it’s estimated that the US government spends between $12 and $14.5 billion annually on animal experimentation.
In addition, research animals require a substantial input of time for feeding and general care, as well as a significant amount of space for housing. The most compelling argument against the use of animals in research, is that physiological responses of a drug tested in an animal will never be a true predictor of the response of a human. Despite similarities between humans and laboratory animals – it is believed that we are approximately 99% genetically identical to chimpanzees – animal trials may show very different results compared to human trials.
Alternatives to Animal Testing Already in Use
While animals are still widely used in medical research today, there are some traditionally animal-based methods that have been replaced by faster, less-expensive non-animal assays. Until 1960, the principal bioassay for confirming a woman’s pregnancy was to inject her urine into immature rabbits to induce ovulation. This test relied on the presence of human chorionic gonadotropin (hCG) in the sample to induce ovulation in the rabbit, and confirm pregnancy. However, the similarity of hCG to another hormone, luteinizing hormone (LH), often made it difficult to distinguish the two, and accurate quantification of hCG levels was near impossible.
Before the advent of cell culture, all new cosmetic and topical products were required to be tested on animals to determine the potential for skin irritation. In the past 20 years, companies have developed multilayered human epidermal cell culture models to replace the need for animal testing, and provide more accurate results for the irritation potential of a product on human skin. These models include EpiDerm™ by MatTec Corporation and Episkin developed by SkinEthic, both of which are approved for use in Canada and the European Union.
The following is a review of some animal testing alternatives that are aim to both reduce the cost of drug testing as well as limit the number of animals needed for preclinical trials.
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Keywords: Animal Testing, Preclinical Trials, ADME, Pharmacokinetics, Vaccine, Pharmaceutical
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