Animal Testing: Flawed Science and the Case for Alternatives

Introduction

Animal models are faulty indicators and barriers in the development of drugs. Using animal models for human therapeutic experiments is inappropriate, unethical, and unreliable. With new, faster, and more accurate testing methods available, it is high time that the cruel practice of vivisection is totally banned from pharmaceutical research.

Animal testing is a cruel, unethical practice conducted on a large scale in almost all countries of the world. Taylor et al. (2008) reported that each year more than 115 million animals are used as test subjects worldwide. Statistics further indicate that in the U.S. alone, more than 25 million animals — including mice, dogs, chimpanzees, and cats — are subjected to painful and invariably fatal tests every year (Student, 2008). Analyses of animal studies over the last several years have shown that animal testing is largely irrelevant for human subjects. For instance, more than 11,600 chemical substances have been proven to have anti-cancer properties in mice, while not even one of them has a similar effect in humans. Conversely, among the 32 drugs used in cancer treatment in humans, none prove to be effective in mice (DLRM). This gives a fair indication of the profound physiological differences between species and the inappropriateness of animal testing. Yet most countries routinely continue with animal testing purely to fulfill regulatory requirements. A brief overview and discussion of the relevant facts helps better understand this important issue.

Animal Testing: A Review of the Evidence

A recent comprehensive review of animal and corresponding human tests has clearly revealed vast differences in responses between animals and humans to particular drugs. This review, published in the journal Alternatives to Animal Testing and Experimentation (AATEX), analyzed 20 animal and human studies and reported only 2 cases where animal studies proved consistent with the human studies (Andrew Knight, 2007). Another recent British study compared treatment effects between animal models and human clinical trials for six different medical conditions. Out of these, only 2 animal studies had concordant results with human clinical trials; furthermore, 2 of the studies showed effects totally contradictory to those indicated by the animal studies (Pablo Perel et al., 2007). The validity of using animal models as an indicator for human outcomes therefore stands largely in question.

One striking example of the dangers of relying on animal models for drug testing is the case of Vioxx, manufactured by Merck Laboratories. More than 80 million people worldwide used this drug in the treatment of arthritis. However, the drug, which was found to have a "heart-protective effect" in mice, proved to carry a high risk of causing heart attacks in humans. As Dr. John J. Pippin, M.D., chief advisor to the FDA, stated: "The Vioxx animal testing debacle is not unique. Over the years, millions of patients have been exposed to harmful drugs, such as Rezulin and Baycol, that seemed safe in tests on mice, dogs, rats, monkeys, horses, and other animals" (PCRM).

Animal Testing as a Barrier to Drug Development

There is enough evidence to suggest that animal testing has in fact delayed the development of critical drugs. The delay in the manufacture of protease inhibitors — one of the main classes of drugs for HIV patients — is a case in point. In 1989, Merck, Sharpe, and Dohme (MSD) worked on a protease inhibitor drug, but negative results from animal testing discouraged their work from proceeding to the next stage of human testing. However, four years later the company resumed its research and manufactured the drug Crixivan (a protease inhibitor), this time choosing to skip the animal testing phase entirely. The results were remarkable among HIV patients. As Mr. Shapiro, the former vice president of MSD, stated: "Animal tests were neither needed, nor used, to explore the ability of protease inhibitors to block the growth of the AIDS virus… the target action was already well understood and could be evaluated before the clinical trials using computers, cell culture and biochemical assays" (Peter Tatchell).

It is thus clear that animal models provide unreliable and often contradictory results for pharmaceutical research and also delay the development of vital drugs that could potentially save millions of human lives.

Conclusion

Europe is at the forefront of banning animal testing, and the European Centre for the Validation of Alternative Methods (ECVAM) has already approved several alternative tests, including the Agarose Diffusion Method — a standardized test for measuring the toxicity of synthetic chemicals — the Corrositex test, and the Transcutaneous Electrical Resistance Assay for analyzing skin corrosivity, as well as the AMES test for studying carcinogenicity (Animal Liberation Inc.). One of the new European standards is a pyrogenic test to replace the costly Limulus Amebocyte Lysate (LAL) assay and rabbit tests. According to Dr. Thomas Hartung, PhD, head of ECVAM, this new alternative testing method would "eliminate the need for 200,000 rabbits a year that were used to test biological compounds" (Gunjan Sinha, 2006).

There is sufficient evidence that clearly demonstrates vivisection must be abolished. Recent comparative studies have revealed the inappropriateness of using animal models for human therapeutic experiments. Animal models have been faulty indicators and have caused considerable delay in the development of long-awaited drugs to combat HIV. They have also proved dangerous and produced contradictory results in the research for anti-cancer drugs. The rapid development of toxicogenomics has opened the door to alternative, cheaper, and more accurate toxicology studies. It is time to replace cruel animal testing with in vitro testing methods. There is no question that the inhumane, morally repugnant, and scientifically unreliable practice of animal testing should be totally banned.