Is it really necessary to conduct research with animals?

When we're sick, the doctor prescribes a pill, but we rarely think about how that drug got to us. The process begins with scientists studying a library of chemical compounds to choose the most suitable one to solve the problem while causing minimal side effects. To achieve this, they conduct an initial experiment on cells growing in a culture dish, then on animals, and finally on humans. This is the protocol that has been used for decades and has allowed us to have pharmacies full of solutions for almost every disease. But there have always been critical voices questioning whether animal experimentation was truly necessary. The reasons are primarily ethical, related to the unnecessary suffering of beings capable of feeling pain. Lately, this viewpoint has gained influence, and some countries have begun to take steps to eliminate these studies altogether.

Looking for shortcuts

The path from the first trial to the commercialization of a new drug takes between ten and fifteen years on average, and often costs more than €2 billion. Of every 10,000 compounds that begin research, only one or two manage to reach the end of the race and become medicines. Naturally, everyone wants to optimize the production chain, from pharmaceutical companies, which could get a better return on their investments, to patients, who can access therapeutic options sooner. But it's not so easy to find a place to cut costs.

It's difficult to shorten the final stage, the clinical trials. Tests must be carried out first with a few volunteers, gradually increasing their number to determine the safety and then the efficacy of the potential drug. As we saw with the COVID vaccines, with enough money and resources, progress can be made very quickly, but these conditions are rarely met. Lately, countries like the United States have implemented "shortcuts" to approve drugs more quickly, without the need for so many human trials. This increases the risk that some undesirable side effects may go undetected, but, in turn, it means that the benefit of the new drug cannot be obtained as quickly.

At the other end of the chain, the use of artificial intelligence has greatly accelerated the initial phases, because algorithms can more easily predict which compounds should be effective, without wasting time conducting so many cell experiments. This revolution She was recognized in 2024 with the Nobel Prize in Chemistry by the creators of AlphaFold, Google's DeepMind program, which allows predicting protein structure, is an essential (and previously very slow) step in finding therapeutic targets. Cell studies are important for understanding the mechanism of action of the substance being studied, but sometimes only the minimum necessary is performed to ensure the effect is as expected, and the process moves on to the next phase while further research continues in the background. The idea is that if the compound works, we'll figure out why later. But you can't start giving a compound to humans without first knowing that it won't be toxic. Cell studies can only give us part of the answer because they don't reproduce the complexity of a living being, which is made up of different organs and systems that interact with each other. You need to have an idea of ​​what will happen when the liver metabolizes the substance, how it will be distributed throughout the body, how long it will remain, how it will be eliminated... The positive and negative effects of the drug depend on all of this, and it's essential to understand it well to avoid surprises. And that's where animal experimentation comes in. But is it really that necessary?

Take animals out of the equation

They have been looking for alternatives to animal testing for some time, both because of social opposition, as well as logistical and ethical problems and the high cost of these experiments. One option is organoids, Miniaturized and simplified versions of our organs. Starting with stem cells, scientists have managed to create mini-livers, kidneys, and even brains that react to drugs in a way very similar to the originals. When they can be combined, they could function as a scaled-down version of a human body.

Organoids are not without ethical dilemmas. One concern is that a brain organoid may even develop some kind of consciousness. The patterns of electrical activity that spontaneously form in these structures are reminiscent of neurons in a real brain, to the point that scientists are wondering if they can acquire sufficient complexity to generate some kind of "thought."

A less complex variant would be Organs-on-a-chip, which combine biological components and physical substratesIn a small space (the chip), a series of elements are placed that replicate the function of an organ in a very simple way. For example, condensed versions of livers, hearts, lungs, and kidneys have been built. Although they cannot reproduce the great complexity of a human organ, they allow researchers to study how their functions change in response to drugs.

Artificial intelligence He has also entered the arena of substitutes, among other things by promoting the "digital twins"The idea is to use the power of AI to create a virtual organ (or even an entire body) that responds in the same way as the original and updates in real time. This way, everyone could have a digital twin that simulates their response to any treatment on a computer. For this idea to work, it is necessary that software Having all the necessary parameters to calculate tissue behavior is difficult, given the complexity of any biological system. For the results to be reliable, the system will need to be fed with large amounts of data, which we don't yet have. At the moment, the preliminary results are encouraging, but there is still work to be done.

We are in a hurry

While these potential substitutes are being developed, the United Kingdom announced late last year its plans to phase out all animal research, following the lead of the United States, which weeks earlier had announced similar cuts at several national research centers. The British are particularly sensitive to the issue of animal suffering, and their country already has some of the strictest regulations for this type of research. Every animal used must be thoroughly justified, and no intervention can be applied to them without prior approval from a government committee. Even so, activist protests occur periodically, forcing many universities and research centers to be as discreet as possible on these matters.

Although most researchers agree on the need to end the use of animals, these recent movements seem to stem more from political pressure and are not always supported by scientific reasoning. Research on specific animals has long since been reduced to a few exceptions. For example, experiments on pets, such as cats and dogs, are very rare, even though dogs were one of the most widely used models in 20th-century classical physiology. Social resistance to this idea has forced researchers to question whether it was truly necessary. The same applies to monkeys, which are evolutionarily too closely related to humans, and to... a brain that has responses similar to ours

Last November, the CDC (Centers for Disease Control and Prevention, the US scientific agency that studies infectious diseases) announced that they had been asked to stop using monkeys altogether by the end of 2026. Although this seems like good news at first glance, there are infections that cannot be studied in any other animal. This is the case with AIDS, a disease that The Trump administration has made it clear that it is not a priority. Nobody knows how this search will be conducted from now on.

The decisions of the United Kingdom and the United States, regardless of their motivations, are a step in the right direction: toward the eventual end of animal research. Despite being regulated to minimize suffering, it raises a host of ethical dilemmas, both for the general public and for scientists. But the reality is that these experiments are currently necessary. It's clear that almost everyone would be happy if they were abolished, but there is still no alternative that has proven to be able to fully replace them. Things will change over the next few years, undoubtedly, but in the meantime, starting to work on abolishing these experiments without a clear plan B would be putting the cart before the horse. Pursuing a noble goal, this could bring more problems than benefits.