Some people gives positive responses while asking about whether it is just to use animals for trials of medicines meant for human consumption, while others oppose because they think it is animal cruelty.
It is not right to use animals for trials of human medicines as they may feel uncomfortable or even die as the medicines are about trial and error basis. But, whether the medicines will have a negative impact upon consumtion needed to be tested before injecting inside human body just to make sure it does not have any side affects makes a valid point to use animals as guinea pigs.
The increasing number of evolving diseases needs to be researched and prevented from hurting mankind. Due to the fast evolution process of diseases, it is necessary to research and find ways to prevent diseases to infect human body and also be cured when the germs enter inside human body. The process of creating cure to a disease involves creation of complex substances in laboratories which are used to experimented to see whether they prevent the evolution of the viruses. After being successful to see that the cure actually works, the next step is to observe to inject the cure inside a vector who is already infected with the virus causing the disease. As the cures are made using trials, it may have detrimental effects on human body upon injection. So, it is necessary to make sure no side effects may occur while being injected with the cure. Animal trials give us an idea about the experience human body might capture while being injected. So, it gives us a way of observing the vitals while the cure is working inside the animal body.
As animals are innocent and they cannot give consent for acting as trials, it is some kind of animal cruelty for putting them at stake of being unhealthy or even losing their lives. The side effects of the medicine might damage them permanently. Also, that particular animal might even give birth to another form of disease as a side effect of the experiment.
In conclusion, although animals might be affected permanently due to being used as trials for cures of diseases, it is necessary to use them as so because the mankind might be saved from being extinct.