To answer this question, it is first necessary to understand that the medications we use generally come from three basic sources. They are described below:

1. Biological Extracts

Medications produced from extracts, typically from plants, are among the earliest types of medicine used by humanity. A modern example is cannabidiol (CBD), extracted from hemp (Cannabis sativa). Another is vinblastine, used in cancer treatments and derived from the Madagascar periwinkle (Catharanthus roseus). Additionally, willow bark (Salix spp.) is a natural source of salicin, an anti-inflammatory compound that the human body converts into salicylic acid—a precursor to aspirin.

2. Chemical Synthesis

Aspirin (acetylsalicylic acid) is a prime example of a drug obtained through this method. While salicin was used as a medicine derived from willow bark, aspirin itself is produced via chemical synthesis. Salicylic acid is chemically manufactured through the Kolbe-Schmitt reaction, which treats sodium phenoxide with carbon dioxide ($CO_2$) under high pressure and temperature, followed by acidification. The resulting salicylic acid is then used to synthesize acetylsalicylic acid through acylation with acetic anhydride.

3. Biopharmaceuticals (Biologics)

Unlike synthetic chemicals, biopharmaceuticals are drugs produced from living organisms (such as cells, bacteria, and yeast) or biological materials (including proteins, RNAs, and enzymes) using advanced biotechnology. These are complex molecules—such as monoclonal antibodies, recombinant proteins, RNAs, and vaccines—used to treat chronic diseases, autoimmune disorders, and cancer by acting on specific targets within the body.

Biologics are derived from the genetic manipulation of organisms to enable the production of proteins of biomedical interest, such as insulin, growth hormones, antibodies, and growth factors produced in Escherichia coli bacteria or cultured mammalian cells. In these cases, the bacteria are genetically engineered to produce the biological product using a cloned human gene inserted into the cell. Beyond bacteria, scientists can also engineer insect cells, mammalian cells, plant cells, and even organisms such as cattle, sheep, fish, and plants.

The mRNA vaccines used to combat COVID-19 are biological products obtained through enzymatic synthesis. This process uses recombinant RNA polymerase enzymes (derived from E. coli) and a cloned DNA template to transcribe the mRNA. This mRNA is then encapsulated in lipid nanoparticles to create the final vaccine formulation.

When used correctly, all medications are safe and essential for people's health and quality of life. Drugs undergo rigorous testing before being approved and must be regulated by official health agencies. In Brazil, this role is expertly fulfilled by the National Health Surveillance Agency (Anvisa). Instituto Butantan is a global benchmark in the production of immunobiologicals and, through CeRDI, works to create even more advanced and efficient biopharmaceuticals, specifically focusing on monoclonal antibodies and influenza vaccines

Before being approved for public use, every medication—including vaccines and monoclonal antibodies—undergoes rigorous testing. The goal is to ensure they are not only effective in fighting disease but also safe. All medications can cause side effects and must be used with care. Nevertheless, testing usually demonstrates that the benefits outweigh any adverse effects, allowing the drug to be approved with specific guidelines and warnings regarding potential risks.

But how do these tests work? While animal testing and trials involving human volunteers (usually healthy individuals) are well-known, patients already facing a specific health condition often volunteer to participate in the development of new treatments. All these methods can be part of the same study, which is generally divided into two main types: non-clinical and clinical trials.

Non-clinical Trials

Essentially, these are tests that do not involve human subjects and typically represent the first phase of developing a new drug. Non-clinical trials have two goals: first, to verify if the active ingredient effectively hits the target causing the disease; and second, to identify if any substances in the medication could be toxic or cause adverse reactions over time. If a new substance fails this stage, there is no reason to proceed with human testing.

Animal testing is very common in non-clinical studies: mice are the most well-known subjects, but monkeys and even dogs can help researchers discover how a new drug behaves. However, there are other forms of non-clinical testing, such as in vitro studies (using cells or tissue samples grown in a laboratory) and computer modeling (using data-driven calculations and virtual simulations).

Clinical Trials

Once non-clinical trials yield promising results, clinical trials in humans may be approved. In this stage, the new substance is tested in different ways depending on the health issue being studied. Research usually begins with a small group of healthy volunteers to map risks and side effects. Next, patients with the disease are included to evaluate efficacy, although safety is continuously monitored throughout all clinical trials. Adults from high-risk groups may also be included later.

Often, the mere expectation of improvement from a new substance can make a patient feel better—this is known as the placebo effect. Researchers must ensure that the medication works beyond this psychological effect. This is why blind trials are common: patients are divided into two groups; one receives the experimental drug and the other receives a placebo, but no patient knows which group they are in. There are also double-blind trials, where neither the patients nor the doctors administering the substance know who is receiving the real medication and who is receiving the placebo. This ensures that researchers interpret the data without being influenced by their own desire for the drug to succeed. The approval process for a new medication involves three primary clinical phases. Phase 1: Conducted with a small group (10–20 individuals) to primarily evaluate safety; Phase 2: Conducted with a larger group (100–200 individuals) to assess efficacy while continuing safety evaluations; Phase 3: Conducted with thousands of individuals to primarily evaluate efficacy on a large scale, while safety remains under constant monitoring.

After Phase 3 approval, the medication can be registered and produced. There is also Phase 4, consisting of post-marketing clinical trials where efficacy and safety are monitored while the product is already commercially available. Throughout all these stages, Pharmacovigilance tracks all short- and long-term adverse effects as well as ongoing effectiveness. Even after approval and distribution, medications continue to be studied long-term. Understanding and valuing every stage of this life-saving research is essential. The Center for Research and Development in Immunobiologicals (CeRDI) conducts clinical trials to ensure the efficacy and safety of the innovative influenza vaccines and monoclonal antibodies developed by Instituto Butantan, enabling their registration, manufacturing, and use by the population.

To understand these diseases, we must first review how the immune system functions. Leukocytes are cells that circulate in the blood and work to defend the body. Also known as white blood cells, there are five main types: neutrophils, monocytes, eosinophils, basophils, and lymphocytes. With the exception of lymphocytes, these cell types participate in the innate immune response, which represents the body's first line of non-specific defense. Lymphocytes, on the other hand, are divided into two primary types: T lymphocytes (T cells) and B lymphocytes (B cells). These two types participate in the adaptive immune response. B cells specialize in recognizing and fighting invaders by producing antibodies—either secreted into the bloodstream or bound to the cell membrane—while T cells are responsible for the cell-mediated immune response.

Any microorganism foreign to the body that can cause disease is called a pathogen. Every pathogen carries antigens on its surface that serve as targets for the immune system. These antigens have specific, identifiable markers known as epitopes, which are recognized by antibodies. B lymphocytes produce immunoglobulins; when these proteins are secreted, they circulate in the blood, recognize the epitopes on antigens, and, in most cases, neutralize the pathogen.

However, lymphocytes can sometimes make a mistake: they may confuse the body's own healthy cells with foreign invaders. When this happens, the immune system attacks the person's own cells, tissues, and organs—these are known as autoimmune diseases.With biopharmaceuticals such as monoclonal antibodies, it is possible to modulate the immune response of these lymphocytes, creating a more appropriate "immune memory" that can be either immunosuppressive or immunostimulatory. This is one of the vital areas of research developed by the Center for Research and Development in Immunobiologicals (CeRDI).