The development of a new drug is a true scientific odyssey, marked by rigorous steps, complex challenges, and strict regulations. This journey, which can span a decade or more, begins long before the product ever reaches the hands of patients.

It all starts in the laboratory, where researchers delve into the root causes of a disease. They identify a therapeutic target — a protein, enzyme, or receptor — that plays a key role in the pathological mechanism. Once the target is pinpointed, thousands of molecules are screened in the hope of finding one that interacts effectively with it. Promising compounds are then refined and optimized to enhance their efficacy while minimizing side effects.

Next comes the preclinical phase, during which the candidate drug undergoes a series of tests — first on cells (in vitro), then on animals (in vivo). These studies assess toxicity, pharmacokinetics (how the drug is absorbed, distributed, metabolized, and excreted), and pharmacodynamics (its biological effects). The goal is clear: to determine whether the drug is safe and potentially effective enough to be tested in humans.

If the results are encouraging, the project enters the realm of clinical trials — a crucial stage divided into several phases.

• Phase I involves a small group of healthy volunteers to evaluate safety and determine the appropriate dosage.
• Phase II includes patients with the targeted condition to assess the drug’s efficacy and monitor side effects.
• Phase III involves a large number of patients to confirm the drug’s benefits, detect rare adverse reactions, and compare it with existing treatments.

Once these steps are completed, the data is compiled into a dossier submitted to health authorities — such as the EMA in Europe or the FDA in the United States. These regulatory agencies thoroughly review the clinical trial results before granting, if all criteria are met, marketing authorization.

But the journey doesn’t end there. In many countries, including France and Belgium, authorities then evaluate the medical benefit provided by the drug to set its price and determine its reimbursement rate. This step is essential to ensure that patients have access to the treatment.

Even after the drug is launched on the market, it continues to be monitored. Through pharmacovigilance — also known as Phase IV of clinical research — side effects observed in real-world conditions are recorded and analyzed. The benefit-risk ratio is regularly reassessed, ensuring ongoing safety for patients.