There are currently countless drugs on the market to choose from, but do we really know what the drug development process involves?
The process of developing a new drug usually takes a total of 10 to 15 years on average. The process can be divided into three main phases:
- Drug discovery, the first phase in which candidate compounds are selected based on their pharmacological properties.
- Preclinical development, a phase in which a wide range of studies are performed in the laboratory. Characteristics of the drug, such as toxicity, effects, formulation, among others, are tested.
- Clinical development, the phase of testing of the selected drug’s effectiveness, side effects, and potential risks in healthy volunteers and patients.
These phases are not necessarily performed in the strict order shown here but generally have some overlap.
Image extracted from Elsevier, Stages of Development of a New Drug
Typically, drug development begins with the identification of a “target.” The target is generally a protein associated with a human disease that the new drug is intended to impact. Once located, a “high-performance selection” process is performed, in which the molecules that bind to this target to impact or modify it are identified. These become the first candidates for the new drug.
The next step is to optimize candidate molecules to make them more specific and bind better to our target. Once optimized, a first characterization is performed of how these molecules act in the body, studying drug absorption, distribution, metabolism and elimination, among others.
This phase is one of the most important, since a large amount of data is collected on the candidate molecules. Characteristics such as toxicity, effective dose and safety are tested in animal models.
In addition, the optimal drug formulation is studied, as well as the feasibility of large-scale production, using computer models.
In this stage, we determine the so-called no observable adverse effect level (NOAEL) of the drug, which will be used to determine a safe dose range in subsequent clinical trials with patients.
Clinical development is what we know as the clinical trial, the phase in which the efficacy and safety of the drug is studied in patients. This process is often the longest and most expensive of the whole development process. Clinical development is divided into 3 phases to evaluate different aspects:
- Phase I includes the first clinical trials in a small group of volunteers to study the safety profile of the drug, including the safe dose range. These studies also determine its absorption, distribution, metabolism, and excretion, as well as its duration of action.
- In Phase II, the drug is tested in a larger group of patients with the disease studied in order to evaluate its safety, efficacy and to establish the appropriate therapeutic dose.
- Phase III includes large-scale clinical trials with several hundred to thousands of patients with the aim of establishing the safety and efficacy of the drug in the specific indications for regulatory approval. It is also possible to compare the new drug with a standard treatment and thus assess the risk-benefit ratio of the new drug.
After completing Phase III, the medicinal product enters the regulatory approval process, in which all data is reviewed in a comprehensive manner. Once approved, the drug is ready to be marketed.
Phase IV clinical trials are conducted once the drug is already on the market, and their objective is to determine and monitor the long-term effects of the drug.