How many phases are typically conducted in drug trials before approval and market entry?

In drug development, there are typically three phases of clinical trials that a drug goes through before it can receive regulatory approval and enter the market. Each phase has distinct objectives and methodologies closely regulated by health authorities to ensure the safety and efficacy of the drug.

In Phase I, the primary focus is on assessing the drug's safety, determining a safe dosage range, and identifying potential side effects. This phase usually involves a small number of healthy volunteers.

Phase II expands the study to a larger group of individuals who have the condition the drug is intended to treat. The main goals here are to evaluate the drug's efficacy and further assess its safety.

Phase III is conducted on an even larger scale and is crucial for confirming the drug's efficacy, monitoring side effects, and comparing the drug to commonly used treatments. Successful completion of this phase is essential before submitting a New Drug Application (NDA) to regulatory authorities, such as Health Canada, for approval.

After these three phases, if the data is supportive, the drug may then receive approval for market entry, leading to the final phase known as Phase IV, or post-marketing surveillance, which involves monitoring the drug's performance in the general population and discovering any long-term effects. However, Phase IV is not typically