Which phase is performed to examine drug effectiveness in the general population post-commercialization?

The phase that is performed to examine drug effectiveness in the general population post-commercialization is Phase 4. In this phase, studies are conducted after the drug has already received regulatory approval and is available for public use. The primary focus is on the long-term effectiveness and safety of the drug, as it is used in a larger and more diverse population than in earlier phases.

Phase 4 trials often seek to identify any rare side effects or interactions that were not evident in earlier testing. These studies help to further understand how the drug performs in everyday clinical settings and among various demographics, which is vital for ongoing pharmacovigilance.

In contrast, Phase 1 trials primarily assess safety and dosage; Phase 2 trials evaluate effectiveness and further assess safety among a larger group; and Phase 3 trials compare the new drug's effectiveness against standard treatments or placebos before it can be approved for general use. Thus, the purpose and timing of each trial phase are distinct, underscoring the role of Phase 4 in real-world drug evaluation and monitoring.