Final answer:
The trial phase for determining a drug's effectiveness and long-term safety is the Phase III clinical trial. It involves a large number of patients and includes pharmacokinetic analysis for different sub-populations. Success in this phase leads to submission for FDA approval followed by postmarketing surveillance or Phase IV clinical trials.
Step-by-step explanation:
Phase III Clinical Trials
The trial phase concerned with determining a drug's effectiveness, long-term safety, and confirming findings is typically the Phase III clinical trial. This phase involves extensive studies with several thousands of patients to establish the efficacy and safety profile of a compound, enabling accurate drug labeling. Pharmacokinetic analysis during this phase is specialized for various sub-populations, such as those with impaired renal or hepatic functions, as well as pediatric and elderly populations.
Phase I clinical trials focus mainly on assessing the safety and tolerability of a compound in humans, including its pharmacokinetic properties such as absorption and elimination. If a drug is not well tolerated or has unsuitable pharmacokinetic properties, it is dropped from development. On the other hand, Phase II clinical trials assess dose response and establish effective dosing that will be used in Phase III.
After successful completion of Phase III, if the drug is deemed effective and safe, a New Drug Application (NDA) is submitted for FDA approval. If approved, postmarketing surveillance, known as Phase IV, commences, during which additional trials or risk management plans might be required to ensure ongoing safety.