Comparison of efficacy of a new drug B with an existing drug A is done in which phase of clinical trials ?
**Core Concept**
The question requires understanding of the different phases of clinical trials, specifically the phase where a new drug is compared to an existing one. This involves knowledge of **clinical trial design** and the purpose of each phase.
**Why the Correct Answer is Right**
The correct phase for comparing the efficacy of a new drug (Drug B) with an existing drug (Drug A) is Phase III. This phase involves **randomized controlled trials** where the new drug is compared to the standard treatment (in this case, Drug A) to determine its efficacy and safety in a larger population.
**Why Each Wrong Option is Incorrect**
**Option A:** Phase I trials are primarily concerned with assessing the safety of a new drug, not comparing its efficacy to another drug.
**Option B:** Phase II trials may involve some comparison but are mainly focused on determining the optimal dose and getting an initial idea of the drug's efficacy.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that Phase III trials are crucial for **drug approval** as they provide the necessary data on the drug's efficacy and safety profile compared to existing treatments.
**Correct Answer:** Correct Answer: C. Phase III.