Question

Which phase of clinical trials is typically double-blind, randomized and conducted in a heterogeneous patient population across multiple centers?

• A. Phase II
• B. Phase III
• C. Phase IV
• D. Phase 0

Hint:

Clinical trials proceed in phases, each with a different size, purpose and design. Knowing the defining features of each phase is important for both regulatory and pharmacology questions.

Answer 1

The Correct Option is B

Step 1: Brief overview of clinical trial phases.
Clinical trials are conducted in phases to progressively test a drug in humans. Each phase has specific objectives, design features, and population size.

Step 2: Phase I.
Phase I trials are the first-in-human studies. They use a small number of healthy volunteers (20-80). The focus is on safety, dose escalation, and pharmacokinetics. They are NOT typically double-blind or randomized.

Step 3: Phase II.
Phase II trials test efficacy and safety in patients with the disease. Sample sizes are moderate (100-300). They may be randomized and controlled, but are usually done in a limited number of centers and a relatively homogeneous patient group.

Step 4: Phase III - the correct answer.
Phase III trials are large-scale, multi-center, double-blind, randomized controlled trials (RCTs). They involve thousands of patients (300-3000+) from diverse populations (heterogeneous). This is the definitive phase for proving efficacy and monitoring adverse effects. It forms the basis of regulatory approval.

Step 5: Phase IV.
Phase IV (post-marketing surveillance) happens after drug approval. It monitors long-term safety, rare adverse effects, and effectiveness in real-world use. Not the standard double-blind randomized design.

Step 6: Conclusion.
The double-blind, randomized, multi-center trial in a heterogeneous patient population describes Phase III.
Answer: Option (2) — Phase III