SOCRA Clinical Trial Design and Phases — Questions and Answers
Question 1: What is the primary objective of a Phase I clinical trial?
- Confirm efficacy in a large population
- Assess safety, tolerability, and pharmacokinetics, usually in a small number of subjects (Correct answer)
- Compare the drug with standard therapy for marketing approval
- Monitor long-term safety after approval
Correct answer: Assess safety, tolerability, and pharmacokinetics, usually in a small number of subjects
Phase I trials are first-in-human studies, usually in 20–80 subjects (often healthy volunteers). They focus on safety, tolerability, dosing, and pharmacokinetics.
Question 2: In a double-blind trial, who does not know the subjects' treatment assignments?
- Only the subjects
- Only the statistician
- Both the subjects and the investigators/study staff (Correct answer)
- Only the sponsor
Correct answer: Both the subjects and the investigators/study staff
In a double-blind trial, neither the subjects nor the investigators and study staff who assess them know who is getting which treatment. This reduces bias in both reporting and assessment.
Question 3: What is the main purpose of randomization in a clinical trial?
- To make enrollment faster
- To ensure every subject gets the active drug
- To reduce selection bias and balance known and unknown confounders between groups (Correct answer)
- To remove the need for a control group
Correct answer: To reduce selection bias and balance known and unknown confounders between groups
Random assignment prevents investigators from choosing who gets which treatment and tends to balance baseline characteristics across groups. This supports valid comparisons.
Question 4: Under an intention-to-treat (ITT) analysis, subjects are analyzed:
- According to the treatment they actually received
- Only if they completed the study per protocol
- In the group they were randomized to, regardless of adherence or withdrawal (Correct answer)
- Only if they had no protocol deviations
Correct answer: In the group they were randomized to, regardless of adherence or withdrawal
ITT analyzes subjects in the group they were originally randomized to. This preserves the benefit of randomization and reflects real-world effectiveness.
Question 5: Which type of study is typically conducted after a product has received marketing approval?
- Phase I
- Phase II
- Phase III
- Phase IV (Correct answer)
Correct answer: Phase IV
Phase IV (post-marketing) studies look at long-term safety, rare adverse events, new populations, or additional uses after approval.
Question 6: In a crossover design, which statement is true?
- Each subject receives only one treatment for the whole study
- Each subject receives the treatments being compared in sequence, often with a washout period in between (Correct answer)
- Subjects are never randomized
- It is used mainly for acute, curable conditions
Correct answer: Each subject receives the treatments being compared in sequence, often with a washout period in between
In a crossover trial, each subject receives the treatments being compared in sequence, so each subject acts as their own control. A washout period reduces carryover effects. This design works best for stable, chronic conditions.
