27 January, 2026
Author : Dr Vijaykumar Gawali

Topic : KEY RESPONSIBILITIES OF THE INVESTIGATOR DURING A CLINICAL TRIAL

1 Definition

The Principal Investigator (PI) is the medically responsible leader for the trial at the site.
ICH-GCP clearly states that PI carries full accountability for participant safety and trial integrity, although duties may be delegated.

2 PI Responsibilities Explained for CRC Understanding

2.1 Identifying Eligible Participants

PI ensures:

• correct application of inclusion & exclusion criteria
• verification of supporting documents
• confirmation of protocol-defined eligibility

The CRC supports by preparing:

• screening worksheets
• diagnostic reports
• medical history summaries

2.2 Providing Medical Care Throughout the Study

Includes:

• clinical assessments
• reviewing adverse events
• treating complications
• emergency management
• deciding on continuation/discontinuation

CRC aids by:

• documenting AE details
• scheduling follow-ups
• tracking lab results

2.3 Training and Supervising Site Team

PI must:

• train sub-investigators, CRCs, nurses, pharmacy staff
• document all trainings in logs
• review and sign the Delegation Log

CRC helps:

• organize training meetings
• maintain attendance & signatures

2.4 Attending to Adverse Events and Safety Reporting

PI responsibilities:

• assess severity, causality, expectedness
• sign all SAE reports
• ensure 24-hour reporting to sponsor & EC
• ensure Day-14 analysis submission to CDSCO

CRC prepares:

• Table-5
• narratives
• copies of ICF, protocol, SOC

2.5 Interacting with CRA & Handling Audits

PI:

• attends monitoring visits
• clarifies medical & clinical decisions
• reviews monitoring findings
• supports CAPA implementation

CRC ensures:

• availability of PI
• source notes & CRFs ready
• ISF complete

2.6 Ensuring Adequate Infrastructure

PI ensures availability of:

• calibrated equipment
• emergency care facilities
• IP storage & backup
• laboratory capability

CRC documents:

• calibration certificates
• storage temperature logs
• equipment validation records

3 Step-by-Step PI Oversight Workflow (CRC Support Guide)

• PI reviews protocol → CRC arranges training
• PI reviews first patients → CRC organizes OPD screening
• PI signs eligibility → CRC prepares documentation
• PI reviews AE/SAE → CRC drafts forms
• PI reviews IP accountability → CRC provides logs
• PI meets CRA → CRC prepares agenda
• PI signs CRFs → CRC routes documents