Who should be responsible for all trial-related medical decisions?

• A. The sponsor's medical director.
• B. A qualified physician (or dentist when appropriate) who is an investigator or a sub-investigator for the trial.
• C. Any clinician chosen by the subject.
• D. The trial nurse practitioner.

Answer: (B)

Medical decisions for trial participants must be made by a qualified physician (or dentist when appropriate) who is an investigator or sub-investigator for the trial. This person has the clinical training and formal role within the study to interpret the protocol, assess safety, and make treatment decisions consistent with participant welfare and study procedures. The sponsor’s medical director provides oversight and safety monitoring at the sponsor level, not day-to-day medical decisions for each participant. Allowing any clinician chosen by the subject to make all medical decisions would bypass the standardized, protocol-driven care required for the trial, while a nurse practitioner may assist as part of the study team but does not replace the need for a medically qualified investigator or sub-investigator who is explicitly designated for the trial.