Authorised health care professional
This term and its definition in the 2004 legislation has been removed. The Medicines for Human Use (Clinical Trials) (Amendment) Regulations 2025 say that the chief investigator should be a ‘health care professional’ (the definition of a health care professional is provided below).
Chief investigator
The chief investigator (CI) must be a health care professional and is the lead investigator who takes responsibility for the overall conduct of the trial. In relation to a clinical trial conducted at a single trial location this will be the investigator for that location.
In relation to a clinical trial conducted at more than one trial location, this will be a health care professional, whether or not that health care professional is an investigator at any particular location, who will take primary responsibility for the conduct of the trial.
The roles and responsibilities of the chief investigator have not changed under the amended regulations, and they must be qualified and appropriately trained to undertake the role. The change only relates to who can take on the role.
Health care professional
This definition applies to both chief investigators and investigators. A ‘health care professional’ will be defined as any of the following:
- a doctor
- a dentist
- a registered nurse as defined in regulation 8(1) of the Human Medicines Regulations 2012
- a pharmacist
- a person registered in a register of ophthalmic opticians maintained under section 7(a) of the Opticians Act 1989
- a person registered in the Health and Care Professions Council register (as defined in regulation 8(1) of the Human Medicines Regulations 2012) as a member of a relevant profession within the meaning of article 2 of, and paragraph 1 of Schedule 3 to, the Health Professions Order 2001
- a registered osteopath as defined by section 41 of the Osteopaths Act 1993
- a registered chiropractor as defined by section 43 of the Chiropractors Act 1994
- a person registered under the Anaesthesia Associates and Physician Associates Order 2024
- a registered midwife as defined in regulation 8(1) of the Human Medicines Regulations 2012
Investigator
An investigator, in relation to a clinical trial, is defined as a health care professional who is responsible for the conduct of that trial at that trial location (or, if there is more than one, the trial locations) and who is, if the trial is conducted by a team of health care professionals at that location or locations, the leader responsible for that team. Investigators must be appropriately trained to undertake the role in a clinical trial.
The terms ‘investigator’ and ‘principal investigator’ are considered to be interchangeable as they both refer to the investigator who takes the lead investigator role at a trial location.
Participant (formerly 'subject')
The definition of a participant in a clinical trial is an individual, whether a patient or not, who participates in a clinical trial either as a recipient of an investigational medicinal product (or of some other treatment or product), or without receiving any treatment or product, as a control.
Trial location (formerly 'trial site')
The definition of ‘trial location’, in relation to a clinical trial, will mean a hospital, health centre, surgery or other establishment, or facility or premises at or from which a clinical trial, or any part of such a trial, is conducted.
This terminology has changed to better reflect that trial activity can take place at a range of locations and is no longer limited to traditional hospital or clinical settings. For example, clinical trial activity may be conducted at participants’ homes or mobile units.
For the purposes of our guidance we may still use the term ‘site’ when we refer to the organisation that has the legal responsibility for the study and/or duty of care for the participants.