Useful references to read:-
EMA EC HMA RECOMMENDATION PAPER ON DECENTRALISED ELEMENTS IN CLINICAL TRIALS 13 Dec 2022

FDA Decentralized Clinical Trials for Drugs, Biological Products, and Devices Guidance for Industry, Investigators, and Other Stakeholders DRAFT GUIDANCE May 2023
FDA draft might be useful:-
“A central distribution service could be used to ship the IP directly to trial participants. The investigator or delegated trial personnel must control the release of the IP by the distributor; monitor receipt and use by trial participants (or participants’ legally authorized representatives), according to procedures described in the protocol; and monitor the return or disposal of any unused product as directed by the sponsor.
The protocol should describe how investigators will track and document that trial participants (or participants’ legally authorized representatives) receive IPs. “


You might find this EMA Q&A useful:-
https://www.ema.europa.eu/en/human-r...l-practice-gcp
“The investigator should retain the final decision on whether the service provider, intended to support the investigator, is appropriate. The investigator also retains the ultimate responsibility for any tasks involving trial-related medical decisions (e.g. participant eligibility and enrolment, protocol specified medical procedures, assessment of efficacy/safety, evaluation of test results, decision to dispense or make changes to the trial medication) and, the appropriate supervision of the persons or parties undertaking the activities delegated.
Any trial related procedure that is delegated to a service provider should be specified in a written agreement. Where the agreement is between the sponsor and the service provider and involves tasks under investigator responsibility, it should be clear in the agreement between the sponsor and the service provider as well as in the agreement between the sponsor and the investigator that the investigator maintains adequate control and oversight over the contracted tasks.”