Pre-exposure prophylaxis is taken by people who are HIV-negative to prevent HIV acquisition. It is prevention, and the people using it do not have HIV. Excluding a PrEP user from a non-HIV trial removes an HIV-negative participant for a reason that has nothing to do with HIV infection. PrEP use is therefore not a basis for exclusion, as stated in Requirement 4.5.

A participant on PrEP is eligible once the regimen has been stable for at least 30 days and no drug-drug interaction with the investigational product has been identified. The 30-day window reflects the time most PrEP regimens need to reach steady state. It is shorter than the 3-month stability window used for treatment in people living with HIV, and the two should not be conflated. See the decision tree above and the PrEP entry in the language library below.

Common PrEP regimens have well-characterized pharmacokinetics. Oral options include tenofovir-based combinations such as TDF/FTC and TAF/FTC. Long-acting injectable options include cabotegravir and lenacapavir, given at extended intervals. Where a long-acting injectable is used, the dosing schedule and the agent’s interaction profile should be assessed against the investigational product using the same tiered approach applied to treatment, rather than handled by blanket exclusion.

For a PrEP user, the protocol record should note the regimen, the date it started or was last administered, and the result of the interaction assessment. Responsibility for this sits with the sponsor. No HIV-specific eligibility assessment beyond the interaction check is required, since the participant is HIV-negative.