Study Overview: This study is testing rectal inserts of two drugs, TAF and EVG, to see if they are safe and how they move through the body. The study helps learn more about using these drugs to keep people from getting HIV. It's a double-blind study, meaning neither the participants nor the researchers know who gets the real drug or a placebo (a fake treatment).

Participation Details: In the study, participants will use the inserts for 3 days straight, then every other day for 14 days. They will visit the clinic several times for sample collection. A washout period (break from the study) will last 7 to 28 days between phases.

• The study lasts several weeks with multiple clinic visits.
• Participants must be HIV-negative and meet specific health criteria.
• Risks include discomfort from sample collections and possible drug side effects.

Who Can Join? Participants must be 18-59 years old, able to give consent, and have a history of receptive anal intercourse. They must also be willing to use certain contraception methods.

Who Cannot Join? Individuals with liver or kidney disease, certain past surgeries, or current use of specific medications cannot participate. Pregnant or breastfeeding people are also excluded.