Background and Importance The Preexposure Prophylaxis (PrEP) for HIV infection with the drugs tenofovir and emtricitabine (FTC/TDF) is recommended by World Health Organization as part of HIV prevention to people at substantial risk HIV infection. Many countries have included it in their healthy police. However, there is a lack of information on its implementation in real practice.

Aim and Objectives To evaluate adherence, the effectiveness and safety to treatment for PrEP.

Material and Methods A retrospective and descriptive study of all adult patients who used FTC/TDF for PrEP from September 2020 to September 2022. Clinical data were obtained from digital clinical history and the prescription software Dominion^®: sex, age, duration of treatment, high-risk for HIV and adherence to treatment.

The adherence to treatment was measured using the dispensing registry. Effectiveness was determined by relative reduction of HIV incidence; HIV testing was performed every three months during this study. In terms of safety, adverse events (AE) were recorded.

Results Forty patients, 100% men, were included, with an average aged of 35 (20-57) years. All patients were received (FTC/TDF), once daily. The average duration of treatment was 6 months (1-30), 8 patients received only two months. All patients were at high risk for HIV, defined as: sexual risk behaviour (ten or more sexual partners and any bacterial sexually transmitted infections (STIs) last year). 25% patients had discontinued therapy due to lack of adherence.

None of these patients were diagnosed HIV during study. 100% relative reduction of HIV incidence.

No treatment-associated adverse effects were observed, although 75% of patients had PrPE-associated bacterial STIs.

Conclusion and Relevance

• A quarter of patients were non-adherent to treatment, a possible alternative would be on-demand regimen in these cases.

• In terms of efficacy, a greater therapeutic result was observed, becoming a good tool prevention.

• PrEP used was associated high increased bacterial STIs, probably due to not using a condom.

Conflict of Interest No conflict of interest