Background and Importance Pre-exposure prophylaxis against HIV infection (PrEP) consists of the prescription of tenofovir disoproxil fumarate and emtricitabine (TDF/FTC) in people risk of acquiring the infection. PrEP is part of the package of measures of health agencies aimed at preventing HIV.

Aim and Objectives The objective of this study is to evaluate the effectiveness and safety of treatment with TDF/FTC for HIV pre-exposure prophylaxis, as well as therapeutic adherence in a third-level hospital.

Material and Methods Retrospective, observational study including patients who received for a minimum of 4 months, Prep with TDF/FTC (March 2020-May 2022).The data have been obtained through the patient‘s clinical history and outpatient dispensing module. The variables collected were: age, sex, duration of treatment, reason for suspension, number of partners in the last year, sexually transmitted infections (STIs) before and during treatment, use of chemsex, administration schedule, adverse drug reactions, serum creatinine, prior administration of post-exposure prophylaxis (PEP) and HIV serology during treatment. Safety was assessed by reporting adverse reactions during the study and renal function before and after starting treatment. The effectiveness was evaluated according to the results of HIV serologies.

Results 63 patients were included, all of them HIV-negative men, mean age of 36.7 years. All patients met criteria for initiation PrEP.15.9% of the included patients had been treated at least once with PEP,63.5% had had more than 10 partners in the last year, 63.5% did not use chemsex, 17.5% occasionally and the rest regularly. 79.4% of the patients had contracted STIs before starting treatment and 55.6% after. The most common STIs were syphilis, gonorrhea, ureaplasma urealyticum and chlamydia. Only 7 patients did not have any STIs before or during treatment. 95.2% opted for the daily administration and only 3 patients the alternative regimen. Regarding safety, 10 patients reported any adverse reaction, the majority were digestive: diarrhoea and nausea,1 patient with increased transaminases and 1 patient with increased creatinine serum. Only 8 patients suspended treatment, 3 of them due to adverse reactions. Concerning adherence, the 90,5% were considered adherent to treatment.

Conclusion and Relevance All patients remained negative for HIV 1–2 serology during the study. Only 3 patients discontinued treatment due to adverse reactions and only 1 had worsening renal function. Adherence to treatment was good. It is necessary to insist on the recommendation of condom use in this patient population to prevent other STIs.

Conflict of Interest No conflict of interest.