Background and importance Tenofovir disoproxil (TDF) is a nucleotide reverse transcriptase inhibitor (NTRTI) used for the treatment of HIV-1 infections in combination with other antiretrovirals. In 2016, the main TDF therapeutic regimens in our centre were: emtricitabine (FTC)/TDF/rilpivirine (RVP), FTC/TDF/elvitegravir (EVG)+cobicistat (COBI), FTC/TDF/efavirenz (EFV) and FTC/TDF in combination with other drugs. Starting from the same year, these formulations were marketed (except for FTC/TDF/EFV), containing tenofovir alafenamide (TAF) instead of TDF. TAF is a chemical precursor of TDF which has demonstrated high antiviral efficacy comparable with TDF but at a lower dosage and with fewer side effects (kidney and bone diseases). Furthermore, in 2018 and 2019, additional formulations containing the TAF were produced even though there was no corresponding formulation for TDF.

Aim and objectives The purpose of the study was to analyse the variation in therapeutic regimens from the marketing of TAF formulations in the 2016–2019 4 year period.

Material and methods Patient dispensations were analysed, extracting data from the information system. The focus was on prescriptive trends with TDF based TAF based formulations.

Results At the beginning of 2016, 4526 out of 6405 (70.66%) patients were treated with TDF, as follows: 1127 with FCT/TDF/EFV (24.90%), 1207 with FTC/TDF/RVP (26.68%), 457 with FTC/TDF/EVG+COBI (10.09%) and 1735 with FTC/TDF in combination with other antiretrovirals (38.33%). In 2017, TDF therapies were 3599 (55.69%) and TAF therapies 1175 (18.18%) of 6463. In 2018, TDF based regimens were 2542 (38.99%) and TAF based regimens 2268 (34.79%) of 6518. At the end of 2019, 2184 out of 6571 patients (33.23%) were treated with TDF and those with TAF were 2679 (40.77%). In comparison with the starting point, in 2019 TDF based therapies included: 648 with FCT/TDF/EFV (29.67%), 767 with FTC/TDF/RVP (35.12%), 0 with FTC/TDF/EVG+COBI and 769 with FTC/TDF in combination with other antiretrovirals (35.21%). TAF based therapies included: 708 with FTC/TAF/RVP (26.43%), 136 with FTC/TAF/EVG+COBI (5.08%), 592 with FTC/TAF/bictegravir (BIC) (22, 10%), 690 with FTC/TAF/DRV+COBI (25.75%) and 553 with FTC/TAF in combination with other drugs (20.64%).

Conclusion and relevance Analysis of prescriptions in 2016–2019 showed a decrease in TDF based therapies in favour of TAF based prescriptive regimens. Although TDF formulations remained a valid therapeutic opportunity, TAF formulations, with minor kidney and bone side effects, are an even more relevant alternative for physicians.

Conflict of interest No conflict of interest