Background and importance Tenofovir alafenamide (TAF) is a novel tenofovir prodrug, recently entering the market for HIV infections. TAF results in higher intracellular concentrations of the active metabolite tenofovir diphosphate compared with tenofovir disoproxil fumarate (TDF), allowing for much lower doses of TAF versus TDF. This leads to a reduction in the risk of kidney and bone disease, maintaining the same efficacy.

Aim and objectives The aim of the study was to evaluate the prescriptive trend of TDF and TAF based drugs for HIV in hospital and the switch from one formulation to the other.

Material and methods Dispensations, carried out from 1 January 2017 to 30 September 2019, of formulations containing TDF and TAF were extracted. In addition, patient switches from TDF+emtricitabine+elvitegravir+cobicistat (TDF/EMT/ELV/COB) to TAF+emtricitabine+elvitegravir+cobicistat (TAF/EMT/ELV/COB) and from TDF+emtricitabine+rilpivirine (TDF/EMT/RIL) to TAF+emtricitabine+rilpivirine (TAF/EMT/RIL) were analysed. The data collected were divided by year.

Results In 2017, 286 patients used TDF in their treatment regimen for HIV while 62 used TAF based drugs, the percentage prescriptions being 92.5% versus 7.5%, respectively. In 2018, 136 patients were treated with TDF and 223 with TAF, the percentage prescriptions being 34.5% versus 65.5%. In 2019, 44 patients used TDF and 267 TAF, the percentage prescriptions being 9% versus 91%. Eleven of 28 (39%) patients changed from TDF/EMT/ELV/COB to TAF/EMT/ELV/COB in 2017, 41% (7/17) in 2018 and 50% (2/4) in 2019. In 2018, 67% (35/52) switched from TDF/EMT/RIL to TAF/EMT/RIL and 58% (7/12) in 2019. No patient changed from TAF/EMT/ELV/COB or TAF/EMT/RIL to the corresponding TDF based drugs in the 3 year period studied.

Conclusion and relevance It is evident that the reduced toxicity of TAF resulted in a progressive reduction of the use of TDF over time and a further reduction in the future is conceivable. Therefore, it will be important to determine in future works whether only patients with specific conditions receive TDF therapy, such as those with pre-exposure prophylaxis, pregnant patients (data on the use of TAF in this category of patients are still limited) and those with hypercholesterolaemia or hypertriglyceridaemia (TDF has been shown to improve the lipid profile).

References and/or acknowledgements No conflict of interest.