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Hepatitis B
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Laura Felder, Zimeng Gao, Danielle Tholey
Newer treatment agents such as tenofovir alafenamide (TAF) are available, but there are limited data on use in pregnancy. Clinical trials are ongoing, evaluating the safety and efficacy of TAF in reducing vertical transmission of HBV in pregnancy. Early data do not suggest an increased risk of congenital malformation after use in pregnancy [37]. At this time, TAF is not yet recommended for pregnant women.
Evaluating the combination of emtricitabine/ tenofovir alafenamide fumarate to reduce the risk of sexually acquired HIV-1-infection in at-risk adults
Published in Expert Opinion on Pharmacotherapy, 2021
Tenofovir alafenamide is a tenofovir prodrug that was found to be safe and efficacious against HIV infection. Compared to TDF, TAF (25 mg QD) reduces tenofovir plasma exposure (86% reduction of area under the curve during one dosing interval from 1,918 ng/ml6]. F/TAF also delivers tenofovir diphosphate intracellular blood concentrations above the 90% effective concentration more rapidly (<4 h) than F/TDF (about 3 days). TAF 10 mg has also been used in another antiretroviral combination, but since this dosing is different from the one used for PrEP, results with these drug concentrations are not reported here.
Current state-of-the-art pharmacotherapy for the management of hepatitis B infection
Published in Expert Opinion on Pharmacotherapy, 2019
Hans L. Tillmann, Gbeminiyi Samuel
Due to toxicity from tenofovir, there was an interest to limit systemic exposure, and develop an improved galenic. This was conveniently developed, just in time to the patent expiration of TDF. The new version, Tenofovir alafenamide requires a lower total dose but achieves similar antiviral efficacy, both against HBV and HIV, due to increased liver (and lymphocyte) uptake, and thus resulting in likely similar intracellular levels of TDF with lower systemic exposure. While it was for a long time promoted by some that TDF would not have a safety signal, now with the new formulation available, there is a big push, to highlight TDF’s safety concern regarding renal and bone metabolism safety [59]. It has been surprising that the concept to improve the galenic for tenofovir was only able to be achieved shortly before tenfovir disoproxil fumarate went off patent, given that data on improved galenic for adefovir resulting in improved toxicity profile had been known for long time [58]. As for the bone safety, it remains to be seen if TAF will result not only in improved bone density but reduction in bone fractures. Considering Vitamin D and calcium supplementation may be advantages, as both patients with HIV and patients with liver disease are at risk of reduced bone density [61].
Developments in pharmacotherapeutic agents for hepatitis B – how close are we to a functional cure?
Published in Expert Opinion on Pharmacotherapy, 2023
Naoshin Khan, Mohamed Ramzi Almajed, Mary Grace Fitzmaurice, Syed-Mohammed Jafri
In chronic HBV infections, interruption of treatment with antiviral agents leads to disease exacerbations and complications. An experimental ultralong-acting formulation of tenofovir alafenamide was found to sustain therapeutic drug levels at key viral replications sites such as the liver. This nanoformulation, M1TFV, recently demonstrated efficacy with antiviral activity lasting several months after a single intramuscular dose; HBV DNA suppression was maintained for 3 months [27]. In a study evaluating the contributory factors to the achievement of end-of-treatment qHBsAg<100 IU/mL, it was found that patients with hepatitis flares were more likely to achieve lower HBsAg levels, but discontinuing NA lead to further disease exacerbations including elevated ALT levels [28].