Dataset Information

Performance and Stability of Tenofovir Alafenamide Formulations within Subcutaneous Biodegradable Implants for HIV Pre-Exposure Prophylaxis (PrEP).

ABSTRACT: A critical need exists to develop diverse biomedical strategies for the widespread use of HIV Pre-Exposure Prophylaxis (HIV PrEP). This manuscript describes a subcutaneous reservoir-style implant for long-acting delivery of tenofovir alafenamide (TAF) for HIV PrEP. We detail key parameters of the TAF formulation that affect implant performance, including TAF ionization form, the selection of excipient and the exposure to aqueous conditions. Both in-vitro studies and shelf stability tests demonstrate enhanced performance for TAF freebase (TAFFB) in this long-acting implant platform, as TAFFB maintains higher chemical stability than the TAF hemifumarate salt (TAFHF). We also examined the hydrolytic degradation profiles of various formulations of TAF and identified inflection points for the onset of the accelerated drug hydrolysis within the implant using a two-line model. The compositions of unstable formulations are characterized by liquid chromatography-mass spectrometry (LC-MS) and are correlated to predominant products of the TAF hydrolytic pathways. The hydrolysis rate of TAF is affected by pH and water content in the implant microenvironment. We further demonstrate the ability to substantially delay the degradation of TAF by reducing the rates of drug release and thus lowering the water ingress rate. Using this approach, we achieved sustained release of TAFFB formulations over 240 days and maintained > 93% TAF purity under simulated physiological conditions. The opportunities for optimization of TAF formulations in this biodegradable implant supports further advancement of strategies to address long-acting HIV PrEP.

SUBMITTER: Li L

PROVIDER: S-EPMC7694512 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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Performance and Stability of Tenofovir Alafenamide Formulations within Subcutaneous Biodegradable Implants for HIV Pre-Exposure Prophylaxis (PrEP).

Li Linying L Johnson Leah M LM Krovi Sai Archana SA Demkovich Zach R ZR van der Straten Ariane A

Pharmaceutics 20201105 11

A critical need exists to develop diverse biomedical strategies for the widespread use of HIV Pre-Exposure Prophylaxis (HIV PrEP). This manuscript describes a subcutaneous reservoir-style implant for long-acting delivery of tenofovir alafenamide (TAF) for HIV PrEP. We detail key parameters of the TAF formulation that affect implant performance, including TAF ionization form, the selection of excipient and the exposure to aqueous conditions. Both in-vitro studies and shelf stability tests demonst ...[more]

PMID: 33167509

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Project description:ImportancePre-exposure prophylaxis (PrEP) is an important tool for preventing HIV infection. However, PrEP's impact on cardiometabolic health is understudied.ObjectiveTo examine the risk of incident hypertension and statin initiation among adult (age ≥18 years) health plan members starting PrEP with tenofovir alafenamide fumarate (TAF) compared with propensity score-matched adults taking tenofovir disoproxil fumarate (TDF).Design, setting, and participantsThis retrospective cohort study used electronic health records (EHRs) from Kaiser Permanente Southern California. Adult members starting PrEP in Kaiser Permanente Southern California between October 2019 and May 2022 were included. Propensity score matching with multiple imputation (50 matched data sets) was conducted to generate 1 TAF:4 TDF matched data sets with balanced baseline covariates.ExposuresPrEP initiation with either TAF or TDF during the study period.Main outcomes and measuresIncident hypertension and statin initiation within 2 years of PrEP initiation were ascertained through blood pressure and outpatient pharmacy records, respectively. Risk differences and odds ratios (ORs) were estimated using logistic regression and g-computation.ResultsA total of 6824 eligible individuals were identified (mean [SD] age, 33.9 [10.3] years; 6618 [97%] male). This pool was used to generate 2 cohorts without baseline hypertension or statin use for matching (hypertension: n = 5523; statin: n = 6149) In both cohorts, those starting PrEP with TAF were older and were more likely to be non-Hispanic White compared with those starting with TDF. In matched analysis adjusting for baseline covariates, TAF use was associated with elevated risk of incident hypertension (TAF: n = 371; risk difference, 0.81 [95% CI, 0.12-1.50]; OR, 1.64 [95% CI, 1.05-2.56]). TAF use was also associated with elevated risk of statin initiation (TAF: n = 382; risk difference, 0.85 [95% CI, 0.37-1.33]; OR, 2.33 [95% CI, 1.41-3.85]). Subgroup analyses restricted to individuals 40 years and older at PrEP initiation showed similar results with larger risk difference in statin initiation (risk difference, 4.24 [95% CI, 1.82-6.26]; OR, 3.05 [95% CI, 1.64-5.67]).Conclusions and relevanceIn this study of people taking PrEP, TAF use was found to be associated with higher incident hypertension and statin initiation compared with TDF use, especially in those 40 years or older. Continued monitoring of blood pressure and lipids for TAF users is warranted.

Project description:Long-acting (LA) administration using a subcutaneous (s.c.) implant presents opportunities to simplify administration of antiretroviral drugs, improve pharmacological profiles, and overcome suboptimal adherence associated with daily oral formulations. Tenofovir alafenamide (TAF) is a highly potent nucleoside reverse transcriptase inhibitor (NRTI) and an attractive agent for LA delivery, with a high potency and long intracellular half-life. The aim of this study was to predict minimum TAF doses required to achieve concentrations effective for HIV preexposure prophylaxis (PrEP). Daily drug release requirements were then ascertained by averaging across the dosing interval. A TAF physiologically based pharmacokinetic (PBPK) model was developed and partially qualified against available oral single- and multiple-dose pharmacokinetics. The models were assumed to be qualified when simulated values were within 2-fold of the observed mean. TAF s.c. implants were simulated in five hundred individuals, reporting predicted TAF plasma and tenofovir (TFV) plasma concentrations for various release rates. Intracellular TFV diphosphate (TFV-DP) concentrations were also simulated in peripheral blood cells and cervical and rectal tissues. The minimum dose predicted to achieve intracellular TFV-DP levels above a target concentration of 48 fmol/106 cells for a month was identified. TAF, TFV, and TFV-DP concentrations for release rates between 1.0 and 1.6 mg/day were simulated. The PBPK model indicated that a minimum release of 1.4 mg/day TAF is necessary to achieve TFV-DP concentrations above the identified target in peripheral blood mononuclear cells (PBMCs). TFV-DP cervical and rectal tissue concentrations were predicted to be between 1.5 and 2.0 fmol/106 cells and 0.9 and 1.1 fmol/106 cells, respectively, for release rates between 1.3 and 1.6 mg/day. These simulations provide target minimum doses for LA TAF PrEP in humans. Based on the generated results, multiple implants delivering a total of 1.4 mg/day of TAF subcutaneously could provide protection levels for approximately 6 months to 1 year. This modeling may inform future design of s.c. implants to mitigate adherence issues for effective PrEP applications.

Dataset Information

Performance and Stability of Tenofovir Alafenamide Formulations within Subcutaneous Biodegradable Implants for HIV Pre-Exposure Prophylaxis (PrEP).

Publications

Performance and Stability of Tenofovir Alafenamide Formulations within Subcutaneous Biodegradable Implants for HIV Pre-Exposure Prophylaxis (PrEP).

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