Quantification Of Tenofovir Research Articles

Development and In-House Validation of an Enzyme-Linked Immunosorbent Assay and a Lateral Flow Immunoassay for the Dosage of Tenofovir in Human Saliva

Highly active antiretroviral therapy (HAART) includes very potent drugs that are often characterized by high toxicity. Tenofovir (TFV) is a widely used drug prescribed mainly for pre-exposure prophylaxis (PreP) and the treatment of human immunodeficiency virus (HIV). The therapeutic range of TFV is narrow, and adverse effects occur with both underdose and overdose. The main factor contributing to therapeutic failure is the improper management of TFV, which may be caused by low compliance or patient variability. An important tool to prevent inappropriate administration is therapeutic drug monitoring (TDM) of compliance-relevant concentrations (ARCs) of TFV. TDM is performed routinely using time-consuming and expensive chromatographic methods coupled with mass spectrometry. Immunoassays, such as enzyme-linked immunosorbent assays (ELISAs) and lateral flow immunoassays (LFIAs), are based on antibody–antigen specific recognition and represent key tools for real-time quantitative and qualitative screening for point-of-care testing (POCT). Since saliva is a non-invasive and non-infectious biological sample, it is well-suited for TDM. However, saliva is expected to have a very low ARC for TFV, so tests with high sensitivity are required. Here, we have developed and validated a highly sensitive ELISA (IC50 1.2 ng/mL, dynamic range 0.4–10 ng/mL) that allows the quantification of TFV in saliva at ARCs and an extremely sensitive LFIA (visual LOD 0.5 ng/mL) that is able to distinguish between optimal and suboptimal ARCs of TFV in untreated saliva.

Pre-exposure prophylaxis for HIV-negative persons with partners living with HIV: uptake, use, and effectiveness in an open-label demonstration project in East Africa.

Background: Pre-exposure prophylaxis (PrEP) can provide high protection against HIV infection and is a recommended intervention for HIV-negative persons with substantial HIV risk. Demonstration projects conducted in diverse settings worldwide illustrate practical examples of how PrEP can be delivered. This manuscript presents estimates of effectiveness and patterns of PrEP use within a two-year demonstration project of PrEP for HIV-negative members of heterosexual HIV serodiscordant couples in East Africa. Methods: The PrEP delivery model integrated PrEP into HIV treatment services, prioritizing PrEP use for HIV-negative partners within serodiscordant couples before and during the first 6 months after the partner living with HIV initiated antiretroviral therapy (ART). We measured PrEP uptake through pharmacy records and adherence to PrEP through medication event monitoring system (MEMS) bottle caps and quantification of tenofovir in plasma among a random sample of participants. We estimated HIV infections prevented using a counterfactual cohort simulated from the placebo arm of a previous PrEP clinical trial. Results: We enrolled 1,010 HIV serodiscordant couples that were naïve to ART and PrEP. Ninety-seven percent of HIV-negative partners initiated PrEP. Objective measures suggest high adherence: 71% of HIV-negative participants took ≥80% of expected doses, as recorded via MEMS, and 81% of plasma samples had tenofovir detected. Four incident HIV infections were observed (incidence rate=0.24 per 100 person-years), a 95% reduction (95% CI 86-98%, p<0.0001) in HIV incidence, relative to estimated HIV incidence for the population in the absence of PrEP integrated into HIV treatment services. Conclusions: PrEP uptake and adherence were high and incident HIV was rare in this PrEP demonstration project for African HIV-negative individuals whose partners were known to be living with HIV. Delivery of PrEP to HIV-negative partners within HIV serodiscordant couples was feasible and should be prioritized for wide-scale implementation.

Pre-exposure prophylaxis for HIV-negative persons with partners living with HIV: uptake, use, and effectiveness in an open-label demonstration project in East Africa

Background: Pre-exposure prophylaxis (PrEP) can provide high protection against HIV infection and is a recommended intervention for HIV-negative persons with substantial HIV risk. Demonstration projects conducted in diverse settings worldwide illustrate practical examples of how PrEP can be delivered. This manuscript presents estimates of effectiveness and patterns of PrEP use within a two-year demonstration project of PrEP for HIV-negative members of heterosexual HIV serodiscordant couples in East Africa. Methods: The PrEP delivery model integrated PrEP into HIV treatment services, prioritizing PrEP use for HIV-negative partners within serodiscordant couples before and during the first 6 months after the partner living with HIV initiated antiretroviral therapy (ART). We measured PrEP uptake through pharmacy records and adherence to PrEP through medication event monitoring system (MEMS) bottle caps and quantification of tenofovir in plasma among a random sample of participants. We estimated HIV infections prevented using a counterfactual cohort simulated from the placebo arm of a previous PrEP clinical trial. Results: We enrolled 1,010 HIV serodiscordant couples that were naïve to ART and PrEP. Ninety-seven percent of HIV-negative partners initiated PrEP. Objective measures suggest high adherence: 71% of HIV-negative participants took ≥80% of expected doses, as recorded via MEMS, and 81% of plasma samples had tenofovir detected. Four incident HIV infections were observed (incidence rate=0.24 per 100 person-years), a 95% reduction (95% CI 86-98%, p<0.0001) in HIV incidence, relative to estimated HIV incidence for the population in the absence of PrEP integrated into HIV treatment services. Conclusions: PrEP uptake and adherence were high and incident HIV was rare in this PrEP demonstration project for African HIV-negative individuals whose partners were known to be living with HIV. Delivery of PrEP to HIV-negative partners within HIV serodiscordant couples was feasible and should be prioritized for wide-scale implementation.

Pre-exposure prophylaxis for HIV-negative persons with partners living with HIV: uptake, use, and effectiveness in an open-label demonstration project in East Africa.

Introduction: Pre-exposure prophylaxis (PrEP) can provide high protection against HIV infection and is a recommended intervention for HIV-negative persons with substantial HIV risk, such as individuals with a partner living with HIV. Demonstration projects of PrEP have been conducted in diverse settings worldwide to illustrate practical examples of how PrEP can be delivered. Methods: We evaluated delivery of PrEP for HIV-negative partners within heterosexual HIV serodiscordant couples in an open-label demonstration project in East Africa. The delivery model integrated PrEP into HIV treatment services, prioritizing PrEP for HIV-negative partners within serodiscordant couples prior to and during the first 6 months after the partner living with HIV initiated antiretroviral therapy (ART). We measured adherence to PrEP through medication event monitoring system (MEMS) bottle caps and quantification of tenofovir in plasma among a random sample of participants. We estimated HIV infections prevented using a counterfactual cohort simulated from the placebo arm of a previous PrEP clinical trial. Results: We enrolled 1,010 HIV serodiscordant couples that were naïve to ART and PrEP. Ninety-seven percent (97%) of HIV-negative partners initiated PrEP, and when PrEP was dispensed, objective measures suggest high adherence: 71% of HIV-negative participants took ≥80% of expected doses, as recorded via MEMS, and 81% of plasma samples had tenofovir detected. A total of 4 incident HIV infections were observed (incidence rate=0.24 per 100 person-years), a 95% reduction (95% CI 86-98%, p<0.0001) in HIV incidence, relative to estimated HIV incidence for the population in the absence of PrEP integrated into HIV treatment services. Conclusions: PrEP uptake and adherence were high and incident HIV was rare in this PrEP demonstration project for African HIV-negative individuals whose partners were known to be living with HIV. Delivery of PrEP to HIV-negative partners within HIV serodiscordant couples was feasible and should be prioritized for wide-scale implementation.

A validated liquid chromatography and tandem mass spectrometric method for simultaneous quantitation of tenofovir, emtricitabine, and efavirenz in human plasma and its pharmacokinetic application

A novel, rapid, and sensitive liquid chromatography-tandem mass spectrometric method was developed and validated for the simultaneous quantification of tenofovir, emtricitabine, and efavirenz in human plasma. Nevirapine was used as an internal standard. The analytes and the internal standard were extracted from human plasma sample by solid-phase extraction technique (SPE). The reconstituted samples were chromatographed on a Chromolith ROD C18 column (50 × 4.6 mm; 5 μ) by gradient elution using a mixture of ammonium acetate buffer (5 mM) and 0.1% formic acid in acetonitrile as the mobile phase at a flow rate of 1.0 mL min−1. The calibration curve obtained was linear (r2 ≥ 0.9990) over the concentration range of 2.5–650 ng mL−1 for tenofovir and 10–4000 ng mL−1 for emtricitabine and efavirenz. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. A run time of 2.5 min for each sample made it possible to analyze more than 300 plasma samples per day. Th...

Quantification of Tenofovir in Human Plasma by Solid-Phase Extraction and High-Performance Liquid Chromatography Coupled With UV Detection

Tenofovir is used in the treatment of HIV and hepatitis virus infections. The aim of this work was to develop and validate an high-performance liquid chromatography coupled with ultraviolet detection assay that can be implemented in most laboratories for the purposes of therapeutic drug monitoring and pharmacokinetic studies. Two hundred microliters of plasma sample was used for the assay. Sample processing was carried out with solid-phase extraction. Tegafur was used as the internal standard. The chromatographic separation was achieved on a C18 reverse-phase analytic column with a mobile phase consisting of sodium phosphate buffer (pH: 6.12; 20.0 mM)-acetonitrile-tetrabutylammonium hydroxide solution (pH: 13.64; 1.14 mM) (90.0:10.0:0.3, v/v/v). The detection was at 262 nm, and the column oven was set at 35°C. The linear range of the calibration curve was 20-2000 ng/mL (r > 0.999, n = 6). The absolute extraction recoveries were 97.4% ± 2.5% and 81.6% ± 0.8% for tenofovir and tegafur, respectively. The relative standard deviations were 2.3%-3.3% for the intraday and 2.8%-5.3% for the interday analyses. The accuracy was within 100% ± 7%. The successful application of this method in a pharmacokinetic study in Chinese HIV-infected patients confirmed its robustness and reliability. A validated and reproducible method has been established to quantify the concentration of tenofovir in human plasma by high-performance liquid chromatography coupled with ultraviolet detection.

Determination of Plasma Tenofovir Concentrations Using a Conventional LC-MS Method

The quantification of tenofovir, a nucleoside reverse transcriptase inhibitor prescribed once daily, in human plasma is important due to a recent increase in its use. HPLC, however, can not easily detect and quantify tenofovir because of interfering peaks. Therefore, we developed a rapid and conventional LC-MS method, validated by estimating the precision and accuracy for inter- and intraday analysis in the concentration range of 0.019-1.567 microg/ml. The calibration curve was linear in the described concentration range. Average accuracy ranged from 95.9 to 100.7%. Relative standard deviations of both inter- and intraday assays were less than 11.6%. Recovery of tenofovir was more than 80.2%. This novel method provides a conventional, accurate and precise way to determine tenofovir in human plasma samples.