Tenofovir and emtricitabine concentrations in hair are comparable between individuals on tenofovir disoproxil fumarate versus tenofovir alafenamide-based ART

Tenofovir disoproxil fumarate (TDF) in combination with emtricitabine (FTC) is the backbone for both human immunodeficiency virus (HIV) treatment and pre-exposure prophylaxis (PrEP) worldwide. Tenofovir alafenamide (TAF) with FTC is increasingly used in HIV treatment and was recently approved for PrEP among men-who-have-sex-with-men. TDF and TAF are both metabolized into tenofovir (TFV). Antiretrovirals in plasma are taken up into hair over time, with hair levels providing a long-term measure of adherence. Here, we report a simple, robust, highly sensitive, and validated high-performance liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS)-based analytical method for analyzing TFV and FTC from individuals on either TDF/FTC or TAF/FTC in small hair samples. TFV/FTC are extracted from ~5 mg hair and separated on a column using a gradient elution. The lower quantification limits are 0.00200 (TFV) and 0.0200 (FTC) ng/mg hair; the assay is linear up to 0.400 (TFV) and 4.00 (FTC) ng/mg hair. The intra-day and inter-day coefficients of variance (CVs) are 5.39-12.6% and 6.40-13.5% for TFV and 0.571-2.45% and 2.45-5.16% for FTC. TFV concentrations from participants on TDF/FTC-based regimens with undetectable plasma HIV RNA were 0.0525 ± 0.0295 ng/mg, whereas those from individuals on TAF/FTC-based regimens were 0.0426 ± 0.0246 ng/mg. Despite the dose of TFV in TDF being 10 times that of TAF, hair concentrations of TFV were not significantly different for those on TDF versus TAF regimens. Pharmacological enhancers (ritonavir and cobicistat) did not boost TFV concentrations in hair. In summary, we developed and validated a sensitive analytical method to analyze TFV and FTC in hair and found that hair concentrations of TFV were essentially equivalent among those on TDF and TAF.

Detection and quantification of Covid-19 antiviral drugs in biological fluids and tissues

Since coronavirus disease 2019 (COVID-19) started as a fast-spreading pandemic, causing a huge number of deaths worldwide, several therapeutic options have been tested to counteract or reduce the clinical symptoms of patients infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently, no specific drugs for COVID-19 are available, but many antiviral agents have been authorised by several national agencies. Most of them are under investigation in both preclinical and clinical trials; however, pharmacokinetic and metabolism studies are needed to identify the most suitable dose to achieve the desired effect on SARS-CoV-2. Therefore, the efforts of the scientific community have focused on the screening of therapies able to counteract the most severe effects of the infection, as well as on the search of sensitive and selective analytical methods for drug detection in biological matrices, both fluids and tissues. In the last decade, many analytical methods have been proposed for the detection and quantification of antiviral compounds currently being tested for COVID-19 treatment. In this review, a critical discussion on the overall analytical procedure is provided, i.e (a) sample pre-treatment and extraction methods such as protein precipitation (PP), solid-phase extraction (SPE), liquid–liquid extraction (LLE), ultrasound-assisted extraction (UAE) and QuEChERS (quick, easy, cheap, effective, rugged and safe), (b) detection and quantification methods such as potentiometry, spectrofluorimetry and mass spectrometry (MS) as well as (c) methods including a preliminary separation step, such as high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) coupled to UV–Vis or MS detection. Further current trends, advantages and disadvantages and prospects of these methods have been discussed, to help the analytical advances in reducing the harm caused by the SARS-CoV-2 virus.

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Fourteen antiviral drugs were tested to counteract the effects of COVID-19.

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A review of analytical methods for antivirals detection is presented.

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Method validation, drugs extraction, separation and detection are discussed.

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LC-MS and MS/MS is mostly used for accurate and sensitive drugs quantification.

Emtricitabine

Emtricitabine (Emtriva, FTC) is an antiviral medicine which decreases the body's amount of HIV. Emtricitabine on of Anti-HIV drugs slow down or protect the immune system against damage and reduce the risk of diseases related to developing of AIDS. Emtricitabine use also for treatment of hepatitis B virus. Emtricitabine is a drug class known as nucleoside reversing transcriptase inhibitors (NRTIs). In view of Emtricitabine's clinical significance, a thorough review of the physical and pharmaceutical characteristics and details of the multiple analytical techniques used to test the drug in pharmaceutical and biological systems was conducted. The methods investigated include identification test, Spectroscopy, chromatography, electrochemicals, and Thermal. Beside the analytical profile, the degradation and stability of Emtricitabine, its pharmacology and pharmacokinetics, Pharmaceutical Applications, Mechanism of Action, dosage forms and dose, ADME profile, and interactions have been debated.

Overview of the Chromatographic and Mass Spectrometry Analytical Methods for Determination of Lamivudine in Biological Fluids

Background:

Lamivudine was approved by Food and Drug Administration of the United States for the treatment of both HIV and HBV infection, which has been widely used as monotherapy or a component of combination therapy in clinics in many countries and nationalities.

Methods:

In this paper, the recent chromatographic and mass spectrometry analytical methods for the determination of lamivudine individually or combination with other drugs simultaneously were presented. These methods were widely applied in pharmacokinetics studies, bioequivalence studies, therapeutic drug monitoring studies, cell and animal experiments.

Conclusion:

The review paper might provide references for determining lamivudine in biological fluids, the intracorporal process of lamivudine, and the clinical practice by monitoring plasma concentration of lamivudine in the future.

A LC/MS/MS method for determination of tenofovir in human plasma and its application to toxicity monitoring

Tenofovir disoproxil fumarate is a pro-drug of the active metabolite tenofovir widely used against the HIV1, HIV2, and Hepatitis B virus. Several studies have been conducted and found kidney injury associated with tenofovir exposure. High tenofovir plasma concentration correlated with kidney injury in tenofovir-exposed patients. The present study developed and validated a simple and cost-effective LC/MS/MS method to determine tenofovir level in human plasma. A small plasma volume of 80 μl is utilized for the sample preparation. The samples were separated by Luna C18 (100 mm × 2.0 mm, 3 μm) using gradient elution with a mobile phase consisting of water (containing 0.1% formic acid) and acetonitrile (90:10, v/v). The detection was achieved through multiple reaction monitoring using positive ionization mode on the triple quadrupole mass spectrometer with a run time of 10 min. The monitoring transitions were set at m/z 288.0 → 176.1 and 136.1 for tenofovir and m/z 226.1 → 152.0 for acyclovir (as the internal standard). This standard curve was linear from 10 to 640 ng/ml, with the lower limit of quantification of 10 ng/ml. The inter- and intra-day precision results were less than 12.3% and their accuracies were within the acceptable range of 84.9-113.1%. The validated method was successfully applied to the study of tenofovir induced kidney injury in HIV-1 infected patients taking 300 mg once daily for more than 4 weeks.

Assay development for determination of tenofovir in human plasma by solid phase analytical derivatization and LC-MS/MS

BACKGROUND

A novel method was developed and validated to measure tenofovir in human plasma. RESULTS/METHODOLOGY: This method employed solid phase analytical derivatization and analysis by LC-MS/MS. Stable-labeled internal standard was added to plasma samples followed by solid phase extraction. Retained analytes were derivatized on the solid phase extraction cartridges with a diazomethane solution to yield methyl-ester derivatives. Samples were analyzed using LC-MS/MS incorporating the use of a strong cation exchange column. The method was validated over a range of 5.00-750 ng/ml. The approach developed in this report for tenofovir could be applied to other analytes that share similar structural similarities.

CONCLUSION

The tenofovir LC-MS/MS method was used to support a clinical study of over 400 samples with a 100% success rate.

An Investigation of Liquid Chromatography-Mass Spectral Attributes and Analytical Performance Characteristics of Tenofovir, Emtricitabine and Efavirenz in Human Plasma

Liquid chromatography (LC) and mass spectral behavior and analytical performance characteristics of efavirenz (EFV), emtricitabine (EMT) and tenofovir (TFV), i.e., individual components of Atripla(®), were probed. This was followed by estimation of their analytical performance characteristics employing LC and a parallel direct infusion sample introduction procedure. Performance characteristics using both types of sample introduction procedures were compared. Using liquid chromatography-mass spectrometry (LC-MS), linearities, i.e., correlation coefficients of the calibration curves of EFV, EMT and TFV, ranged between 0.9300 and 0.9990 in the full scan, selected ion monitoring and mass spectrometry/mass spectrometry (MS-MS) modes. The limits of detection (LODs) ranged between 0.5 and 11.6 µg/L. The lower limits of quantification (LLOQs) and the upper limits of quantification (ULOQs) were in the ranges of 0.9-23.2 and 1.6-38.7 µg/L, respectively. The LODs ranged between 0.8 and 114.7 µg/L. The LLOQs and the ULOQs were in the ranges of 1.6-29.4 and 2.7-49.0 µg/L, respectively. In the case of EMT, sodiated molecular ion at m/z 270 was used to adduce analytical performance characteristics from which lower detection limits were obtained compared with those in the literature where [M+H](+) at m/z 248 was used.

Incurred sample reanalysis (ISR): a decisive tool in bioanalytical research

The AAPS Workshop 2008 on Current Topics in GLP Bioanalysis: Assay Reproducibility for Incurred Samples was the defining moment in establishing incurred sample reanalysis (ISR) as a mandatory exercise in demonstrating assay reproducibility using incurred (study) samples. The importance of ISR can be envisaged from its role in clinical as well as non-clinical studies. Incurred samples can differ significantly in their composition when compared with the calibration standards and quality control samples that are used to validate the developed method. The present article attempts to summarize five troubleshooting cases encountered in the analyses of incurred samples for bioanalytical methods developed in our laboratory for mesalamine, hydrochlorothiazide, clopidogrel, sildenafil and rabeprazole. The issues identified were related to: sample inhomogeneity, sample processing error, impact of buffer pH during sample preparation, instability of metabolite and change in laboratory environment. The steps taken to trace and correct these incidents are discussed with adequate data. These examples will further broaden the scope and emphasize the significance of ISR. We believe this investigation will help to develop more reliable and efficient bioanalytical methods.