Alessandra Ariaudo

HPLC–MS method for the simultaneous quantification of the antileukemia drugs imatinib, dasatinib and nilotinib in human peripheral blood mononuclear cell (PBMC)

A new method using high performance liquid chromatography coupled with electrospray mass spectrometry is described for the quantification of PBMC concentration of tyrosine kinase inhibitors imatinib, dasatinib and nilotinib. A simple PBMC isolation and extraction procedure were applied on 10-14 mL of blood aliquots. Chromatographic separation of drugs and Internal Standard (quinoxaline) was achieved with a gradient (acetonitrile and water+formic acid 0.05%) on a C18 reverse phase analytical column with 25 min of analytical run, at flow rate of 0.25 mL/min. Mean intra- and inter-day precision for all compounds were 8.76 and 12.20%; mean accuracy was -3.86%; extraction recovery ranged within 79 and 91%. Calibration curves ranged from 50.0 to 0.25 ng. The limit of quantification was set at 0.25 ng for all the analyzed drugs. This novel developed methodology allows a specific, sensitive and reliable simultaneous intracellular determination of the three tyrosine kinase inhibitors imatinib, dasatinib and nilotinib in a single chromatographic run, useful for drugs estimation in PBMC of patients affected by chronic myeloid leukemia.

Development and validation of a new method to simultaneously quantify triazoles in plasma spotted on dry sample spot devices and analysed by HPLC-MS

OBJECTIVES Therapeutic drug monitoring (TDM) of triazoles is widely used in clinical practice to optimize therapy. TDM is limited by technical problems and cost considerations, such as sample storage and dry-ice shipping. We aimed to develop and validate a new method to analyse itraconazole, posaconazole and voriconazole in plasma spotted on dry sample spot devices (DSSDs) and to quantify them by an HPLC system. METHODS Extraction from DSSDs was done using n-hexane/ethyl acetate and ammonia solution. Samples were analysed using HPLC with mass spectrometry (HPLC-MS). Accuracy and precision were assayed by inter- and intra-day validation. The stability of triazoles in plasma spotted on DSSDs was investigated at room temperature for 1 month. The method was compared with a validated standard HPLC method for quantification of triazoles in human plasma. RESULTS Mean inter- and intra-day accuracy and precision were <15% for all compounds. Triazoles were stable for 2 weeks at room temperature. The method was linear (r(2) > 0.999) in the range 0.031-8 mg/L for itraconazole and posaconazole, and 0.058-15 mg/L for voriconazole. High sensitivity was observed; limits of detection were 0.008, 0.004 and 0.007 mg/L for itraconazole, posaconazole and voriconazole, respectively. A high degree of correlation (r(2) > 0.94) was obtained between the DSSD method and the standard method of analysis. CONCLUSIONS The method that we developed and validated to quantify triazoles in human plasma spotted on DSSDs is accurate and precise. It overcomes problems related to plasma sample storage and shipment, allowing TDM to be performed in a cheaper and safer manner.

Development and validation of a new UPLC-PDA method to quantify linezolid in plasma and in dried plasma spots

Linezolid is an oxazolidinone antibiotic used for the treatment of pneumonia and uncomplicated and complicated skin and soft tissues infections caused by Gram positive bacteria. It is also used as second line agent in multi-drug resistant tuberculosis. Therapeutic drug monitoring (TDM) of linezolid represents a valid tool in clinical practice to optimize therapy, especially in critically ill patients. Spreading of TDM is mainly limited by high costs shipment and lack of laboratories that offer a TDM service. To overcome these problems, the use of dried plasma spots or dried blood spots is increasing. The aim of this work was to develop and validate a new chromatographic method to analyze linezolid in plasma and in dried plasma spots and to evaluate the correlation between the two extraction methods. Linezolid extraction from plasma and from dried plasma spots was obtained using acetonitrile. Quinoxaline was used as internal standard. Analysis was performed by an ultra performance liquid chromatography (UPLC) system coupled with photo diode array (PDA) detector, at 254nm. Both analytical methods were linear (r(2)>0.999) over the calibration range of 30-0.117mg/L. Limit of quantification and limit of detection were 0.117mg/L and 0.058mg/L, respectively. Intra and inter-day precision (R.S.D.%) and accuracy (%) were <15%. Long term stability of linezolid in dried plasma spots showed absence of degradation at room temperature (20-25°C) and at 4°C, for at least one month. Linear regression analysis confirmed that the two methods of extraction have good correlation. Thus they are suited for TDM of linezolid and for pharmacokinetic studies.

A LC-MS method to quantify tenofovir urinary concentrations in treated patients.

Tenofovir disoproxil fumarate is a prodrug of tenofovir used in the treatment of HIV and HBV infections: it is the most used antiretroviral worldwide. Tenofovir is nucleotidic HIV reverse trascriptase inhibitor that showed excellent long-term efficacy and tolerability. However renal and bone complications (proximal tubulopathy, hypophosphatemia, decreased bone mineral density, and reduced creatinine clearance) limit its use. Tenofovir renal toxicity has been suggested as the consequence of drug entrapment in proximal tubular cells: measuring tenofovir urinary concentrations may be a proxy of this event and it may be used as predictor of tenofovir side effects. No method is currently available for quantifying tenofovir in this matrix: then, the aim of this work was to validate a new LC-MS method for the quantification of urinary tenofovir. Chromatographic separation was achieved with a gradient (acetonitrile and water with formic acid 0.05%) on an Atlantis 5 μm T3, 4.6 mm × 150 mm, reversed phase analytical column. Detection of tenofovir and internal standard was achieved by electrospray ionization mass spectrometry in the positive ion mode. Calibration ranged from 391 to 100,000 ng/mL. The limit of quantification was 391 ng/mL and the limit of detection was 195 ng/mL. Mean recovery of tenofovir and internal standard were consistent and stable, while matrix effect resulted low and stable. The method was tested on 35 urine samples from HIV-positive patients treated with tenofovir-based HAARTs and did not show any significant interference with antiretrovirals or other concomitantly administered drugs. All the observed concentrations in real samples fitted the calibration range, confirming the capability of this method for the use in clinical routine. Whether confirmed in ad hoc studies this method may be used for quantifying tenofovir urinary concentrations and help managing HIV-positive patients treated with tenofovir.

UPLC–MS/MS method for the simultaneous quantification of three new antiretroviral drugs, dolutegravir, elvitegravir and rilpivirine, and other thirteen antiretroviral agents plus cobicistat and ritonavir boosters in human plasma

&NA; Rilpivirine (RPV), dolutegravir (DTG) and elvitegravir (EVG) are the latest antiretroviral drugs approved for treatment of HIV infection. Currently, poor information is currently available concerning their pharmacokinetic and pharmacodynamic properties, thus making the use of therapeutic drug monitoring for these drugs not useful. This lack of information is partially due to the absence of an high‐throughput method for their simultaneous quantification together with other antiretroviral drugs. In this work, we describe the development and validation of a new UPLC–MS/MS method to quantify these drugs, together with other fourteen antiretroviral agents, in human plasma. One hundred microliters of plasma samples were added with internal standard (6,7‐Dimethyl‐ 2,3‐di(2‐pyridyl) quinoxaline), underwent a simple protein precipitation with methanol:acetonitrile (50:50 v/v) followed by sample dilution with water. Chromatographic separation was performed on a Acquity® UPLC HSS T3 column (150 mm x 2.1 mm I.D) with a particle size of 1.8 &mgr;m and compounds were detected with a tandem mass detector, monitoring two ion transitions for each drugs. The mean recovery of RPV, DTG and EVG were 101%, 87% and 112.3% respectively. Accuracy and precision inter/intra‐day were below 15% for all drugs, in accordance to Food and Drug Administration guidelines requirements. The UPLC–MS/MS method reported here could be used routinely to monitor plasma concentrations of antiviral drugs, including RPV, DTG and EVG. Graphical abstract Typical chromatogram from direct injection of a chemical mix containing all the target analytes at a concentration of 2 &mgr;g/mL. Figure. No caption available. HighlightsUseful UHPLC–MS/MS method to quantify a wide panel of antiretroviral drugs.Validated method following FDA guidelines.Fast and cheap protein precipitation protocol, suitable for clinical routine.The method has been tested on real‐life specimens with good results.

Influence of ABCB11 and HNF4α genes on daclatasvir plasma concentration: preliminary pharmacogenetic data from the Kineti-C study

Background Daclatasvir is an inhibitor of HCV non-structural 5A protein and is a P-glycoprotein substrate. Pharmacogenetics has had a great impact on previous anti-HCV therapies, particularly considering the association of IL-28B polymorphisms with dual therapy outcome. Objectives We investigated the association between daclatasvir plasma concentrations at 2 weeks and 1 month of therapy and genetic variants (SNPs) in genes encoding transporters and nuclear factors (ABCB1, ABCB11 and HNF4α). Patients and methods Allelic discrimination was achieved through real-time PCR, whereas plasma concentrations were evaluated through LC-MS/MS. Results Fifty-two patients were analysed, all enrolled in the Kineti-C study. HNF4α 975 C > G polymorphism was found to be associated with the daclatasvir plasma concentrations at 2 weeks (P = 0.009) and 1 month of therapy (P = 0.006). Linear regression analysis suggested that, at 2 weeks of therapy, age, baseline BMI and haematocrit were significant predictors of daclatasvir concentrations, whereas at 1 month of therapy ABCB111131 CC and HNF4α CG/GG genotypes were significant predictors of daclatasvir concentrations. Conclusions These are the first and preliminary results from our clinical study focusing on daclatasvir pharmacogenetics, showing that this approach could have a role in the era of new anti-HCV therapies.

Plasma and intracellular imatinib concentrations in patients with chronic myeloid leukemia.

Background: Imatinib (Gleevec, STI-571), a 2-phenylaminopyrimidine–type competitive inhibitor of Bcr-Abl kinase, is the current frontline therapy for patients with chronic myeloid leukemia, and it induces durable responses and prolonging event-free and progression-free survival. Monitoring imatinib trough plasma concentration is a simple and rapid way to determine if the drug exposure exceeds the clinical efficacy threshold (1 mcg/mL). Because the target enzyme is located within cells, adequate drug intracellular concentrations are needed to inhibit its function. Methods: Chromatographic methods were used to quantify imatinib concentrations in both plasma and peripheral blood mononuclear cells collected from adult patients with chronic myeloid leukemia at the Department of Hematology. Samples were collected at steady state, and trough concentrations (24 ± 2 hours after last drug intake) were evaluated. Associations between variables were tested using the Pearson test; results are presented as mean (±SD). Results: Thirty-five samples from 24 patients were collected; patients were mainly men (16, 66.7%), aged 60 years old (±13.1) and with a body mass index of 24.8 (±4.4). A positive and significant correlation (r = 0.203; P = 0.027) was found between imatinib plasma and intracellular concentrations. Conclusions: The observed correlation between plasma and intracellular imatinib concentrations suggests that they may be used to monitor drug exposure and treatment efficacy.

Therapeutic drug monitoring of boosted PIs in HIV-positive patients: undetectable plasma concentrations and risk of virological failure

Background Therapeutic drug monitoring (TDM) of antiretroviral drugs is performed in selected HIV-positive patients. The aim of this study was to estimate the prevalence of undetectable plasma concentrations of ritonavir and boosted PIs and to evaluate the association between those and the 48 week risk of virological failure. Methods A TDM registry study and a retrospective follow-up study were conducted. Plasma concentrations were measured through validated methods. According to PI and ritonavir concentrations, patients were stratified as adherent, partially non-adherent or non-adherent. Virological outcome was evaluated 48 weeks afterwards. Results The TDM registry study included 2468 samples collected from 723 patients (68.1% male, median age 43.5 years). Eighty-seven samples (3.5%, 74 patients) and 68 samples (2.8%, 52 patients) were in the partially non-adherent and non-adherent groups, respectively; more patients on atazanavir/ritonavir (7.9%) versus darunavir/ritonavir (2% twice daily and 1.9% once daily) and lopinavir/ritonavir (1.5%; P  <   0.001) were observed in the partially non-adherent group. Two hundred and ninety patients were included in the follow-up study (64.1% male, median age 40 years). Patients in the adherent group had a higher chance of viral control [81.9% (167/204)] versus the partially non-adherent group and the non-adherent group [71.7% (33/46) and 53.1% (17/32), respectively; P  =   0.001]. Based on multivariate analysis, baseline HIV RNA >50 copies/mL ( P  <   0.001), genotypic susceptibility score ≤2 ( P  =   0.001), lower nadir CD4 cell count ( P  =   0.003) and not being in the adherent group ( P  =   0.029) were independent predictors of HIV RNA >50 copies/mL at 48 weeks. Conclusions The measurement of PI and ritonavir plasma levels can uncover incomplete compliance with treatment; TDM may represent a useful tool for identifying patients in need of adherence-promoting interventions.

Pharmacokinetics of dolutegravir and rilpivirine in combination with simeprevir and sofosbuvir in HIV/hepatitis C virus-coinfected patients with liver cirrhosis

Objectives: To evaluate the plasma trough concentrations (Ctrough) of dolutegravir and rilpivirine used in combination with simeprevir and sofosbuvir in HIV/hepatitis C virus (HCV)-coinfected patients with liver cirrhosis. Virological efficacy and safety of both ART and anti-HCV therapy were assessed. Patients and methods: A prospective observational study in HIV/HCV-coinfected patients with liver cirrhosis on ART with dolutegravir plus rilpivirine and treated with simeprevir plus sofosbuvir (±ribavirin) was conducted. Dolutegravir, rilpivirine, GS-331007 (sofosbuvir metabolite) and simeprevir Ctrough were evaluated with a validated HPLC method at anti-HCV treatment baseline and weeks 2 and 4. Geometric means were calculated to summarize Ctrough values. Results: Twelve patients were evaluated: 75% were males and the median (IQR) age was 53 (53–55) years. All patients were Child–Pugh stage A, except one who was stage B. The geometric mean (95% CI) of Ctrough of rilpivirine and dolutegravir did not change between baseline and week 4 (P = 0.654 and P = 0.268, respectively), with corresponding overall values of 135 (102–177) and 1357 (970–1897) ng/mL. The overall geometric mean (95% CI) of GS-331007 and simeprevir Ctrough was 370 (268–512) and 2537 (1569–4101) ng/mL, respectively, without significant variation between weeks 2 and 4 (P = 0.643 and P = 0.179, respectively). All patients completed anti-HCV treatment, achieving sustained virological response. All but two patients maintained undetectable HIV-RNA up to post-treatment week 24. Conclusions: Dolutegravir and rilpivirine Ctrough appeared not to be affected by concomitant treatment with simeprevir plus sofosbuvir in these HIV/HCV-coinfected patients with liver cirrhosis, supporting the use of this antiretroviral regimen in this setting.

Vitamin D pathway genetic variants are able to influence sofosbuvir and its main metabolite pharmacokinetics in HCV mono-infected patients

Vitamin D levels and genetic variants were associated with drug outcome/toxicity and concentrations. The plasma exposure of GS-331007, the main sofosbuvir metabolite, has been related to SVR. We evaluated the impact of polymorphisms in genes (CYP27B1, CYP24A1, VDBP and VDR) related to vitamin D pathway on sofosbuvir and GS-331007 plasma levels in HCV mono-infected patients at one month of treatment. Polymorphisms were investigated through real-time PCR; drug plasma quantification was performed through a UHPLC-MS/MS method. GS-331007 levels were associated with CYP24A1rs2248359 and VDRCdx2 variants in all the analyzed patients and linear regression analysis showed that sex, body mass index, HCV genotype, baseline estimated glomerular filtration rate, VDRCdx2AG/GG and CYP27B1-1260TT genotypes significantly predict concentrations. We performed sub-analyses considering the HCV genotype and the concomitant drug, identifying polymorphisms associated with GS-331007 concentrations. This is the first study focusing on vitamin D pathway gene variants and DAAs concentrations, but further studies are required.