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1.
Br J Cancer ; 130(1): 135-142, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-37938348

RESUMO

BACKGROUND: Resistance to osimertinib in advanced EGFR-mutated non-small cell lung cancer (NSCLC) constitutes a significant challenge for clinicians either in terms of molecular diagnosis and subsequent therapeutic implications. METHODS: This is a prospective single-centre study with the primary objective of characterising resistance mechanisms to osimertinib in advanced EGFR-mutated NSCLC patients treated both in first- and in second-line. Next-Generation Sequencing analysis was conducted on paired tissue biopsies and plasma samples. A concordance analysis between tissue and plasma was performed. RESULTS: Sixty-five advanced EGFR-mutated NSCLC patients treated with osimertinib in first- (n = 56) or in second-line (n = 9) were included. We managed to perform tissue and liquid biopsies in 65.5% and 89.7% of patients who experienced osimertinib progression, respectively. Acquired resistance mechanisms were identified in 80% of 25 patients with post-progression samples, with MET amplification (n = 8), EGFR C797S (n = 3), and SCLC transformation (n = 2) the most frequently identified. The mean concordance rates between tissue and plasma for the EGFR activating mutation and for the molecular resistance mechanisms were 87.5% and 22.7%, respectively. CONCLUSIONS: Resistance to osimertinib demonstrated to be highly heterogeneous, with MET amplification the main mechanism. Plasma genotyping is a relevant complementary tool which might integrate tissue analysis for the study of resistance mechanisms.


Assuntos
Acrilamidas , Carcinoma Pulmonar de Células não Pequenas , Indóis , Neoplasias Pulmonares , Pirimidinas , Humanos , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Estudos Prospectivos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Receptores ErbB/genética , Genótipo , Mutação , Resistencia a Medicamentos Antineoplásicos/genética , Inibidores de Proteínas Quinases/uso terapêutico , Inibidores de Proteínas Quinases/farmacologia , Compostos de Anilina/uso terapêutico , Biópsia Líquida
2.
ESMO Open ; 7(6): 100634, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36493602

RESUMO

BACKGROUND: The Meet-URO score allowed a more accurate prognostication than the International Metastatic RCC Database Consortium (IMDC) for patients with pre-treated metastatic renal cell carcinoma (mRCC) by adding the pre-treatment neutrophil-to-lymphocyte ratio and presence of bone metastases. MATERIALS AND METHODS: A post hoc analysis was carried out to validate the Meet-URO score on the overall survival (OS) of patients with IMDC intermediate-poor-risk mRCC treated with first-line nivolumab plus ipilimumab within the prospective Italian Expanded Access Programme (EAP). We additionally considered progression-free survival (PFS) and disease response rates. Harrell's c-index was calculated to compare the accuracy of survival prediction. RESULTS: Overall the EAP included 306 patients, with a median follow-up of 12.2 months, median OS was not reached, 1-year OS was 66.8% and median PFS was 7.9 months. By univariable analysis, both the IMDC score and the two additional variables of the Meet-URO score were associated with either OS or PFS (P < 0.001 for all comparisons). The four Meet-URO risk groups (G) had 1-year OS of 92%, 72%, 50% and 21% for G2 (29.1% of patients), G3 (28.8%), G4 (33.0%) and G5 (9.1%), respectively. OS was significantly shorter in each consecutive G (P = 0.001 for G3, P < 0.001 for both G4 and G5 compared to G2). Similarly, Meet-URO Gs 2-5 showed decreasing median PFS and response rates. The Meet-URO score showed the highest c-index for both OS (0.73) and PFS (0.67). Limitations include the post hoc nature of this analysis and the lack of a comparative arm to assess predictive value. CONCLUSION: The Meet-URO score appeared to show better prognostic classification than the IMDC alone in patients with mRCC at IMDC intermediate-poor risk treated with first-line nivolumab and ipilimumab.


Assuntos
Carcinoma de Células Renais , Neoplasias Renais , Humanos , Carcinoma de Células Renais/tratamento farmacológico , Carcinoma de Células Renais/secundário , Nivolumabe/farmacologia , Nivolumabe/uso terapêutico , Ipilimumab/farmacologia , Ipilimumab/uso terapêutico , Neoplasias Renais/tratamento farmacológico , Neoplasias Renais/patologia , Estudos Prospectivos , Estudos Retrospectivos
3.
Ann Oncol ; 33(11): 1179-1185, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35926813

RESUMO

BACKGROUND: Cisplatin-based chemotherapy is the most recommended treatment for metastatic urothelial cancer (mUC). However, about 50% of patients are considered to be cisplatin ineligible. Anti-programmed cell death protein 1/programmed death-ligand 1 (PD-L1) therapies have, nevertheless, increased the options available to clinicians and are especially valuable for treating these patients. This study therefore tested the activity and safety of avelumab as first-line therapy for mUC. PATIENTS AND METHODS: Patients with mUC who were ineligible for cisplatin-based chemotherapy were screened centrally for PD-L1 expression and only those with a tumour proportion score ≥ 5% were enrolled in the trial. The primary endpoint was 1-year overall survival (OS), and the secondary endpoints were median OS, median progression-free survival, overall response rate, duration of the response, safety and tolerability. All the survival rates were estimated with the Kaplan-Meier product-limit methodology and compared across groups using the log-rank test. RESULTS: A total of 198 patients were screened, with 71 (35.9%) whose PD-L1 expression was ≥5% enrolled in the study. The median age was 75 years, bladder cancer was the primary tumour in 73.2% of cases and 25.3% had liver metastases. The main reasons for the cisplatin ineligibility were a low rate of creatinine clearance (<60 ml/min), present in 70.4% of patients, and an Eastern Cooperative Oncology Group performance status of 2, which affected 31%. The median OS was 10.0 months (95% confidence interval 5.5-14.5 months) and 43% of patients were alive at 1 year. A complete response was achieved in 8.5% of cases, and 15.5% had a partial response. Adverse any-grade and high-grade events occurred in 49.3% and 8.5% of patients, respectively. A grade 3 infusion reaction was the only high-grade treatment-related adverse event. No treatment-related deaths were reported. CONCLUSIONS: This ARIES trial confirmed the activity and safety of avelumab for treating mUC, adding a new therapy option to the armamentarium of checkpoint inhibitors already approved for platinum-ineligible, locally advanced/mUC.


Assuntos
Anticorpos Monoclonais Humanizados , Carcinoma de Células de Transição , Neoplasias da Bexiga Urinária , Idoso , Humanos , Antígeno B7-H1 , Carcinoma de Células de Transição/tratamento farmacológico , Cisplatino , Neoplasias da Bexiga Urinária/tratamento farmacológico , Anticorpos Monoclonais Humanizados/efeitos adversos
5.
ESMO Open ; 6(2): 100078, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33735802

RESUMO

BACKGROUND: To stratify the prognosis of patients with programmed cell death-ligand 1 (PD-L1) ≥ 50% advanced non-small-cell lung cancer (aNSCLC) treated with first-line immunotherapy. METHODS: Baseline clinical prognostic factors, the neutrophil-to-lymphocyte ratio (NLR), PD-L1 tumour cell expression level, lactate dehydrogenase (LDH) and their combination were investigated by a retrospective analysis of 784 patients divided between statistically powered training (n = 201) and validation (n = 583) cohorts. Cut-offs were explored by receiver operating characteristic (ROC) curves and a risk model built with validated independent factors by multivariate analysis. RESULTS: NLR < 4 was a significant prognostic factor in both cohorts (P < 0.001). It represented 53% of patients in the validation cohort, with 1-year overall survival (OS) of 76.6% versus 44.8% with NLR > 4, in the validation series. The addition of PD-L1 ≥ 80% (21% of patients) or LDH < 252 U/l (25%) to NLR < 4 did not result in better 1-year OS (of 72.6% and 74.1%, respectively, in the validation cohort). Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 2 [P < 0.001, hazard ratio (HR) 2.04], pretreatment steroids (P < 0.001, HR 1.67) and NLR < 4 (P < 0.001, HR 2.29) resulted in independent prognostic factors. A risk model with these three factors, namely, the lung immuno-oncology prognostic score (LIPS)-3, accurately stratified three OS risk-validated categories of patients: favourable (0 risk factors, 40%, 1-year OS of 78.2% in the whole series), intermediate (1 or 2 risk factors, 54%, 1-year OS 53.8%) and poor (>2 risk factors, 5%, 1-year OS 10.7%) prognosis. CONCLUSIONS: We advocate the use of LIPS-3 as an easy-to-assess and inexpensive adjuvant prognostic tool for patients with PD-L1 ≥ 50% aNSCLC.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Anticorpos Monoclonais Humanizados , Antígeno B7-H1 , Carcinoma Pulmonar de Células não Pequenas/diagnóstico , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Humanos , Pulmão , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/tratamento farmacológico , Prognóstico , Estudos Retrospectivos
6.
Lung Cancer ; 148: 1-11, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32768804

RESUMO

INTRODUCTION: Upfront criteria to foresee immune checkpoint inhibitors (ICIs) efficacy are far from being identified. Thus, we integrated blood descriptors of pro-inflammatory/immunosuppressive or effective anti-tumor response to non-invasively define predictive immune profiles in ICI-treated advanced non-small cell lung cancer (NSCLC). METHODS: Peripheral blood (PB) was prospectively collected at baseline from 109 consecutive NSCLC patients undergoing ICIs as first or more line treatment. Soluble PD-L1 (sPD-L1) (immunoassay), CD8+PD-1+ and NK (FACS) cells were assessed and interlaced to generate an Immune effector Score (IeffS). Lung Immune Prognostic Index (LIPI) was computed by LDH levels and derived Neutrophil-to-Lymphocyte Ratio (dNLR). All these parameters were correlated with survival outcome and treatment response. RESULTS: High sPD-L1 and low CD8+PD-1+ and NK number had negative impact on PFS (P < 0.001), OS (P < 0.01) and ICI-response (P < 0.05). Thus, sPD-L1high, CD8+PD-1+low and NKlow were considered as risk factors encompassing IeffS, whose prognostic power outperformed that of individual features and slightly exceeded that of LIPI. Accordingly, the absence of these risk factors portrayed a favorable IeffS characterizing patients with significantly (P < 0.001) prolonged PFS (median NR vs 2.3 months) and OS (median NR vs 4.1) and greater benefit from ICIs (P < 0.01). We then combined each risk parameter composing IeffS and LIPI (LDHhigh, dNLRhigh), thus defining three distinct prognostic classes. A remarkable impact of IeffS-LIPI integration was documented on survival outcome (PFS, HR = 4.61; 95%CI = 2.32-9.18; P < 0.001; OS, HR=4.03; 95%CI=1.91-8.67; P < 0.001) and ICI-response (AUC=0.90, 95%CI=0.81-0.97, P < 0.001). CONCLUSION: Composite risk models based on blood parameters featuring the tumor-host interaction might provide accurate prognostic scores able to predict ICI benefit in NSCLC patients.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Antígeno B7-H1 , Linfócitos T CD8-Positivos , Carcinoma Pulmonar de Células não Pequenas/terapia , Humanos , Imunoterapia , Células Matadoras Naturais , Neoplasias Pulmonares/terapia , Prognóstico , Receptor de Morte Celular Programada 1
9.
Ann Oncol ; 28(11): 2747-2753, 2017 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-28945839

RESUMO

Background: Prognostic scores have been developed to estimate the risk of recurrence and the probability of survival after nephrectomy for renal cell carcinoma (RCC). The use of these tools, despite being helpful to plan a customized schedule of follow-up, to the patient's tailored counselling and to select individuals who could potentially benefit from adjuvant treatment, currently is not routine, due to their relative complexity and to the lack of histological data (i.e. necrosis). Patients and methods: We developed a simple score called GRade, Age, Nodes and Tumor (GRANT) based on four easily obtained parameters: Fuhrman grade, age, pathological nodal status and pathological tumor size. Patients with 0 or 1 factor are classified as favorable risk, whereas patients with two or more risk factors as unfavorable risk. The large population of RCC patients from the ASSURE adjuvant trial was used as independent dataset for this external validation, to investigate the prognostic value of the new score in terms of disease-free survival and overall survival and to evaluate its possible application as predictive tool. Statistical analyses were carried out by the Department of Biostatistics & Computational Biology, Dana-Farber Cancer Institute (Boston, USA) for the ASSURE trial patients' population. Results: The performance of the new model is similar to that of the already validated score systems, but its strength, compared with the others already available, is the ease and clarity of its calculation, with great speed of use during the clinical practice. Limitations are the use of the Fuhrman nuclear grade, not valid for rare histologies, and the TNM classification modifications over time. Conclusion: The GRANT score demonstrated its potential usefulness for clinical practice. ClinicalTrials.gov Identifier for the ASSURE trial: NCT00326898.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma de Células Renais/mortalidade , Neoplasias Renais/mortalidade , Recidiva Local de Neoplasia/mortalidade , Carcinoma de Células Renais/tratamento farmacológico , Carcinoma de Células Renais/patologia , Feminino , Seguimentos , Indicadores Básicos de Saúde , Humanos , Indóis/administração & dosagem , Neoplasias Renais/tratamento farmacológico , Neoplasias Renais/patologia , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/patologia , Estadiamento de Neoplasias , Niacinamida/administração & dosagem , Niacinamida/análogos & derivados , Compostos de Fenilureia/administração & dosagem , Valor Preditivo dos Testes , Prognóstico , Estudos Prospectivos , Pirróis/administração & dosagem , Fatores de Risco , Sorafenibe , Sunitinibe , Taxa de Sobrevida
10.
Target Oncol ; 10(2): 277-86, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25230695

RESUMO

The aim of this study was to explore the efficacy and toxicities of a combined regimen of bevacizumab plus immunotherapy and chemotherapy (BIC) and the circulating T regulatory cells (Treg) in metastatic renal cell cancer (mRCC). Nephrectomized mRCC patients were enrolled into a multicenter single-arm dose-finding study with five escalated dose levels of chemotherapy with intravenous gemcitabine and 5-fluorouracil associated with fixed intravenous doses of bevacizumab, subcutaneous low doses of interleukin-2, and interferon-α-2a. An expanded cohort (phase II study) was treated at the recommended dose for additional safety and efficacy information according to minimax Simon two-stage design. Blood samples for Treg were collected and evaluated by fluorescence-activated cell sorting (FACS) analysis on cycle 1. Fifty-one patients were entered to receive one of five dose levels. Median age was 58 years (male 67 %, pretreated 49 %): 15 patients were low risk according to Memorial Sloan-Kettering Cancer Center (MSKCC) criteria, while 27 and nine were respectively intermediate- and high-risk patients. More frequent grade 3 and 4 toxicities included nonfebrile neutropenia, thrombocytopenia, and fever. Among patients evaluable for response (49), 29.5 % had partial response and 37 % stable disease. Overall median time to progression and median overall survival were 8.8 and 22.67 months, respectively. We observed a rapid increase in the percentage of Treg after immunotherapy and a reduction after bevacizumab only in patient who obtained a partial response or stable disease. The BIC was feasible, well tolerated, and shown interesting activity. Further studies are needed to explore if Treg could have a role in clinical response in mRCC treated with bevacizumab.


Assuntos
Inibidores da Angiogênese/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Bevacizumab/administração & dosagem , Carcinoma de Células Renais/tratamento farmacológico , Imunoterapia/métodos , Neoplasias Renais/tratamento farmacológico , Linfócitos T Reguladores/efeitos dos fármacos , Administração Intravenosa , Adulto , Idoso , Idoso de 80 Anos ou mais , Inibidores da Angiogênese/efeitos adversos , Antimetabólitos Antineoplásicos/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Bevacizumab/efeitos adversos , Carcinoma de Células Renais/imunologia , Carcinoma de Células Renais/mortalidade , Carcinoma de Células Renais/patologia , Separação Celular/métodos , Quimioterapia Adjuvante , Desoxicitidina/administração & dosagem , Desoxicitidina/análogos & derivados , Progressão da Doença , Intervalo Livre de Doença , Feminino , Citometria de Fluxo , Fluoruracila/administração & dosagem , Humanos , Imunoterapia/efeitos adversos , Interferon alfa-2 , Interferon-alfa/administração & dosagem , Interleucina-2/administração & dosagem , Itália , Estimativa de Kaplan-Meier , Neoplasias Renais/imunologia , Neoplasias Renais/mortalidade , Neoplasias Renais/patologia , Masculino , Pessoa de Meia-Idade , Nefrectomia , Proteínas Recombinantes/administração & dosagem , Linfócitos T Reguladores/imunologia , Fatores de Tempo , Resultado do Tratamento , Gencitabina
11.
Ann Oncol ; 23(9): 2409-2414, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22357254

RESUMO

BACKGROUND: To analyze a multi-institutional series of type C thymic carcinomas (TCs) (including neuroendocrine tumors), focusing on the expression and mutations of c-KIT. MATERIALS AND METHODS: Immunohistochemical expression of c-KIT/CD117, p63, CD5 and neuroendocrine markers, as well as mutational analysis of c-KIT exons 9, 11, 13, 14, 17 by direct sequencing of 48 cases of TCs. Immunohistochemical and molecular data were statistically crossed with clinicopathological features. RESULTS: Overall, 29 tumors (60%) expressed CD117, 69% were positive for CD5 and 85% (41 cases) for p63. Neuroendocrine markers stained all six atypical carcinoids and five poorly-differentiated thymic squamous cell carcinomas. Overall, six CD117-positive cases (12.5%) showed c-KIT mutation. No mutation was detected in CD117-negative tumors and carcinoids. All the mutations were found in poorly-differentiated thymic squamous cell carcinomas expressing CD117, CD5, p63 and lacking neuroendocrine markers (6 of 12 cases with these features). Mutations involved exon 11 (four cases: V559A, L576P, Y553N, W557R), exon 9 (E490K) and exon 17 (D820E). CONCLUSIONS: All TCs need an immunohistochemical screening with CD117, while c-KIT mutation analysis is mandatory only in CD117-positive cases, particularly when coexpressing CD5 and p63, lacking neuroendocrine differentiation. The finding of c-KIT mutation can predict efficacy with different c-KIT inhibitors.


Assuntos
Tumor Carcinoide/genética , Carcinoma de Células Escamosas/genética , Mutação de Sentido Incorreto , Proteínas Proto-Oncogênicas c-kit/genética , Timoma/genética , Neoplasias do Timo/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Benzamidas , Benzenossulfonatos/farmacologia , Benzenossulfonatos/uso terapêutico , Antígenos CD5/metabolismo , Tumor Carcinoide/tratamento farmacológico , Carcinoma de Células Escamosas/tratamento farmacológico , Análise Mutacional de DNA , Ativação Enzimática/genética , Feminino , Estudos de Associação Genética , Humanos , Mesilato de Imatinib , Indóis/farmacologia , Indóis/uso terapêutico , Masculino , Pessoa de Meia-Idade , Niacinamida/análogos & derivados , Compostos de Fenilureia , Piperazinas/farmacologia , Piperazinas/uso terapêutico , Proteínas Proto-Oncogênicas c-kit/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-kit/metabolismo , Piridinas/farmacologia , Piridinas/uso terapêutico , Pirimidinas/farmacologia , Pirimidinas/uso terapêutico , Pirróis/farmacologia , Pirróis/uso terapêutico , Estudos Retrospectivos , Sorafenibe , Sunitinibe , Timoma/tratamento farmacológico , Timoma/metabolismo , Neoplasias do Timo/tratamento farmacológico , Neoplasias do Timo/metabolismo , Fatores de Transcrição/metabolismo , Resultado do Tratamento , Proteínas Supressoras de Tumor/metabolismo
12.
Anal Chim Acta ; 598(1): 119-27, 2007 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-17693315

RESUMO

The resinous materials from the interior surfaces of two Roman and one Iberian amphora were studied with Fourier transform infrared (FTIR) spectroscopy. The results were then compared with those obtained by synchrotron radiation-FTIR, scanning electron microscopy (SEM), and gas chromatography-mass spectrometry (GC-MS). The FTIR spectra obtained by the technique of KBr micropellets, prepared directly with the materials scraped from the amphora without any further sample preparation, provided enough information to establish their diterpenoic nature, and even to differentiate between the two main materials employed for waterproofing purposes, pitch and wood tar. Methyl dehydroabietic acid (DHAM) is the main chemical marker that allows a distinction to be made between these two materials. Pitch and wood tar were prepared in the laboratory heating pine resin and resinous pine wood, respectively. These resinous waterproofing materials were compared with the coatings extracted from the amphorae. The samples whose direct FTIR spectra showed a signal at approximately 1740 cm(-1), attributed to a carbonyl group of methyl ester, presented as well a peak of DHAM in the GC-MS chromatogram of the neutral fraction of their extract. Samples without this signal in their spectra did not present DHAM in their chromatogram. This work studies, for the first time, waterproofing of an amphora attributed to the Iberian culture.

13.
J Dairy Sci ; 85(5): 1031-8, 2002 May.
Artigo em Inglês | MEDLINE | ID: mdl-12086036

RESUMO

The objective of this research was to investigate the effect of a cyanobacterial (Spirulina platensis) biomass on the microflora of a probiotic fermented dairy product during storage at two temperatures. Spirulina-enriched and control (plain) fermented acidophilus-bifidus-thermophilus (ABT) milks were produced using a fast fermentation starter culture (ABT-4) as the source of Lactobacillus acidophilus (A), bifidobacteria (B), and Streptococcus thermophilus (T). Incubation took 6 h at 40 degrees C. As for the cyanobacterial product, the S. platensis biomass was added to the process milk during stirring at pH 4.5 to 4.6. Thereafter, the ABT-type fermented milks were cooled to 25 degrees C in ice water, filled into sterile, tightly capped centrifuge tubes, further cooled at 4 degrees C for 24 h, and then stored either at 15 degrees C for 18 d or at 4 degrees C for 42 d. Microbiological analyses and acidity measurements were performed at regular intervals. Our results showed that the counts of the starter organisms were satisfactory during the entire storage period at both temperatures applied in this research. The S. platensis biomass had a beneficial effect on the survival of ABT starter bacteria regardless of storage temperature. Postacidification was observed at 15 degrees C, whereas pH remained stable during refrigerated storage at 4 degrees C. The abundance of bioactive substances in S. platensis is of great importance from a nutritional point of view because thus the cyanobacterial biomass provides a new opportunity for the manufacture of functional dairy foods.


Assuntos
Proteínas de Bactérias/fisiologia , Fermentação , Lactobacillus acidophilus/crescimento & desenvolvimento , Leite/microbiologia , Streptococcus/crescimento & desenvolvimento , Animais , Biomassa , Temperatura Baixa , Contagem de Colônia Microbiana , Conservação de Alimentos , Concentração de Íons de Hidrogênio , Spirulina
14.
Talanta ; 45(5): 817-27, 1998 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18967066

RESUMO

The dissociation constants of representative loop (furosemide), thiazide (chlorthiazide and trichlormethiazide) and potassium sparing (amiloride) diuretics in 10, 30, 40, 50 and 70% (w/w) acetonitrile-water mixtures at 298.15 K were determined, in accordance with IUPAC procedures. The variation in pK(a) values over the whole composition range can be explained by preferential solvation and the structural features in acetonitrile-water mixtures. Correlations between pK(a) values and various bulk and solvatochromic properties of the solvents were calculated. The linear solvation energy relationship (LSER) method was applied. The resulting equations allowed us to calculate pK(a) values for the diuretics studied in any acetonitrile-water mixture up to 70% (w/w) and should help to clarify the acid-base behaviour of diuretics in the widely-used acetonitrile-water mixed solvents.

15.
Acta Chem Scand (Cph) ; 51(11): 1078-84, 1997 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9394436

RESUMO

The dissociation pK values of the representative loop diuretics furosemide, bumetanide and ethacrynic acid in 10, 30, 40, 50 and 70% (w/w) acetonitrile-water mixtures at 298.15 K were determined, according to the rules and procedures endorsed by IUPAC. The variation in pK values over the whole composition range studied can be explained by tacking into account the preferential solvation of ionizable substances in acetonitrile-water mixtures. With a view to determining the pK values of the loop diuretics studied in any of the binary solvent acetonitrile-water mixtures, correlations of pK values and different bulk properties of the solvent were examined, and the linear solvation energy relationships method, LSER, has been applied. The pK values were then correlated with the pi*, alpha and beta solvatochromic parameters of acetonitrile-water mixtures. The resulting equations allowed us to calculate pK values for the loop diuretics in any acetonitrile-water mixture up to 70% (w/w) acetonitrile.


Assuntos
Bumetanida/química , Diuréticos/química , Ácido Etacrínico/química , Furosemida/química , Acetonitrilas/química , Estrutura Molecular , Potenciometria , Água/química
16.
Talanta ; 41(5): 825-31, 1994 May.
Artigo em Inglês | MEDLINE | ID: mdl-18966005

RESUMO

Reference value standards, pH(s) in 10% (w/w) acetonitrile-water solvent mixtures for 11 reference buffer solutions have been determined from reversible emf measurements of the cell Pt/Ag/AgCl/standard buffer + KCl, in acetonitrile-water/glass electrode, at 298.15 K. Values of ionization constants, required for above calculations, have been determined from reversible emf measurements of the cell Pt/Ag/AgCl/HA + A + KCl, in acetonitrile-water/glass electrode, in the same solvent composition and temperature.

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