RESUMO
BACKGROUND: Venlafaxine (VEN), a well accepted anti-depressant, is metabolized through the cytochrome P 450 (CYP) 2D6 isozyme to form O-desmethyvenlafaxine (ODV). Due to the involvement of CYP2D6, the formation of ODV is influenced by genetic polymorphism. We used standard tools of assessment to explore the phenotypic distribution in a retrospective manner using the pharmacokinetic (PK) data of VEN and ODV obtained from several bioavailability/bioequivalence (BA/BE) studies in healthy subjects using the reference formulation. METHODS: Four single oral dose, open-label, randomized crossover BA/BE studies of VEN (doses: 37.5-150 mg) were performed in 141 healthy subjects. Plasma samples were collected over a period 72 h post VEN administration. The samples were analyzed for VEN and ODV using a validated LC/MS/MS assay with a limit of quantification 2.073 ng/mL for VEN and 3.973 ng/mL for ODV. PK parameters (C(max), T(max), AUC (0-t), AUC(0-infinity), t(1/2)) were computed using the noncompartmental approach. AUC metabolic ratios of VEN/ODV and ODV/VEN were computed for all subjects and were subjected to normality test procedures to tease out phenotypic distribution. RESULTS: ODV/VEN and VEN/ODV AUC metabolic ratios were evaluated for standard normal distribution and outliers to determine phenotypic distribution. Use of the VEN/ODV AUC metabolic ratio, arranged in a rank order, resulted in a distribution that distinguished poor metabolizers (PM) and extensive metabolizers (EM). The application of the ODV/VEN AUC metabolic ratio showed a unique distribution that distinguished ultra metabolizers (UM) and extensive metabolizers. By using both metabolic ratios, 141 healthy subjects were classified as follows: PMs = 18, EMs = 118, UMs = 5. Regardless of the formulation or dose size used, the plasma concentration-time profiles for both VEN and ODV were distinct amongst the three phenotypes identified in this work. CONCLUSIONS: The use of VEN/ODV and ODV/VEN AUC metabolic ratios suggested quantitative differences. The data support the use of ODV/VEN but not VEN/ODV metabolic ratio for the identification of UM phenotypes of VEN. The derived metabolic ratios of ODV/VEN from this work were in line with other studies that used both phenotypic and genotypic correlation strategies for VEN.
Assuntos
Cicloexanóis/metabolismo , Cicloexanóis/farmacocinética , Citocromo P-450 CYP2D6/genética , Administração Oral , Adulto , Antidepressivos de Segunda Geração/metabolismo , Antidepressivos de Segunda Geração/farmacocinética , Área Sob a Curva , Disponibilidade Biológica , Estudos Cross-Over , Cicloexanóis/administração & dosagem , Succinato de Desvenlafaxina , Feminino , Genótipo , Humanos , Índia , Masculino , Fenótipo , Estudos Retrospectivos , Inibidores Seletivos de Recaptação de Serotonina/metabolismo , Inibidores Seletivos de Recaptação de Serotonina/farmacocinética , Equivalência Terapêutica , Cloridrato de VenlafaxinaRESUMO
BACKGROUND: Coronary artery disease (CAD) occurs at younger age in India but only a limited number of studies have evaluated risk factors and management status. This is a multisite observational registry to assess risk factors and treatment patterns in young patients presenting with acute coronary syndrome (ACS) and stable ischemic heart disease (IHD). METHODS: We recruited 997 young patients (men <55, women <65y) presenting with ACS or stable IHD successively at 22 centers across India. Details of baseline risk factors and management status were obtained. Descriptive statistics are reported. RESULTS: Mean age of participants was 49.1±8y, 72% were men and 68% had ACS. Family history of CAD was in 50%, diabetes 44%, hypertension 49%, history of dyslipidemia 11%, smoking/tobacco use 39%, and sedentary habits in 20%. 1.3% had "possible familial hypercholesterolemia". Metabolic risk factors (high BMI, diabetes and hypertension) were significantly greater in women (p<0.01). Women were older at diagnosis of CAD and presented more often with non-ST elevation ACS. In the study cohort antiplatelet use was in 85%, beta-blockers 38%, statins 63% and ACE inhibitors/ARBs in 41% while in ACS patients it was 80.5%, 54.6%, 80.8% and 40.8%, respectively. 35.9% patients underwent percutaneous coronary intervention while coronary bypass surgery was performed in 10.4%. CONCLUSIONS: Conventional risk factors including family history continue to play a pivotal role in premature CAD in Indians. Women have more of metabolic risk factors, present at a later age and have non-ST elevation ACS more often. There is a need to focus on improving use of evidence-based drug therapies and interventions.
Assuntos
Doença da Artéria Coronariana/epidemiologia , Sistema de Registros , Idade de Início , Angiografia Coronária , Doença da Artéria Coronariana/diagnóstico , Feminino , Humanos , Incidência , Índia/epidemiologia , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos , Fatores de Risco , Taxa de Sobrevida/tendênciasRESUMO
A simple, sensitive, precise and accurate method for simultaneous estimation of metformin and sitagliptin from human plasma was developed and validated. Samples extracted from plasma using acetonitrile were separated on an SCX column and estimated using API 4000 Mass Spectrometer in the positive atmospheric pressure ionization mode (Turboionspray) by following multiple reaction monitoring transitions for both parent and daughter ions. A linear calibration plot was achieved for both the analytes in the concentration ranges of 10-2,206 ng/mL (for metformin) and 3-800.5 ng/mL (for sitagliptin) prepared in K2EDTA pooled plasma. Mean recovery for metformin was 92% and for sitagliptin was 104.5%. It is a fully validated method and successfully applied for estimation of these drug molecules during biostudies.
Assuntos
Cromatografia Líquida/métodos , Metformina/sangue , Fosfato de Sitagliptina/sangue , Espectrometria de Massas em Tandem/métodos , Estabilidade de Medicamentos , Humanos , Metformina/química , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Fosfato de Sitagliptina/química , Equivalência TerapêuticaRESUMO
BACKGROUND: Fluoxetine, belonging to the class of selective serotonin uptake inhibitors, has been extensively used for the treatment of depression and other psychiatry related disorders. Fluoxetine (CAS 59333-67-4) is a substrate of polymorphic cytochrome P450 2D6 isozyme (CYP2D6) leading to the formation of norfluoxetine (CAS 83891-03-06), which is not only active but long lived than the parent in the systemic circulation. Since the parent and metabolite levels are important from a therapeutic perspective, knowledge of phenotypic distribution of the population may be an important consideration. OBJECTIVE: The aim of the work was to retrospectively evaluate the pharmacokinetic data of fluoxetine and norfluoxetine from several bioavailability/bioequivalence (BA/BE) studies to identify the poor metabolizer (PM) phenotypes from the unsuspected healthy subjects across varied protocol designs, dose sizes and differing formulations. METHODS: The pharmacokinetic data of fluoxetine and norfluoxetine were gathered from several BA/BE studies conducted at clinical facilities located at Bangalore and Chennai, India. The BA/BE studies involved open label, two-way randomized crossover designs with two periods and two treatments (reference and test). Blood samples were collected for at least 672 h after fluoxetine dosing and the plasma was analyzed using validated tandem liquid chromatography mass spectrometric assay to determine fluoxetine and norfluoxetine levels. Standard pharmacokinetic parameters were computed using noncompartmental methods. For the purpose of this paper, retrospective evaluation of pharmnacokinetic data from only the reference formulation was considered. The AUC ratio of fluoxetine/norfluoxetine was computed. The individual fluoxetine/norfluoxetine AUC(0-infinity), ratios were plotted in increasing rank order and using outlier test ('T' procedure at 5% level of significance) the subjects were categorized as extensive metabolizer (EM) and PM phenotypes. The unequivocal confirmation of PM phenotypes was obtained by performing linear regression analysis of fluoxetine vs norfluoxetine AUC(0-infinity) values. RESULTS: Each study was evaluated for the distribution of EM and PM phenotypes of fluoxetine. There were 144 subjects evaluable from four studies, 89.6% (129 out of 144) of which could be categorised as EMs and 10.4% (15 out of 144) as PMs of fluoxetine. The pharmacokinetic parameters were quite distinct between the two phenotypes: (1) PM phenotypes showed much higher exposure (approximately 2.3-fold increase in AUC(0-infinity) and much slower elimination (almost 2-fold increase in elimination half-life) for fluoxetine as compared to EM phenotypes; (2) PM phenotypes showed approximately 0.5-fold lower exposure of norfluoxetine as compared to the EM counter parts; (3) There was no change (approximately 1.2-fold) in the elimination half life of norfluoxetine in EM and PM phenotypes. CONCLUSIONS: Retrospective evaluation of fluoxetine and norfluoxetine pharmacokinetic data demonstrated existence of both PM and EM phenotypes in the Indian population. Based on the overall data (n=144 subjects) there appeared to be 10.4% of PM phenotypes for fluoxetine and/or possibly for other polymorphic CYP2D6 substrates commonly used in this region.