This dissertation describes the development of a new sustained release formulation of nifedipine. The new formulation was developed by coating commercially available immediate release soft elastic gelatin capsules using a spray coating technique with two different polymeric combinations. Dissolution studies were conducted and showed that controlled release of nifedipine was obtained by increasing the ratio of the water insoluble polymer in the coat and increasing the percent weight gain of the coating. Simulated plasma concentration versus time profiles after administration of 30 mg dose of selected formulations showed a prolonged nifedipine release with concentrations above the minimum effective concentration for up to 12 hours. Bioavailability and bioequivalence of tableted test formulation of verapamil HCL was determined in 8 volunteers and compared to Covera HS® under fed and fasting conditions. The 90% confidence intervals for individual percent ratios of the Cmax, AUC₀₋₅₈ and AUC₀ were not within the range of 80 - 125% in both fed fasted states, suggesting that these formulations are not bioequivalent. the bioavailability of verapamil from the new formulation was higher state but this effect was not statistically significant. Pharmacokinetics of terbinafine administered orally at single doses of 15, 30, 60 and 120 mg were determined in raptors to recommend an appropriate dosing scheduled for terbinafine in the treatment of Aspergillosis. Calculation of steady state trough terbinafine plasma concentration after administration of daily doses of 15 or 30 mg/day showed that 30 mg daily dose of terbinafine administered orally in raptors produces a steady state trough terbinafine plasma concentration above the minimum inhibitory concentration (MIC) of(0.8 1.6) µg/ml against aspregillus fumigatus. From the data, 30 mg per day oral dose of terbinafine should be the recommended dose for treatment of aspergillosis in raptors. Approximate pharmacokinetic linearity of terbinafine was demonstrated for AUC[subscript 0-t] in the dose range of 15 120 mg while non-linearity for Cmax in the same dose range was demonstrated using the power model. / Graduation date: 2005

This thesis examines the transport of exogenous molecules across the blood-brain barrier (BBB), focusing on active efflux, using positron emission tomography (PET), computer simulation and modelling. P-glycoprotein (P-gp) inhibition was studied using [11C]verapamil and [11C]hydroxyurea was investigated as a new marker for active efflux transport. Simulations were carried out to explore the importance of the efflux transporter location in the BBB. Brain concentrations of [11C]verapamil, [11C]GR205171 and [18F]altanserin were compared in various laboratory animal species and in humans. A central aspect of the studies has been the novel combination of dynamic PET imaging of the brain pharmacokinetics of a labelled drug, administered through an exponential infusion scheme allowing time-resolved consequence analysis of P-gp inhibition, and mathematical modelling of the obtained data. The methods are applicable to drugs under development and can be used not only in rodents but also in higher species, potentially even in humans, to investigate the effects of P-gp or other transporters on drug uptake in the brain. The inhibition of P-gp by cyclosporin A (CsA) and the subsequent change in brain concentrations of [11C]verapamil occurred rapidly in the sense that [11C]verapamil uptake increased rapidly after CsA administration but also in the sense that the increased uptake was rapidly reversible. The P-gp inhibition was best described by an inhibitory indirect effect model in which CsA decreased the transport of [11C]verapamil out of the brain. The model indicated that approximately 90% of the transport of [11C]verapamil was P-gp-mediated. The low brain concentrations of [11C]hydroxyurea appeared to be a result of slow transport across the BBB rather than active efflux. This exemplifies why the extent and the rate of brain uptake should be approached as two separate phenomena. The brain-to-plasma concentration ratios for the three studied radiotracers differed about 10-fold be-tween species, with lower concentrations in rodents than in humans, monkeys and pigs. The increase in brain concentrations after P-gp inhibition was somewhat greater in rats than in the other species. The findings demonstrate a need to include the dynamics of efflux inhibition in the experimental design and stress the importance of the choice of species in preclinical studies of new drug candidates.

The main objective of this thesis was to investigate the in vivo relevance of membrane transporters and cytochrome P450 (CYP) 3A4-mediated metabolism in the intestine and liver for the bioavailability of drugs in humans after oral administration. In the first part of the thesis, the main transport mechanisms involved in the intestinal absorption and bioavailability were investigated for fexofenadine, a minimally metabolized drug, which is a substrate for P-glycoprotein (P-gp) and members of organic anion transporting polypeptide (OATP) family. Jejunal perfusion studies revealed that co-perfusion with verapamil increased the bioavailability of fexofenadine by decreasing the first-pass liver extraction as the low intestinal permeability was unchanged by the transport inhibitors studied. The mechanism behind the interaction probably involves inhibition of OATP-mediated sinusoidal uptake and/or P-gp-mediated canalicular secretion of fexofenadine. Results from the Caco-2 model supported that the intestinal absorption of fexofenadine is mainly determined by the low passive permeability of the drug, even though fexofenadine clearly is a P-gp substrate. In the second part of the thesis, the effect of repeated oral administration of the P-gp and CYP3A4 inducer St. John’s wort on the in vivo intestinal permeability and presystemic metabolism of the dual P-gp and CYP3A4 substrate verapamil was investigated in a jejunal perfusion study. St. John’s wort decreased the bioavailability of the enantiomers of verapamil by inducing the CYP3A4-mediated presystemic metabolism, probably mainly in the gut. It was also concluded that induction of efflux transporters, such as P-gp, does not affect the intestinal transport or the gut wall extraction of high permeability substrates like verapamil. Data from Caco-2 cells with induced CYP3A4-activity supported these findings. The plasma levels of the enantiomers of norverapamil also decreased despite an increased formation, which was attributed to induction of CYP3A4 and/or other metabolic routes.

Submitted by VINÍCIUS DANILO NONATO BEZZON null (vinicius.bezzon@gmail.com) on 2017-05-17T22:08:46Z No. of bitstreams: 1 Tese_doutorado_completo_final_V2.pdf: 4483860 bytes, checksum: 671f1404e48641f67de0908f91f8dd62 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-05-19T12:35:15Z (GMT) No. of bitstreams: 1 bezzon_vdn_dr_bauru.pdf: 4483860 bytes, checksum: 671f1404e48641f67de0908f91f8dd62 (MD5) / Made available in DSpace on 2017-05-19T12:35:15Z (GMT). No. of bitstreams: 1 bezzon_vdn_dr_bauru.pdf: 4483860 bytes, checksum: 671f1404e48641f67de0908f91f8dd62 (MD5) Previous issue date: 2017-03-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Medicamentos de liberação controlada (MLC) vêm ganhando destaque no mercado farmacêutico nacional e internacional pelos seus mais diversos benefícios, principalmente por manter a atividade do princípio ativo (PA) no organismo em uma faixa constante de eficiência. Dentre os sistemas MLC estão as dispersões sólidas amorfas (DSA), que possuem como componentes o fármaco e a matriz polimérica. Devido à complexidade da estrutura de liberação destas dispersões, são necessárias técnicas e metodologias analíticas mais sofisticadas para o controle e qualidade da formulação final. A técnica de espalhamento total de raios X (ETRX) e o método Pair Distribution Function (PDF) vêm sendo utilizados no estudo de materiais com estrutura com ordem de curto e intermediário alcance, incluindo fármacos amorfos e nanocristalinos, além de dispersões sólidas fármaco/polímero, sendo possível fazer a distinção entre as fases a nível intra e intermoleculares, o que representa as potencialidades do ETRX e o PDF para a caracterização estrutural de materiais. Nesse contexto, desenvolveu-se a análise estrutural das DSA's do cloridrato de Verapamil e resina poliuretânica derivada do óleo de mamona por meio das técnicas RMN, FTIR e difração de raios X convencional. Por meio dessas análises criou-se o embasamento necessário para aplicar o ETRX e método PDF e avaliar as potencialidades no estudo de sistemas complexos, como os que foram objetos de análise neste trabalho. Os resultados mostraram que fármaco e resina são miscíveis, e assim, formam sistemas de dispersão molecular, nos quais as moléculas do fármaco estão dispersas homogeneamente nas cadeias poliméricas da poliuretana. Devido às fortes interações entre os componentes por meio de ligações de hidrogênio, o PA é mantido amorfo na matriz. No entanto, o acréscimo da quantidade de fármaco resulta no aumento das distâncias entre os átomos nas ligações de hidrogênio, o que facilita sua difusão através da resina, promovendo assim o aumento da liberação do fármaco no processo de liberação controlada. / Controlled-Release Drugs (CRD) have increasingly been chased by the national and international pharmaceutical market because their different benefits, mostly by it can keep the activity of the Active Pharmaceutical Ingredient (API) in the body in a continuous range of efficiency. Among others, CRD systems are the amorphous solid state dispersions, which have API and polymer matrix as components of the systems. Due to complexity of the release structure of these dispersions, sophisticated analytical techniques and methodologies are required for the control and quality of the final formulation. The X-ray total scattering technique (XRTS) and the Pair Distribution Function (PDF) method have been used to study materials with short- and intermediaterange order structure, including amorphous and nanocrystalline drugs, as well as drug/polymer solid dispersions, making it possible to discriminate between phases at intra and intermolecular levels, which represents the potentialities of the XRTS and the PDF for the structural characterization of materials. In this context, the present work has developed the structural analysis of the amorphous solid dispersions of Verapamil Hydrochloride and polyurethane resin derived from castor oil using NMR, infrared spectroscopy and conventional X-ray diffraction techniques. Through this initial analysis, it was possible to create the necessary basis for the application of XRTS and PDF method and evaluate its potential to study complex systems, such as those objects of analysis. Overall, the results showed that drug and resin are miscible, and thus the systems represent molecular dispersions in which the API molecules are homogeneously dispersed in the polyurethane polymer chains. Due to the strong interactions between the components through hydrogen bonds, the API is kept amorphous in the matrix. However, to increase the proportion of the API increases the distances between the atomic species in the hydrogen bonds, which facilitates their diffusion through the resin, hence promoting the growth of the API release in the controlled release process.

Aim: The general aim of this research is development and evaluation of novel methods for predicting active transport over the human blood-brain-barrier (BBB), while this project specifically aims to i) review the literature and select suitable methods and substrates, ii) develop models for determining in vitro kinetic properties of selected compounds, analyze the in vitro data using the developed models and to use Maximum Transport Activity (MTA) approach (Karlgren et al., 2012), iii) perform Physiology Based Pharmacokinetic (PBPK) modelling and compare to in vivo literature data. Background: Drug permeation to the brain through blood circulation is primarily limited by blood-brain barrier (BBB), due to existence of tight junctions in endothelial cells of blood vessels as well as active efflux and influx transporters in the barrier. Toxicity and CNS related side effects can be caused by peripheral targeted drugs crossing BBB. Hence, prediction of BBB permeability and estimation of drug concentration in the brain tissue are challenging in drug discovery. To resolve this, estimating the human BBB permeability using improved in vitro and in silico predictive models can be a facilitator. Methods: In vitro data provided by the Drug Delivery research group was used to develop in vitro predictive models for BBB penetration of Verapamil, Risperidone, and Prazosin using R-studio 1.2.5. The MTA approach was adjusted for extrapolation of BBB in vitro transporter activity to in vivo condition. For PBPK modelling, we took advantage of PK-Sim® to simulate drug disposition and time profile of Risperidone in human and animal species. Results: It was shown that MDR1 is the major transporter for efflux transport of Prazosin and Risperidone in brain while both BCRP and MDR1 have similar impact on transport of Verapamil. Furthermore, it was presented in PBPK models that the predicted brain concentration of Risperidone increases in rat and nonhuman primate (NHP) when MDR1 And BCRP are knocked out while the brain concentration of Risperidone in dog is not affected by expression level of the efflux transporters. Conclusion: Both MDR1 and BCRP are contributing in efflux transport of Verapamil, Risperidone, and Prazosin across the BBB. Additionally, expression of the efflux transporters shown to have an impact on brain exposure of Risperidone in animal PBPK models.

Thesis (PhD)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: The reperfusion injury after myocardial ischemia is relevant in the clinical setting, after cardiopulmonary bypass for cardiac surgery, after PTCA and stenting and after cardiopulmonary resuscitation. The components of the reperfusion injury considered in this study were myocardial stunning and reperfusion arrhythmias. Calcium antagonists have been shown to be beneficial in attenuating the myocardial reperfusion injury in the in vitro and in vivo laboratory setting (Lamping, Gross 1985, Przyklenk and Kloner 1988, Taylor 1990, Ehring 1992, Gross and Piper 1992). However systemic administration of a dose of calcium antagonist, large enough to attenuate the myocardial reperfusion injury in the clinical setting, would inevitably lead to unwanted systemic side effects of the drug. The aim of this study was to investigate the hypothesis that an adequate dose of verapamil administered timeously, directly into the ischemic myocardium, would attenuate the reperfusion injury, either when administered from the onset of ischemia, or from 3 minutes before reperfusion. The anesthetized open chest porcine model of myocardial ischemia (15 min total LAD occlusion) and reperfusion was employed in this study. A low dose of verapamil (0.5 mg/8mt or 0.0625mg/mt), a high dose of verapamil (2mg/8m or O.25mg/ml), or vehicle (saline) (8ml) was infused over 8 minutes, directly into the LAD coronary artery supplying the ischemic segment. The infusion was started either at the onset of ischemia, or from 3 minutes before reperfusion. The time taken for the various parameters to return to pre ischemic values was compared between the different groups. The results showed that the high dose of verapamil (2mg) attenuated the reperfusion injury both when administered from the onset of ischemia, and when administered from 3 minutes before reperfusion, compared to either the low dose of verapamil, or the saline infusions. The high dose of verapamil groups had a faster recovery of both systolic contractile function and diastolic function and a lower incidence of ventricular fibrillation on reperfusion. There were no systemic effects of verapamil infusion in any of the groups. The clinical setting of cardiac surgery expressly lends itself to the clinical application of this finding. There is direct access to the coronary arteries both before ischemia and before reperfusion. A small dose of calcium channel blocking drug, with no systemic effect can be administered into the aortic root at the onset of ischemia, just prior to cardioplegia (when the heart is still warm), and after rewarming a few minutes prior to removal of the aortic cross clamp. / AFRIKAANSE OPSOMMING: Die reperfusie besering na miokardiale isgemie is klinies relevant na kardiopulmonêre omleiding vir hart chirurgie, na kardiologiese PTKA en stut prosedures en na kardiopulmonale ressussitasie. Die komponente van die reperfusie besering wat in hierdie studie oorweeg is, is miokardiale tydelike omkeerbare onderdrukking (stunning) en reperfusie arritmieë. Kalsium antagoniste is gewys om effektief te wees in beperking van die reperfusie besering in beide in vitro en in vivo laboratorium eksperimente (Lamping, Gross 1985, Przyklenk en Kloner 1988, Taylor 1990, Ehring 1992, Gross en Piper 1992). Sistemiese toediening van 'n dosis kalsium kanaal blokker, voldoende om die miokardiale reperfusie besering in die pasiënt te beperk, lei egter tot ongewenste sistemiese newe effekte van die middel. Die doel van die studie was om die hipotese te ondersoek dat 'n voldoende dosis verapamil, wat betyds direk toegedien is aan die isgemiese miokardium, die reperfusie besering sal beperk, ongeag of dit toegedien is vanaf die begin van isgemie, of van 3 minute voor reperfusie. Die vark model van miokardiale isgemie en reperfusie is aangewend in die studie. Die varke was tydens die eksperiment onder narkose, met die borskas oop, en 15 minute totale LAD okklusie is toegepas. 'n Lae dosis verapamil (0.5mg/8ml of 0.0625 mg/mt), of hoë dosis veraparnil (2mg/8mt of 0.25mg/mt), of saline (8mt) is oor 8 minute toegedien direk in die LAD arterie wat die isgemiese segment voorsien. Die infuus is begin direk na die aanvang van isgemie, of 3 minute voor die aanvang van reperfusie. Die tyd geneem vir terugvoer van parameters na pre isgemiese waardes is tussen die groepe vergelyk. Die resultate toon dat die hoë dosis veraparnil die reperfusie besering beperk in vergelyking met die lae dosis veraparnil of saline infusies, ongeag of dit van die begin van isgemie, of van 3 minute voor reperfusie toegedien word. Die groepe wat die hoë dosis veraparnil ontvang het, het vinniger herstel van sistoliese en diastoliese funksie getoon en het'n laer insidensie van reperfusie disritmieë, gewys. Geen sistemiese effekte van veraparnail infuus is waargeneem nie. Die kliniese toepassing van hierdie bevinding is by uitstek geskik vir toepassing tydens kardiopulmonale omleiding by kardiale chirurgie. Daar is direkte toegang tot koronêre arteries voor isgemie en voor reperfusie. 'n Klein dosis kalsium antagonis, met weglaatbare sistemiese effekte, kan toegedien word in die aorta wortel met die aanvang van isgemie, net voor kardioplegie toediening (hart steeds warm), en na verwarming, 'n paar minute voor verwydering van die aorta kruis klem.

In this thesis, we included results from two studies. The first one considered the effects of the blood volume changes, during blood donation, on the heart rate variability (HRV) measured, non-invasively, form electrocardiographic (ECG) and photoplethysmographic (PPG) signals. Our results showed that, during blood donation, there were no significant changes in the pulsatile area of PPG signal, while heart rate increased. No significant changes were noticed in HRV extracted from both signals. Error analysis between the HRV extracted from ECG and peak interval variability (PIV) suggested that the error during blood donation was increased which means that the use of PIV extracted from PPG signal, used as a replacement diagnostic tool in clinical applications, needs further investigations and should be carefully studied in non-stationary cardiovascular situations such as blood donation. The imbalance between the two branches of the autonomic nervous system, sympathetic and parasympathetic, vagal, may result in a harmful activation of myocardial tissues which cause arrhythmias and sudden cardiac death. Although the study of the sympathovagal balance have been attracting many researchers, further studies are needed to elucidate the effects of many kinds of drugs on the autonomic modulation of the cardiac muscle, specifically, the cells of sinoatrial (SA) node. The aim of the second part of this thesis was to assess the effects of calcium channel blocker (Verapamil), calcium channel sensitizer (Levosimendan), calcium chloride (CaCl2), the combinations of verapamil/ CaCl2, levosimendan/ CaCl2, and noradrenaline infusion on beat-to-beat cardiovascular variability represented, in this research, by systolic blood pressure variability (SBPV), and stroke volume variability (SVV) signals. We used Fat Fourier Transform (FFT) to evaluate the power spectral density of the fluctuations in both signals to evaluate the effects of short-term treatments with those drugs on the sympathovagal balance in normal rats. Then, we compared the spectra obtained from SBPV and SVV to decide which of these fluctuations along with corresponding spectrum was more able to provide a clear feedback about the autonomic nervous system. Our data suggests that there were a significant correlations between low- (LF), mid- (MF), and high-frequency (HF) spectra obtained from SBPV and SVV except between the HF spectra estimated from after the infusion of levosimendan where a poor correlation (r = 0.530, p = 0.281) was noticed. This that both HF components obtained provide different information regarding the autonomic nervous system modulation of the SA node cells, while the results obtained from the rest of experiments showed that both signals provide same information about the modulation of sympathetic and parasympathetic tone due to all stages of different drugs infusion studied in this thesis. Besides that, we found that both spectra may be used to track the fluctuations in the cardiac output as a result of the drugs infusion.

Les transporteurs ABC forment une vaste famille de protéines présentes dans tous les organismes vivants. Ces protéines utilisent l'énergie fournie par l'hydrolyse de l'ATP pour transporter à travers les membranes biologiques des substances très variées. Plusieurs protéines ABC sont importantes pour la santé humaine. Par exemple, le défaut fonctionnel de la protéine CFTR cause la mucoviscidose et la surproduction de protéine MRP1 est associée aux phénomènes de résistance aux traitements anti-tumoraux. La levure Saccharomyces cerevisiae possède une famille de protéines (Yor1p, Ycf1p, Bpt1p, Ybt1p, Vmr1p, Nft1p) apparentées à CFTR et MRP1. Cette famille peut servir de modèle à l'étude des protéines humaines. La première partie de ce travail de thèse a été consacrée à l'étude biochimique de la protéine de levure Yor1p. Nous avons fusionné YOR1 avec un fragment d'ADN codant un peptide de poly-histidine et avons placé cette construction sous contrôle d'un promoteur permettant une surproduction dans la levure. Nous avons alors montré que la protéine Yor1p poly-histidylée était produite sous forme fonctionnelle dans la levure, puis avons mis au point une méthode permettant de solubiliser puis de purifier cette protéine en une seule étape par chromatographie d'affinité sur une colonne greffée avec des ions métalliques. La deuxième partie de ce travail a consisté à produire sous forme isolée chez la bactérie Escherichia coli et à purifier à homogénéité les deux domaines de Yor1p impliqués dans la liaison et l'hydrolyse de l'ATP. Nous avons étudié la fixation de l'ATP sur ces deux domaines, ce qui nous a permis de conclure que ces domaines étaient bien structurés. Ils peuvent maintenant être utilisés pour des études structurales. Enfin, nous nous sommes intéressés au rôle la protéine Ycf1p dans la détoxication du sélénite. Nous avons observé que la toxicité du sélénite pour la levure était considérablement accrue par la présence de composés thiolés dans le milieu de culture. La formation de dérivés réactifs de l'oxygène est vraisemblablement à l'origine de cette hypertoxicité.

In this thesis, we included results from two studies. The first one considered the effects of the blood volume changes, during blood donation, on the heart rate variability (HRV) measured, non-invasively, form electrocardiographic (ECG) and photoplethysmographic (PPG) signals. Our results showed that, during blood donation, there were no significant changes in the pulsatile area of PPG signal, while heart rate increased. No significant changes were noticed in HRV extracted from both signals. Error analysis between the HRV extracted from ECG and peak interval variability (PIV) suggested that the error during blood donation was increased which means that the use of PIV extracted from PPG signal, used as a replacement diagnostic tool in clinical applications, needs further investigations and should be carefully studied in non-stationary cardiovascular situations such as blood donation. The imbalance between the two branches of the autonomic nervous system, sympathetic and parasympathetic, vagal, may result in a harmful activation of myocardial tissues which cause arrhythmias and sudden cardiac death. Although the study of the sympathovagal balance have been attracting many researchers, further studies are needed to elucidate the effects of many kinds of drugs on the autonomic modulation of the cardiac muscle, specifically, the cells of sinoatrial (SA) node. The aim of the second part of this thesis was to assess the effects of calcium channel blocker (Verapamil), calcium channel sensitizer (Levosimendan), calcium chloride (CaCl2), the combinations of verapamil/ CaCl2, levosimendan/ CaCl2, and noradrenaline infusion on beat-to-beat cardiovascular variability represented, in this research, by systolic blood pressure variability (SBPV), and stroke volume variability (SVV) signals. We used Fat Fourier Transform (FFT) to evaluate the power spectral density of the fluctuations in both signals to evaluate the effects of short-term treatments with those drugs on the sympathovagal balance in normal rats. Then, we compared the spectra obtained from SBPV and SVV to decide which of these fluctuations along with corresponding spectrum was more able to provide a clear feedback about the autonomic nervous system. Our data suggests that there were a significant correlations between low- (LF), mid- (MF), and high-frequency (HF) spectra obtained from SBPV and SVV except between the HF spectra estimated from after the infusion of levosimendan where a poor correlation (r = 0.530, p = 0.281) was noticed. This that both HF components obtained provide different information regarding the autonomic nervous system modulation of the SA node cells, while the results obtained from the rest of experiments showed that both signals provide same information about the modulation of sympathetic and parasympathetic tone due to all stages of different drugs infusion studied in this thesis. Besides that, we found that both spectra may be used to track the fluctuations in the cardiac output as a result of the drugs infusion.

Data de aprova??o ausente. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-03-24T17:42:56Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) amanda_barbosa_lima.pdf: 1709527 bytes, checksum: 4fddb4fdbd889c4c7f3a82be7a0edabe (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-04-20T19:16:33Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) amanda_barbosa_lima.pdf: 1709527 bytes, checksum: 4fddb4fdbd889c4c7f3a82be7a0edabe (MD5) / Made available in DSpace on 2017-04-20T19:16:33Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) amanda_barbosa_lima.pdf: 1709527 bytes, checksum: 4fddb4fdbd889c4c7f3a82be7a0edabe (MD5) Previous issue date: 2016 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Verapamil (VP) e Oxcarbazepina (OX) s?o f?rmacos de baixo ?ndice terap?utico que necessitam de rigoroso controle de qualidade em formula??es farmac?uticas, bem como de an?lises em fluidos biol?gicos para estudos farmacol?gicos de elimina??o dessas drogas. Neste sentido, o desenvolvimento de m?todos simples, r?pidos e de baixo custo ? de extrema import?ncia para quantifica??o desses f?rmacos nessas amostras. Deste modo, o presente trabalho apresenta um m?todo eletroanal?tico em fluxo para determinar VP e OX tanto em formula??es farmac?uticas, quanto em amostras de urina. A t?cnica eletroqu?mica utilizada para quantifica??o foi a Amperometria de M?ltiplos Pulsos (MPA) acoplada a um sistema de an?lise por inje??o em fluxo (FIA), utilizando o diamante dopado com boro (BDD). Foram aplicados tr?s pulsos de potencial pela MPA para determina??o do VP em meio de ?cido sulf?rico 0,1 mol L-1, sendo +1,6 V para a oxida??o e, posteriormente, +0,2 V para redu??o do produto gerado do VP e +0,1 V para a limpeza do eletrodo de BDD. Para a determina??o de OX, tamb?m foram otimizados tr?s pulsos de potencial em meio de tamp?o acetato 0,1 mol L-1 (pH 4,0), sendo + 1,7 V para a oxida??o da OX e gera??o do produto que foi reduzido em -1,1 V e -1,3 V para a limpeza do eletrodo de BDD. Em ambos os casos, apenas o sinal obtido nos pulsos de potencial de redu??o foram utilizados para quantifica??o dos f?rmacos. As faixas lineares de trabalho obtidas para quantifica??o do VP e da OX foram de 0,8 a 40,0 ?mol L-1 (R= 0,9976) e 2,0 a 80,0 ?mol L-1 (R= 0,9989), respectivamente. Os limites de detec??o foram calculados em 0,16 ?mol L-1 para VP e 0,42 ?mol L-1 para OX. Uma boa repetibilidade foi obtida para 10 an?lises consecutivas desses f?rmacos, com desvio padr?o relativo de 2,2% para VP e 0,94 % para OX. Os estudos de adi??o e recupera??o do VP e OX em amostras farmac?uticas e urina apresentaram resultados pr?ximos a 100% e o doseamento do VP foi validado pela metodologia oficial. Altas frequ?ncias anal?ticas foram alcan?adas pelo sistema FIA com 45 e 65 determina??es por hora de VP e OX, respectivamente, usando al?as de amostragem inferiores a 200 ?L e vaz?es de 3,5 mLmin-1. An?lises desses f?rmacos em amostras de urina mostraram que ? poss?vel determin?-los mesmo na presen?a de altas concentra??es de ?cido asc?rbico e ?cido ?rico. Portanto, o m?todo proposto mostrou-se como alternativa simples e r?pida para quantifica??o desses f?rmacos em formula??es farmac?uticas e urina. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, [2016]. / Verapamil (VP) and Oxcarbazepine (OX) are drugs of narrow therapeutic index that require strict quality control in pharmaceutical formulations and analysis in biological fluids for pharmacological studies of elimination of these drugs. In this sense, the development of simple, fast and low-cost methods is very important to quantify these drugs in pharmaceutical samples. Therefore, this work presents a electroanalytical method in flow for determining VP and OX in pharmaceutical formulations and human urine samples. The electrochemical technique used for quantification was performed by multiple pulses amperometry (MPA) coupled to a flow injection analysis system (FIA), using boron-doped diamond (BDD) as working electrode. Were applied three potential pulses by MPA for the determination of VP in sulfuric acid 0.1 mol L-1: (1) +1.6 V for oxidation of VP, (2) +0.2 V for reduction of the generated product of VP in the fisrt potential pulse, (3) +0.1 V for cleaning of the BDD electrode surface. The determination of OX also was performed by MPA in three potential pulses in 0.1 mol L-1 acetate buffer (pH 4.0): (1) +1.7 V for oxidation of OX and generation of the product that it was reduced at (2) -1.1 V, and (3) -1.3 V for cleaning of the BDD electrode surface. In both cases, only the signal obtained in the reduction potential pulses were used for quantification of drugs. The linear ranges of work obtained for quantitation of VP and OX were 0.8 to 40.0 ?mol L-1 (R = 0.9976) and 2.0 to 80.0 ?mol L-1 (R = 0, 9989), respectively. The detection limits were calculated to be 0.16 ?mol L-1 for VP and 0.42 ?mol L-1 for OX. Good repeatabilities were obtained for 10 consecutives injections of these drugs, with relative standard deviation of 2.2% for VP and 0.94% for OX. The addition and recovery studies for VP and OX in pharmaceutical and urine samples were close to 100% and determination of VP was validated by the official methodology. High analytical frequencies were achieved by FIA system of 45 and 65 determinations per hour for VP and OX, respectively, using sampling handles less than 200 ?L and flow rate of 3.5 mLmin-1. The analysis of these drugs in urine showed that it is possible to determine this sample even in the presence of high concentrations of ascorbic acid and uric acid. Therefore, the present method by MPA-FIA proved to be a quick and easy alternative to quantify VP and OX in pharmaceutical formulations and urine.