Malgré l'existence d'un vaccin et de différentes molécules antituberculeuses, l'infection par Mycobacterium tuberculosis est toujours l'un des principaux problèmes de santé publique au niveau mondial. Le traitement standard, bien qu'efficace, est long et difficile à mettre en œuvre. Par ailleurs, l'un des principaux challenges actuels est la prise en charge des formes résistantes de tuberculose, dont la prévalence est en augmentation constante. Nous avons souhaité mettre à profit les techniques récentes de modélisation in silico pour mieux comprendre l'action d'un des antituberculeux majeurs, l'isoniazide. L'objectif de ce travail est de construire un modèle mathématique global du traitement de la tuberculose pulmonaire par l'isoniazide basé sur des éléments pharmacocinétiques, pharmacodynamiques et physiopathologiques.En utilisant une approche de population, un modèle pharmacocinétique de diffusion pulmonaire a permis de décrire les concentrations en isoniazide dans le plasma et le poumon de 89 sujets. Des simulations réalisées à partir de ce modèle ont permis de montrer, par combinaison avec un modèle pharmacodynamique, qu'une individualisation de la posologie avec augmentation de la dose chez les métaboliseurs rapides de l'isoniazide n'aurait d'intérêt qu'en cas d'infection par une souche de M. tuberculosis de sensibilité intermédiaire. Ce modèle pharmacocinétique a ensuite été couplé à un modèle pharmacodynamique et à un modèle de la physiopathologie de la tuberculose pour construire un modèle mathématique thérapeutique global. Ce dernier a permis de simuler la dynamique bactérienne à partir du premier jour de l'infection et pour les deux premières semaines de traitement par isoniazide, et de reproduire certaines caractéristiques qualitatives et quantitatives de l'effet antibactérien initial de l'isoniazide connues en clinique. Les analyses réalisées sur ce modèle ont permis de mieux comprendre les déterminants de la dynamique bactérienne et notamment le ralentissement de l'effet antibactérien après les premiers jours de traitement / Despite the availability of a vaccine and several antituberculosis drugs, tuberculosis, an infection caused by Mycobacterium tuberculosis still remains a major public health concern worldwide. The standard treatment of tuberculosis is efficient but is long and hard to conduct. We decided to use recent in silico modeling techniques to improve our understanding of the action of isoniazid, one of the major antituberculosis drugs. The aim of this work was to build a full mathematical model reproducing the treatment of pulmonary tuberculosis by isoniazid, based on pharmacokinetics, pharmacodynamics and physiopathological data. A pulmonary pharmacokinetic model was developed in order to describe plasma and pulmonary isoniazid concentrations from 89 subjects. This model was used to perform simulations and was coupled to a pharmacodynamic model. The simulations showed that individualizing the dose according to the isoniazid metabolizer status would only be beneficial in fast metabolizers infected with a strain of intermediate sensitivity. This pharmacokinetic model was then integrated to a full mathematical model including a pharmacodynamic and an immune response model. This model adequately reproduced the bacterial dynamics over the development of the infection and its early treatment with isoniazid. It reproduced qualitative and quantitative features of the antimicrobial effect of isoniazid in agreement with clinical data. The simulations and analysis performed enabled us to better characterize the parameters influencing the bacterial dynamics and especially why the antibacterial effect tends to diminish after the first days of treatment

[pt] O presente trabalho trata da síntese, caracterização e estudo espectroscópico de novo ligante derivado da reação do ácido barbitúrico e isoniazida e seus respectivos complexos de zinco e cobre que foram todos igualmente estudados. Foi proposto um roteiro de síntese em meio aquoso utilizando metodologia gráfica para delinear as melhores condições de obtenção dos produtos. Um estudo espectroscópico completo dos reagentes foi realizado para ajudar na caracterização do ligante e dos complexos. A interpretação dos espectros de infravermelho e Raman foi acompanhada com os cálculos mecânico-quânticos utilizando o método DFT/B3LYP e o conjunto de base 3-21G acompanhado com os dados experimentais obtidos pela análise da segunda derivada do espectro. Os espectros de infravermelho com transformada de Fourier, e Raman tendo como base a estrutura proposta de acordo com os dados de CHN, RMN e absorção atômica, apresentaram uma excelente concordância com os espetros experimentais. A baixa solubilidade do ácido barbitúrico e seus derivados em regiões de pH acima de 5 produz uma mistura de hidroxo-complexos que dificulta o estudo das regiões de baixa energia, onde os modos vibracionais metal-ligante ocorrem. A metodologia gráfica empregada permitiu a obtenção de produtos mais puros e cristalizados possibilitando a correta caracterização espectroscópica de todos os modos vibracionais. / [en] The present study examined the synthesis, characterization, and spectroscopic study of new ligand derived from the reaction of barbituric acid and isoniazid. The ligand was used to synthetize complexes of zinc and copper and these complexes were analyzed. A synthesis plan was proposed in an aqueous medium using a graphical methodology, ensuring the best conditions to obtain the products. A complete spectroscopic study of reagents was implemented to aid in the characterization of both the ligand and the complexes. The interpretation of infrared spectra and Raman was complemented with a quantum-mechanical calculation method using DFT / B3LYP and a 3-21G basis. These calculations were compared with experimental data obtained by analyzing the second derivative of the spectrum. Based on the structure proposed according to the data of CHN, NMR, and the atomic absorption; the infrared spectra with a transformed Fourier and Raman were in line with the experimental spectra. Lastly, these conclusions lead us to better understand the complexities in spectroscopic characterization of compounds derived from barbituric acid and its coordination compounds. The low solubility of barbituric acid and its derivatives in pH regions above 5 creates a mixture of hydroxide complexes which complicate the study of low energy regions, where the metal-ligand vibrational modes occur. The graphical methodology used allowed us to obtain purer crystallized products, enabling the correct spectroscopic characterization of all vibrational modes.

Thesis (MScMedSc)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Isoniazid forms part of the first line anti-tuberculosis therapy and it is generally used to treat latent Mycobacterium tuberculosis infection. Isoniazid inhibits synthesis of long chain mycolic acids found in cell wall of Mycobacterium tuberculosis, which have proven vital for the survival of the bacterium. Mycolic acids are primarily synthesized by the fatty acid synthase enzyme (FAS) system found in mycobacteria as the FAS-I and FAS-II complex. Isoniazid kills the bacteria by blocking the FAS-II complex, required for extension of mycolates. It does this by entering the tubercle bacilli as a prodrug where isoniazid becomes activated by catalase peroxidase encoded by katG gene. The activated isoniazid then forms a complex with NAD+ which targets InhA (NADH-dependent enoyl-acyl carrier protein reductase) located in the FAS-II complex. Loss of catalase peroxidase, due to gene mutations or a complete katG gene deletion is one of the primary mechanisms conferring resistance to INH in Mycobacterium tuberculosis. In addition, four other genes (inhA, KasA, ndh and ahpC) are also associated with INH resistance. Nonetheless, mutations in these five genes are present in only 70-80% of INH resistant clinical isolates, implying that other mechanisms are involved in resistance of Mycobacterium tuberculosis to isoniazid. This study aims to quantify the expression level of genes induced by isoniazid in the mycolic acid pathway and drug transport in two closely related Mycobacterium tuberculosis Beijing cluster 208 isolates. These are the fully susceptible (K636) and isoniazid mono-resistance strains (R55), with minimum inhibitory concentrations of 0.1 and 4 µg/ml, respectively. Both these isolate had no isoniazid gene associated mutations. The isolates were cultured in the presence and absence of 0.1µg/ml isoniazid for 24 hours after which RNA was extracted followed by QRT-PCR analysis to identify differentially expressed genes. This result has shown that various genes were differentially expressed in response to low level INH exposure. The most significant up-regulation was observed in genes (acpM, fabD, Accd6 and fbpC) encoding the FAS-II complex and genes (efpA, iniA, iniB, and mmpl7) involved in drug transport. In addition, two genes (ndh and fbpC) were significantly down-regulated in the isoniazid mono-resistant isolate. Based on these findings, we propose a model whereby isoniazid exposure in the susceptible isolate inhibits FAS-II complex and with its associated accumulation in mycolates kills the bacterium. In contrast, we propose that in the resistance isolate the bacterium acquires additional resistance by the activation of efflux pumps in combination with disruption in INH-NAD+ complex formation that protect inhibition of InhA located in FAS-II complex. / AFRIKAANSE OPSOMMING: Isoniasied vorm deel van die eerste linie van behandeling teen tuberkulose en word algemeen gebruik om latente Mycobacterium tuberculosis infeksie te behandel. Isoniasied inhibeer die sintese van langketting mikolitiese sure wat in die selwand van Mycobacterium tuberculosis voorkom. Dit is bewys dat hierdie sure essensieel is vir die oorlewing van die bakterie. Mikolitiese sure word hoofsaaklik gesintetiseer deur die vetsuur sintase ensiem (FAS) sisteem wat in mikobakteriee voorkom as die FAS-I en FAS-II komplekse. Isoniasied dood die bakteriee deur die FAS-II kompleks, wat nodig is om die verlenging van mikoliete, te blokkeer. Dit word bewerkstellig deurdat 'n pro-vorm van die middel die tuberkulose bacilli binnedring, waarna isoniasied geaktiveer word deur katalase peroksidase, wat deur die katG geen geenkodeer word. Die geaktiveerde isoniasied vorm 'n kompleks met NAD+, wat InhA (NADH-afhanklike eno.asiel draer prote.enreduktase), gelee in die FAS-II kompleks teiken. Een van die primere meganismes wat weerstandigheid teen isoniasied bewerkstellig, is die verlies van katalase peroksidase weens geenmutasies of algehele delesie van die katG geen. 'n verdere vier gene (inhA, kasA, ndh en ahpC) word ook verbind met isoniasied weerstandigheid. Nietemin is mutasies in hierdie vyf gene teenwoordig in slegs 70-80% van isoniasied weerstandige kliniese isolate, wat impliseer dat ander meganismes ook betrokke is in die weerstandigheid van Mycobacterium tuberculosis teen isoniasied. Die doel van hierdie studie is om die vlak van uitdrukking van gene wat deur isoniasied in die mikolitiese suur biochemiese pad geïnduseer word, asook middel transport te kwantifiseer in twee naby verwante Mycobacterium tuberculosis isolate van Beijing groep 208. Die twee isolate is die volledig sensitiewe (K636) en isoniasied monoweerstandige (R55), met minimum inhiberende konsentrasies van onderskeidelik 0.1 en 4µg/ml. Mutasies wat geassosieer word met isoniasied weerstandigheid was afwesig in beide die isolate. Kulture is van die isolate gemaak met en sonder 0.1µg/ml isoniasied vir 24 uur, waarna RNA geekstraeer is deur middel van QRT-PCR analise om gene te identifiseer wat verskillend uitgedruk word. Die resultate toon dat verskeie gene verskillend uitgedruk is in reaksie op laevlak isoniasied blootstelling. Die mees prominente opregulering is waargeneem in die gene (acpM, fabD, accd6 en fbpC) wat die FAS-II kompleks enkodeer, asook die gene (efpA, iniA, iniB en mmpl7) wat betrokke is in middel transport. Beduidende afregulering van 'n verdere twee gene in die isoniasied monoweerstandige isolate, naamlik ndh en fbpC is waargeneem. Op grond van hierdie waarnemings, stel ons 'n model voor waarvolgens isoniasied blootstelling in die sensitiewe isolaat die FAS-II kompleks inhibeer, en met die gevolglike akkumulasie van mikoliete, dood dit die bakterium. In teenstelling stel ons voor dat addisionele weerstandigheid bekom word in die weerstandige isolaat deur die aktivering van uitvloeipompe, in kombinasie met die ontwrigting van die INH-NAD+ kompleksvorming wat die inhibisie van InhA binne die FAS-II kompleks beskerm.

Thesis (MBA)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Childhood tuberculosis is an infectious disease that can cause serious illness and mortality in especially young children. Following contact with an infectious adult tuberculosis case, the disease is easily preventable through preventive isoniazid treatment, yet very few exposed and at-risk children currently access this healthcare service in most high-burden settings. Previous research pointed out the multifactorial and complex nature of the barriers to accessing preventive care. Specifically, the lack of a formalised recording and reporting tool, such as the universally used tuberculosis treatment registers, possibly contribute to the operational barriers of preventive care delivery to these children. The purpose of this research was to evaluate the cost-effectiveness of an isoniazid preventive treatment register tool used at community level. The study utilised previously reported data from the study population and other high-burden settings to construct a decision analysis model that included varying probabilities of isoniazid preventive treatment across three high risk age groups (<1 year of age, 1 – 2 years of age, 3 – 5 years of age), coupled with disease probabilities and associated treatment costs. The scenarios simulated included 1) the routine isoniazid preventive treatment service (3% started on treatment, 17% identified as eligible); and 2) an isoniazid preventive treatment service supported by a recording register (15% (adherent to six months of treatment) and 38% (started on IPT treatment)). In addition, two hypothetical simulations were included for 76% and 100% isoniazid preventive treatment uptake; these hypothetical simulations required additional community based healthcare worker resources in addition to the register tool. The observations from the literature indicated that more children were identified (24(17%) vs. 54(38%)) and started (4(3%, base case) vs. 54) on isoniazid preventive treatment following the implementation of the register. As expected, the mean number of tuberculosis cases prevented, increased as the proportion of eligible children that received isoniazid preventive treatment, improved; the change in the number of cases prevented per simulation showed incremental improvements which were all significantly better (p<0.01) than the base case.. The incremental cost-effectiveness ratios incurred savings for each of the scenarios simulated since the mean costs for each of the simulations were significantly less (p<0.01) than the costs associated with the base case. The current evidence suggests that the proposed isoniazid preventive treatment register tool is a cost-effective alternative to the current standard of care in place at community level for at-risk children exposed to tuberculosis. It is therefore recommended that the tool be used incrementally on a bigger scale, until such time that sufficient evidence has been generated to support widespread implementation.

Tuberculosis is an ancient infectious disease and a leading cause of death globally. Preclinical research is important for defining drugs and regimens which should be carried forward to human studies. This thesis aims to characterize the population pharmacokinetics and exposure-response relationships of anti-tubercular drugs alone and in combinations, and to suggest experimental designs for preclinical settings. The population pharmacokinetics of rifampicin, isoniazid, ethambutol and pyrazinamide were described for the first time in two mouse models. This allowed for linking the population pharmacokinetic model to the Multistate Tuberculosis Pharmacometric (MTP) model for biomarker response, which was used to characterize exposure-response relationships in monotherapy. Pharmacodynamic interactions in combination therapies were quantitatively described by linking the MTP model to the General Pharmacodynamic Interaction (GPDI) model, which provided estimates of single drug effects together with a quantitative model-based evaluation framework for evaluation of pharmacodynamic interactions among drugs in combinations. Synergism (more than expected additivity) was characterized between rifampicin and ethambutol, while antagonism (less than expected additivity) was characterized between rifampicin and isoniazid in combination therapies. The new single-dose pharmacokinetic design with enrichened individual sampling was more informative than the original design, in which only one sample was taken from each mouse in the pharmacokinetic studies. The new oral zipper design allows for informative pharmacokinetic sampling in a multiple-dose administration scenario for characterizing pharmacokinetic-pharmacodynamic relationships, with similar or lower bias and imprecision in parameter estimates and with a decreased total number of animals required by up to 7-fold compared to the original design. The optimized design for assessing pharmacodynamic interactions in the combination therapies, which was based on EC20, EC50 and EC80 of the single drug, provided lower bias and imprecision than a conventional reduced four-by-four microdilution checkerboard design at the same total number of samples required, which followed the 3Rs of animal welfare. In summary, in this thesis the population pharmacokinetic-pharmacodynamic models of first-line drugs in mice were characterized through linking each population pharmacokinetic model to the MTP model. Pharmacodynamic interactions were quantitatively illustrated by the MTP-GPDI model. Lastly, experimental designs were optimized and recommended to both pharmacokinetic and pharmacodynamic studies for preclinical settings.

With approximately nine million new cases and the attributable cause of death of an estimated two millions people every year there is an urgent need for new and effective drugs and treatment regimens targeting tuberculosis. The tuberculosis drug development pathway is however not ideal, containing non-predictive model systems and unanswered questions that may increase the risk of failure during late-phase drug development. The aim of this thesis was hence to develop pharmacometric tools in order to optimize the development of new anti-tuberculosis drugs and treatment regimens. The General Pulmonary Distribution model was developed allowing for prediction of both rate and extent of distribution from plasma to pulmonary tissue. A distribution characterization that is of high importance as most current used anti-tuberculosis drugs were introduced into clinical use without considering the pharmacokinetic properties influencing drug distribution to the site of action. The developed optimized bronchoalveolar lavage sampling design provides a simplistic but informative approach to gathering of the data needed to allow for a model based characterization of both rate and extent of pulmonary distribution using as little as one sample per subject. The developed Multistate Tuberculosis Pharmacometric model provides predictions over time for a fast-, slow- and non-multiplying bacterial state with and without drug effect. The Multistate Tuberculosis Pharmacometric model was further used to quantify the in vitro growth of different strains of Mycobacterium tuberculosis and the exposure-response relationships of three first line anti-tuberculosis drugs. The General Pharmacodynamic Interaction model was successfully used to characterize the pharmacodynamic interactions of three first line anti-tuberculosis drugs, showing the possibility of distinguishing drug A’s interaction with drug B from drug B’s interaction with drug A. The successful separation of all three drugs effect on each other is a necessity for future work focusing on optimizing the selection of anti-tuberculosis combination regimens. With a focus on pharmacokinetics and pharmacodynamics, the work included in this thesis provides multiple new methods and approaches that individually, but maybe more important the combination of, has the potential to inform development of new but also to provide additional information of the existing anti-tuberculosis drugs and drug regimen.

Como entre 25-50% dos isolados de Mycobacterium tuberculosis resistentes à INH não apresentam mutações nos genes katG, inhA, ahpC e kasA que possam justificar sua resistência, foi proposta a influência de mutações específicas no gene nat nos mecanismos de resistência e atividade da NAT. Todos os isolados obtidos (n=125) foram identificados e caracterizados através da amplificação pela PCR da IS6110 e por MIRU-VNTR, respectivamente. A determinação da concentração inibitória mínima (CIM) foi realizada pelo método REMA. Após triagem de mutações nos genes caracteristicamente envolvidos com resistência pela PCR-SSCP, seguida de seqüenciamento de DNA, foram selecionados 45 isolados para o estudo de mutações específicas (pela PCR e sequenciamento) e expressão gênica do mRNA do gene nat através da RT-PCR em tempo real. Confirmou-se que mutação no gene katG é a mais correlacionada com a resistência à INH, pois 68,4% das cepas resistentes apresentaram mutação neste gene. Mutações na região promotora do gene inhA, na região intergênica oxyR-ahpC e no gene kasA foram encontradas em 8,8%, 5,6% e 21,6% dos isolados, respectivamente. Mutações no gene nat, das quais 4 não haviam sido descritas previamente, foram encontradas em 40,0% dos isolados. Apesar dessas mutações causarem alterações na proteína, não foi observada uma relação direta com aumento na CIM. Também não foi observada relação entre a variação da expressão do mRNA do gene nat com os valores de CIM e com o número de mutações, tanto específicas do gene nat como em outros genes caracteristicamente relacionados com resistência à INH. / Since around 25-50% of the Mycobacterium tuberculosis strains resistant to INH do not present any mutation in katG, inhA, ahpC and kasA genes that could explain their resistance, we proposed to evaluate the influence of specific mutations in the nat gene in the mechanisms of resistance and in the activity of NAT. All strains were identified and characterized molecularly by the amplification by PCR of the IS6110 region and by MIRU-VNTR, respectively. The minimal inhibitory concentration (MIC) was performed using the REMA method. After screening of mutations in the resistant-related genes by PCR-SSCP followed by DNA sequencing, 45 strains were selected to be evaluated for specific mutations (by PCR and sequencing) and mRNA expression of nat by real time RT-PCR. It was showed that mutations in the katG gene were the most frequent and related to INH resistance since 68.4% of all resistant strains presented mutation in this gene. Mutations in the promoter region of inhA gene, oxyR-ahpC intergenic region and kasA gene were found in 8.8%, 5.6% and 21.6% of the strains, respectively. Mutations in the nat gene, four of them not previously described, were found in 40.0% of the strains. Although those mutations influence in the protein produced it was not observed a direct relation in an increase in CIM. It was also noted no relation between the expression of mRNA of nat gene neither with the MIC values nor with the number of mutations, both specific of nat gene as well in the other genes characteristically related to INH resistance.

Recomendações para rastreamento de Tuberculoses Latente (TBL) em pacientes que receberão tratamento com antagonistas do TNF-alfa (anti- TNF) permanecem controversas para regiões endêmicas Objetivo: Esse estudo buscou demonstrar a eficácia em longo prazo do rastreamento e tratamento da TBL em pacientes portadores de Artrite Reumatoide (AR) recebendo anti-TNF. Métodos: 202 pacientes com AR, antes do início do anti-TNF, foram rastreados para TBL por meio do teste tuberculínico (TT), Radiografia de tórax (RX) e história de prévia de exposição à tuberculose (EXP). Todos os pacientes foram seguidos com intervalos de um a três meses. Resultados: 85 pacientes (42%) foram tratados com um único agente anti-TNF e 117 pacientes (58%) mudaram de anti-TNF uma ou duas vezes. O rastreamento para TBL foi positivo em 66 pacientes, 44 apresentaram TT positivo, 23 apresentavam história de exposição (EXP), e 14, alterações radiográficas (RX). EXP isoladamente foi responsável por 14 diagnósticos em pacientes TT negativos. Pacientes portadores de TBL receberam tratamento com Isoniazida (300 mg/dia por seis meses) e nenhum deles desenvolveu TB. Durante os seguimentos, o TT foi repetido em 51 pacientes. A conversão foi observada em cinco: três foram diagnosticados com TBL e dois com TB ativa (14 e 36 meses após receber terapia anti-TNF), sugerindo nova exposição a TB. Conclusão: O rastreamento e tratamento da TBL antes do início da terapia com anti-TNF é efetiva em regiões endêmicas, e reforça a relevância da história de contato com TB para o diagnóstico da TBL em pacientes com AR / Recommendations for screening of latent tuberculosis infection (LTBI) in patients eligible for anti-TNF agents remain unclear in endemic regions. Objective: This study aimed to evaluate the long-term efficacy of LTBI screening/treatment in patients with rheumatoid arthritis (RA) receiving TNF blockers. Design: 202 RA patients were screened for LTBI prior to receiving anti-TNF treatment, by means of tuberculin skin test (TST), chest radiography (X-Ray), and history of tuberculosis exposure (EXP). All subjects were regularly followed at 1- to 3-month intervals. Results: Eighty-five patients (42%) were treated with a single anti-TNF agent, and 117 patients (58%) switched anti-TNF agents once or twice. LTBI screening was positive in 66 patients, 44 presented positive TST, 23 had a history of EXP, and 14, abnormal X-Ray. Exposure alone accounted for LTBI diagnosis in 14 patients with negative TSTs. LTBI patients were treated with Isoniazid (300 mg/day during six months) and none developed TB. During follow up, TST was repeated in 51 patients. Conversion was observed in five: three were diagnosed with LTBI and two with active TB (14 and 36 months after receiving anti-TNF therapy, suggesting new TB exposure). Conclusion: LTBI screening and treatment prior to anti-TNF treatment is effective in endemic areas and reinforces the relevance of contact history for diagnosing LTBI in RA patients

Os métodos termo-analíticos são ferramentas úteis na avaliação da compatibilidade entre fármacos e adjuvantes, com destaque à calorimetria exploratória diferencial. Neste trabalho foram avaliados a compatibilidade e o comportamento térmico entre a isoniazida e adjuvantes tecnológicos primários usualmente empregados em formas farmacêuticas sólidas. A compatibilidade foi examinada por meio da preparação de misturas físicas binárias do tipo fármaco/adjuvante. Foi investigada também a influência da granulação por via úmida e do processo de compactação para as misturas de isoniazida e adjuvantes com função de material de enchimento e carga e deslizante. A isoniazida apresentou um comportamento térmico não encontrado na literatura. Os adjuvantes avaliados foram: ácido esteárico, amido, celulose microcristalina, crospovidona, croscarmelose sódica, dióxido de silício coloidal estearato de magnésio, glicolato de amido sódico, hipromelose, lactose, manitol, polidona e talco. Para as misturas físicas, a maioria dos adjuvantes mostrou-se compatível com o fármaco em questão. Foram verificadas interações com o ácido esteárico, o glicolato de amido sódico, a lactose, o manitol e a povidona. A isoniazida mostrou a formação de uma mistura eutética com o manitol e de interação química com a lactose. A agregação por via úmida e o processo de compactação não mostraram influências adicionais na compatibilidade das misturas avaliadas. Os resultados observados foram confirmados por métodos não-térmicos como difratometria de raios X, espectroscopia de infravermelho e ressonância nuclear magnética. / Thermo-analytical methods, and specially Differential Scanning Calorimetry, are useful support for the evaluation of compatibility between drug substances and pharmaceutical excipients. In this work were studied the compatibility and the thermal behavior of isoniazid and pharmaceutical excipients, commonly used for the formulation of solid dosage forms. Colloidal silicon dioxide, corn starch, crospovidone, hypromellose, lactose, magnesium stearate, mannitol, microcrystalline cellulose, povidone, sodium croscarmellose, sodium starch glycolate, stearic acid and talc were the excipients employed in these experiments. The compatibility was analyzed testing binary physical drug/excipient admixtures. The effect of wet granulation and compression was also investigated, in this case especially between isoniazid, fillers and lubricant. For almost all excipients no incompatibilities with isoniazid were observed. Interactions were detected when the drug substance was added to stearic acid, sodium starch glycolate, lactose, mannitol and povidone. Isoniazid formed a euthetic mixture with mannitol, whereas a possible chemical reaction occurred between isoniazid and lactose. Wet granulation and compaction of the tested admixtures did not affect the results observed above. These observations were confirmed by non-thermal techniques, such as X-Ray diffractometry, infrared spectroscopy and nuclear magnetic resonance.

FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / Baixas concentraÃÃes sÃricas de drogas antituberculose podem ser causa da resistÃncia de Mycobacterium tuberculosis Ãs drogas utilizadas para tratamento, a qual à mais freqÃente em pacientes em tratamento irregular, mas pode ser verificada em pacientes em tratamento diretamente observado. Os objetivos desse estudo foram avaliar a permeabilidade intestinal e a biodisponibilidade de rifampicina, isoniazida e pirazinamida em pacientes com tuberculose pulmonar ativa. Realizou-se estudo transversal controlado. No perÃodo entre julho de 2004 e dezembro de 2005 foram selecionados 56 pacientes consecutivos com tuberculose pulmonar ativa, atendidos no Centro de SaÃde Carlos Ribeiro em Fortaleza, Cearà e 29 controles sadios recrutados entre profissionais de saÃde, seus familiares e vizinhos para avaliaÃÃo da permeabilidade intestinal. Foram coletadas informaÃÃes sociodemogrÃficas e exames bioquÃmicos e realizou-se o teste de lactulose/manitol de todos. Os primeiros 30 casos de tuberculose e os 29 controles dessa amostra foram selecionados para a avaliaÃÃo da biodisponibilidade sÃrica de rifampicina, isoniazida e pirazinamida em amostras coletadas duas horas e seis horas depois da ingestÃo. A mÃdia de idade dos casos foi de 39,2  15 anos e a dos controles 34  11,0 (p=0,61). Eram do sexo masculino 71 % dos casos e 66% dos controles (p=0,57). O peso mÃdio dos casos (52,4  6,3 kg) foi significativamente menor do que o dos controles (71,1  14,0 kg) (p=0,014). Verificou-se menor excreÃÃo de lactulose entre os casos (mediana de 0,1721%; variando de 0,0-5.0139%) do que entre os controles (0,4301%; variando de 0,0-2,064) (p=0,049%); a excreÃÃo de manitol entre os casos foi 17,9910% (1,9567-71,5446%) e entre controles foi de 24,3899% (1,3883-63,0539%) (p=0,147); a relaÃÃo lactulose/manitol foi de 0,0095 (0,0-0,0759%) entre os casos e 0,0136 (0,0-0,0136%) entre os controles (p=0,018). A concentraÃÃo sÃrica mÃxima de rifampicina teve mÃdia de 1,46  0,72 Âg/ml nos casos e de 6,69  3,07 Âg/ml nos controles (p<0,001); a de isoniazida foi 2,62  1,53 Âg/ml entre os casos e 1,98  0,76 Âg/ml entre os controles (p=0,057) e a de pirazinamda foi de 44,10  10,40 Âg/ml entre os casos e 36,32  12,02 Âg/ml entre os controles (p=0,007). Quatro (13,3%) casos nÃo chegaram a alcanÃar os limites mÃnimos das concentraÃÃes normais esperadas de nenhuma das drogas de primeira linha para o tratamento da tuberculose; 21 (70,0%) alcanÃaram essa concentraÃÃo sÃrica apenas para uma droga (pirazinamida) e cinco (16,7%) apenas para duas drogas (pirazinamida e isoniazida). Nenhum caso alcanÃou as concentraÃÃes sÃricas normais esperadas para as trÃs drogas, simultaneamente. Em conclusÃo, observou-se reduÃÃo da absorÃÃo paracelular entre os pacientes com tuberculose bem como mà absorÃÃo intestinal de rifampicina e isoniazida. Estes resultados sugerem a necessidade da avaliaÃÃo de medidas para reduzir a mà absorÃÃo intestinal de drogas e evitar o retardo ou a impossibilidade de cura da doenÃa, bem como o risco de multirresistÃncia / Reduced antituberculosis drugs concentrations are associated with Mycobacterium tuberculosis resistance, mostly in patients in irregular but also in directly observed treatment. This study aims to evaluate intestinal permeability and bioavailability of rifampin (R), isoniazid (I) and pyrazinamide (P) in patients with active pulmonary tuberculosis. A controlled cross sectional study evaluated intestinal permeability from 56 consecutive active pulmonary tuberculosis (TB) patients who attended Carlos Ribeiro Health Unit in Fortaleza, CearÃ, northeast of Brazil, from July 2004 to December 2005. The Thirty who first came were selected to have R, I and P serum concentration dosed. Twenty nine healthy controls were select among health professionals, their relatives and neighboring. To access intestinal permeability lactulose/manitol (L/M) test was performed by HPLC in urine samples collected during five hours. To access bioavailability two blood samples were collect at 2 and 6 hours after drug ingestion. Demographic information was recorded from all volunteers. Mean age was 39.2  15 years in cases and 34  11.0 in controls (p=0.61); 71.4% cases and 65.5% controls were men (p=0.57). Lactulose urinary excretion was significantly lower in TB patients (median 0.1721%; range 0.0-5.0139) than in controls (median 0.4301%; range 0.2125-2.064) (p=0.0194); median manitol excretion in cases was 17.9910% (1.9567-71.5446) and in controls, 24.39894% (range 1.3883-63.0539) (p=0.147) and the lactulose/manitol ratio was of 0.0095 (range 0.0-0.0759) in cases and 0.0153 (0.0-0.0136) in controls (p=0.0698). Maximum means seric rifampin concentration in cases was1.46  0.72 Âg/ml and in controls, 3.07  6.69Âg/ml (p<0.001); maximum means seric isoniazid concentration was 2.62  1.53 Âg/ml in cases and 0.76  1.98 Âg/ml in controls (p=0.057); maximum means seric pirazinamide concentratio was 44.10  10.40 Âg/ml in cases and 12.02  36.32 Âg/ml in controls (p=0.007). Four cases (13.3%) had all tested drugs serum concentrations under expected normal; 21/30 (70.0%) had expected normal concentrations only for one drug (pyrazinamide) and 5/30 (16.7%) for 2 drugs only (pirazinamide and isoniazid). None of the cases had expected concentration levels for all 3 drugs, simultaneously. In conclusion, there was lesion in the functional intestinal barrier and malabsorption for rifampin and isoniazid in active pulmonary TB patients suggesting it is necessary a deeper evaluation of measures to reduce malabsorption, since only these drugs are used during last the four months of treatment