Major depressive disorder (MDD) is a widespread psychiatric disorder that affects millions of people worldwide and is hypothesized to occur due to impairments in several neurotransmitter systems, including the monoaminergic and glutamatergic neurotransmitter systems. Antidepressant medications targeting multiple monoamine neurotransmitters have been shown to be effective for the treatment of depression. Racemic amisulpride is an atypical antipsychotic that has been used at low doses to treat dysthymia, a mild form of depression, and functions as an antagonist at DA2/3, 5-HT2B, and 5-HT7 receptors. Recent preclinical studies have suggested that the S(+) isomer may be more critical for amisulpride’s antidepressant-like effects; however, this interpretation has not been fully characterized in comparison to the R(-) isomer. The glutamatergic system also has been shown to play a critical role in alleviating depression. Several studies have demonstrated that the noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist ketamine produces rapid and sustained antidepressant-like effects in clinical trials; however, few studies have examined the degree to which ketamine’s isomers contribute to antidepressant-like effects. Fully characterizing these differences in a preclinical model of depression may offer important insight into the role of these neurotransmitter systems on depression. The present study used a 72-sec differential-reinforcement-of-low-rate (DRL) task to assess the antidepressant-like effects of amisulpride, ketamine, and their isomers in mice. The DRL 72-sec task has shown to be a reliable and sensitive screen for drugs that possess antidepressant-like activity as reflected by an increase in the number of reinforcers, a decrease in the number of responses, and a right-ward shift in the interresponse time distributions (IRTs; i.e. the elapsed time between two successive responses). For comparison, the effects of the tricyclic antidepressant imipramine and the N-methyl-D-aspartate antagonist MK-801 as positive and negative controls, respectively, were determined. Consistent with previous findings, we hypothesized that amisulpride and S(-)-amisulpride, but not R(+)-amisulpride, would produce antidepressant-like effects, and all formulations of ketamine would produce antidepressant effects. Racemic amisulpride and S(-)-amisulpride, but not R(+)-amisulpride, produced an antidepressant-like effect, evidenced by a significant increase in the number of reinforcers and a significant decrease in the number of responses. Racemic ketamine and R(-)-ketamine significantly increased the number of reinforcers and decreased the number of responses, while S(+)-ketamine significantly increased the number of reinforcers, but did not decrease the number of responses (at the doses tested). Overall, these results indicate that the racemic formulations of amisulpride and ketamine, S(-)-amisulpride, and both ketamine isomers demonstrate antidepressant-like effects as assessed in the DRL task and may be useful in a clinical context. If either of the ketamine isomers can be shown to produce fewer psychotomimetic effects in humans, then the isomers may offer a significant clinical advantage over the parent compound ketamine. Regarding amisulpride, the present results demonstrate that the S(-) isomer, but not the R(+) isomer, possess antidepressant-like activity similar to racemic amisulpride.

The enantioanalysis of compounds of clinical and pharmaceutical became increasingly important because the enantiomers of the same substance may be markers for different disease or are having a different pathway in the body. The utilization of enantioselective, potentiometric membrane electrodes made the assay of a single enantiomer easier and faster. Also the reliability of the analytical information is higher than that obtained using chromatographic techniques. The proposed electrodes are made by mixing graphite powder with paraffin oil to give carbon paste, which is modified by the addition of a chiral selector (e.g., cylodextrins, maltodextrins, macrocyclic antibiotics and fullerenes). This design is reliable. The high sensitivity, selectivity, enantioselectivity, accuracy and precision made them suitable to be used for the enantioanalysis of different compounds of clinical and pharmaceutical importance (e.g., L-histidine, L-cysteine and R-clenbuterol) in pharmaceutical tablets, and/or serum and urine samples. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Chemistry / unrestricted

(EN) The dissertation thesis is focused on the research and characterization of retention and enantiorecognition mechanisms of chiral stationary phases based on derivatized polysaccharides. The separation systems with a variety of modern stationary phases (both achiral and chiral) were characterized in detail to provide a comprehensive view of the interactions participating in the separation process. The study of the retention/separation behavior significantly facilitates the development and the optimization of new enantioselective methods for a wide variety of compounds. The work deals with the comparison of enantioselective performance of polysaccharide-based chiral stationary phases. The objectives are to show the differences of separation behavior among these chiral stationary phases, as they differ by the nature of the polysaccharide backbone (amylose versus cellulose), by binding of chiral polymer to silica support (coated versus immobilized stationary phase) and by the phenyl moiety in the reversed and normal phase HPLC. In both separation modes amylose-based chiral stationary phases exhibited higher enantioselectivity, especially for acidic and bifunctional analytes. Chiral stationary phases based on derivatized cellulose showed higher enantiodiscrimination potential for basic analytes....

No / Synthesis of a melatonin agonist for treatment of sleep disorders produced a pair of enantiomers, of which one is biologically active. Two polymorphs were discovered using the inactive enantiomer, conserving the active enantiomer for toxicological testing. Later studies with the active enantiomer yielded only the metastable form, despite more than 1000 attempts to isolate the stable form. The difficulty is surprising, since the stable form is favored by 0.7 kcal mol–1, which is toward the extreme for stability differences between organic polymorphs. Study of individual enantiomers allowed the phase behavior of polymorphs of greatly different energy to be examined without interconversion. A number of unusual features are noted. After the stable polymorph of the inactive enantiomer was nucleated, the metastable form became very difficult to isolate. The metastable form converts into a less soluble monohydrate structure in water, whereas the stable polymorph does not due to its reduced activity. Both chiral polymorphs are denser than the racemic crystalline form at low temperature, the stable form being at the extreme for chiral-racemic pairs. Free energy-temperature relations predict “spontaneous resolution” of the racemic crystalline form into a conglomerate mixture of stable polymorph at low temperature. The unusual characteristics of the system are explained by hydrogen bonding and conformational flexibility of the molecule. Ab initio calculations aid in understanding the relative contributions of these interactions to the lattice energies and the role that conformational energy differences play in the polymorphic stability. This system highlights the importance of the creation of the very first nuclei of a crystalline form. The reluctance of the stable form to nucleate is attributed to a large energy difference between polymorphic forms. The large interfacial tension for primary nucleation reduces the probability of forming clusters of size sufficient for favorable growth in the absence of heterogeneous nucleation. This study highlights how nucleation of a new form can revise the readily “accessible” region of a compound’s crystal form landscape.

Orientador: Everson Alves Miranda / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-04T07:13:28Z (GMT). No. of bitstreams: 1 Barros_GeorgiadeOliveiraFigueiredo_M.pdf: 2282903 bytes, checksum: b104323f697a813ec6af57b15ba7b95b (MD5) Previous issue date: 2005 / Resumo: A separação de enantiômetros em altos níveis de pureza enantiomérica é atualmente um requerimento da industria farmacêutica. No entanto, altas purezas estão sendo alcançadas neste sistema com comprometimento da produtividade. O acoplamento do leito móvel simulado (LSM) a uma etapa de cristalização pode resultar num processo de maior produtividade global . A escolha do método de cristalização para a resolução de misturas racêmicas por cristalização é dependente do tipo de cristal (conglomerado ou composto racêmico) e da localização do ponto eutético no diagrama de solubilidade. O ponto eutético difine a mínima puraza enantiomérica que deve ser fornecida pelo LMS para assegurar que a cristalização irá produzir somente um dos enantiômeros puros. A cetamina é um anstésico que possui um isômero R com indesejáveis efeitos colaterais. O objetivo deste trabalho é trabalho é o desenvolvimento de conhecimento básico (identificação do tipo de racemato e seu ponto eutético no diagrama de solubilidade) para o acolplamento do LMS a uma etapa de cristalização a fim de produzir o isômero S da cetamina em pureza enantiomérica e produtividade alta. Para caracterizar a natureza cristalina da cetamina, diração de raios-X e espectroscopia de infravermelho da mistura racêmica e dos enantilômero puros foram realizados e as curvas de solubilidade em função da temperatura foram determinadas...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The resolution of enantiomers to high levels of enantiomeric purity is presntly a requeriment in the pharmaceutical industry. However, high, purities are reached with this system at the expenses of productivity. Coupling of simulated moving bed (SMB) to a crystallization step can result in a process whith a overall higher productivity. The choise ofcristallization method for the resolution of racemic mixtures is dependent on the eutetic point on the solubility diagram. Eutetic point is the minimum enantiomeric purity that has to be delivered by the SMB to assure that crystallization will produce just one pure isomer. Ketamine is a anesthetic that has a R-isomer with undesirable side-effect. The objective of this work was development of basic knowlwdge for a process (identification of the type of racemate and its eutetic point in the solubility diagram) coupling the SMB to a crystallization step in order to produce the S-isomer of ketamine at high enantiomeric purity and productivity. To characterize the crystalline nature of ketamine, X-ray diffraction and infrared spectroscopy of the racemic mixture and pure enantiomers were performed between powder x-ray pattems, infrared spectra, and solubility curve slopes of the pure enantiomers and racemic mixture indicated racemic compound formation...Note: The complete abstract is available with the full electronic digital thesis or dissertations / Mestrado / Desenvolvimento de Processos Biotecnologicos / Mestre em Engenharia Química

Since the tragedy of the drug Thalidomide® in the late 1950 to early 1960’s, chirality has been recognized as an important aspect that must be controlled in the drug development process in the pharmaceutical industry. Since then, there has been a considerable movement towards single enantiomer drugs. This demand has presented many challenges for the synthetic organic chemist. Chiral catalysts offer one solution to this problem, as they afford the unique ability to preferentially synthesize one enantiomer. Unfortunately, the design of new chiral catalysts is often empirical, with luck and trial and error necessary due to factors that govern enantioselectivity. Therefore, it would be highly beneficial to develop a method that is capable of screening multiple chiral catalysts early in the catalyst development cycle. Using a modified ion-trap mass spectrometer, the chiral environment of various chiral catalysts may be examined, free from solvent and ion-pairing affects. Thus, the catalyst’s inherent asymmetric environment (enantioselectivity) may be probed using simple chiral molecules, including alcohols, ethers, and epoxides of various steric demands. Using these probes, various C2-symmetric bis-oxazolines and di-imines catalysts were examined. Use of the binaphthyl-based diamine, BINAM, condensed with various 3,5-disubstituted benzaldehydes, provided selectivity close to the privileged catalyst, bis-oxazoline. In general, the chiral probes 1-phenyl-2-propanol, 1-mehtoxyethylbenzene, and styrene oxide offer the best look at the catalyst’s enantioselectivity potential. With the use of the ion-trap mass spectrometer as a mass filter, the purity of the catalyst is not paramount, thus, multiple catalysts may be screened simultaneously, with the constraint that the catalysts must be of different m/z. This thesis presents results found during the exploration of various C2 and C1-symmetric chiral catalysts, in the development of the new chiral screening method utilizing various chiral probes.

A venlafaxina é um fármaco usado no tratamento da depressão e dos transtornos de ansiedade generalizada. É disponível na clínica na forma de mistura racêmica dos enantiômeros S-(+) e R-(-) em formulação de liberação controlada. O enantiômero S-(+) inibe a recaptação da serotonina, enquanto o enantiômero R-(-) inibe a recaptação da serotonina e da norepinefrina. A venlafaxina é biotransformada pelo CYP2D6 e CYP2C19 em seu principal metabólito, O-desmetilvenlafaxina, o qual apresenta atividade farmacológica semelhante à venlafaxina. Outros metabólitos da venlafaxina, dependentes do CYP3A4, incluem a N-desmetilvenlafaxina e a N,O-di-desmetilvenlafaxina. A absorção e a distribuição da venlafaxina são moduladas pela ação da glicoproteina-P. O nifedipino, um fármaco da classe dos inibidores dos canais de cálcio, é descrito como inibidor da glicoproteina-P. O presente estudo investiga a influência do nifedipino na disposição cinética e no metabolismo da venlafaxina em voluntários sadios caracterizados como portadores de atividade normal do CYP3A (omeprazol como fármaco marcador) e fenotipados como metabolizadores rápidos do CYP2C19 (omeprazol como fármaco marcador) e do CYP2D6 (metoprolol como fármaco marcador). Os voluntários investigados receberam, em estudo cruzado e randomizado, dose única oral de 150 mg de venlafaxina racêmica (Fase 1) e 40 mg de nifedipino associada com dose única oral de 150 mg de venlafaxina racêmica (Fase 2). Foram coletadas amostras seriadas de sangue até 72 horas após a administração dos fármacos para o estudo farmacocinético. As concentrações plasmáticas dos enantiômeros da venlafaxina e de seus metabólitos foram determinadas por LC-MS/MS utilizando a coluna Chirobiotic V com fase móvel constituída de mistura de metanol: solução aquosa de acetato de amônio 15 mmol/L pH 6,0 (80:20, v/v). A farmacocinética da venlafaxina mostrou-se enantiosseletiva com acúmulo plasmático (AUC 526,0 vs 195,7 ng.h/mL) e menores valores de clearance (Cl/f 142,67 vs 408,01 L/h) para o enantiômero S-(+). A disposição cinética do metabólito ativo O-desmetilvenlafaxina apresentou enantiosseletividade apenas no parâmetro concentração plasmática máxima com observação de maiores valores para o enantiômero R-(-) (Cmax 69,33 vs 56,94 ng/mL). A disposição cinética da N,O-di-desmetilvenlafaxina também mostrou-se enantiosseletiva apenas para o parâmetro concentração plasmática máxima, mas com observação de maiores valores para o enantiômero S-(+) (Cmax 7,08 vs 4,61 ng/mL). A administração de dose única oral de 40 mg de nifedipino não alterou a farmacocinética de ambos os enantiômeros da venlafaxina e de seus metabólitos O-desmetilvenlafaxina e N,O-di-desmetilvenlafaxina, seja utilizando teste estatístico não paramétrico (teste de Wilcoxon para dados pareados, p < 0,05), seja avaliando o IC 90% das razões das médias geométricas de AUC e Cmax (Fase 2/Fase 1). Os dados obtidos evidenciam que o nifedipino na dose de 40 mg não age como um inibidor da P-gp / Venlafaxine is a drug used to treat depression and generalized anxiety disorders. It is available in clinical practice in the form of a racemic mixture of S-(+) and R-(-) enantiomers, in controlled release formulation. The S-(+) enantiomer inhibits the reuptake of serotonin, while the R-(-) enantiomer inhibits the reuptake of both serotonin and norepinephrine. Venlafaxine is biotransformed by CYP2D6 and CYP2C19 in its major metabolite, O-desmethylvenlafaxine, which has similar pharmacological activity when compared to venlafaxine. Other metabolites of venlafaxine, dependent of CYP3A4, include N-desmethylvenlafaxine and N, O-di-desmethylvenlafaxine. The absorption and distribution of venlafaxine are modulated by the action of P-glycoprotein. Nifedipine, a calcium channel blocker drug, is described as an inhibitor of P-glycoprotein. The present study investigates the influence of nifedipine on the kinetic disposition of venlafaxine enantiomers and its metabolites in healthy volunteers characterized as having normal activity of CYP3A (omeprazole as a probe drug) and phenotyped as rapid metabolizers of CYP2C19 (omeprazole as a probe drug) and CYP2D6 (metoprolol as a probe drug). The enrolled volunteers received, in a randomized, two-way study, a single 150 mg oral dose of racemic venlafaxine (Phase 1) and 40 mg oral dose of nifedipine associated with a single 150 mg oral dose of racemic venlafaxine (Phase 2). Serial blood samples were collected until 72 hours after drug administration to the pharmacokinetic study. Plasma concentrations of venlafaxine enantiomers and its metabolites were determined by LC-MS/MS using a Chirobiotic V column and a mobile phase constituted of methanol: aqueous 15 mmol/L ammonium acetate solution pH 6.0 (80:20, v/v). The venlafaxine pharmacokinetics is enantioselective with plasma accumulation (AUC 526.0 vs 195.7 ng h/mL) and lower clearance values (CL/f 142.67 vs 408.01 L/h) for the S-(+) enantiomer. The kinetic disposition of the active metabolite O-desmethylvenlafaxine exhibits enantioselectivity only in the maximum plasma concentration parameter with higher values for the R-(-) enantiomer (Cmax 69.33 vs 56.94 ng/mL). The kinetic disposition of N,O-di-desmethylvenlafaxine is also enantioselective only for the maximum plasma concentration parameter, but with higher values for the S-(+) enantiomer (Cmax 7.08 vs 4.61 ng/ml). Administration of a 40 mg single oral dose of nifedipine do not alter the pharmacokinetics of both enantiomers of venlafaxine and its metabolites O-desmethylvenlafaxine and N,O-di-desmethylvenlafaxine, using non-parametric statistical test (Wilcoxon test for paired data, p <0.05), or evaluating the 90% CI of the AUC and Cmax geometric mean ratios (Phase 2/Phase 1). The obtained data show that nifedipine in a 40 mg oral dose does not act as a P-gp inhibitor.

O citalopram (CITA), inibidor seletivo da recaptação da serotonina, é disponível na clínica como mistura racêmica dos enantiômeros (+)-(S) e (-)-(R) ou como enantiômero puro (+)-(S)-CITA. O CITA é metabolizado pelo CYP2C19, CYP2D6 e CYP3A ao desmetilcitalopram (DCITA) e pelo CYP2D6 ao didesmetilcitalopram. O estudo investiga a influência de inibidores enzimáticos no metabolismo enantiosseletivo do CITA em ratos e em voluntários sadios. Os ratos machos Wistar (n=6 para cada grupo) foram tratados com dose única de 20 mg/Kg de CITA (grupo controle) ou pré-tratados com 80 mg/Kg de quinidina (grupo quinidina), 10 mg/Kg de fluvoxamina (grupo fluvoxamina) ou 50 mg/Kg de cetoconazol (grupo cetoconazol). As amostras de sangue foram colhidas dos ratos até 20 h após a administração do CITA. Os voluntários sadios fenotipados como metabolizadores extensivos (EM) do CYP2C19 (omeprazol como fármaco marcador), EM do CYP2D6 (debrisoquina como fármaco marcador) e com atividade normal do CYP3A (midazolam como fármaco marcador) receberam dose única p.o. de 20 mg de CITA racêmico associado ou não ao omeprazol (20 mg/dia durante 18 dias). Os enantiômeros do CITA e do DCITA foram analisados no sistema LC-MS/MS, com a coluna quiral Chiralcel OD-R e fase móvel constituída por acetonitrila:metanol:água (30:30:40 v/v/v) contendo 0,05 % de dietilamina. O método foi linear no intervalo de concentrações de 0,1 20 ng de cada enantiômero do CITA e DCITA/mL de plasma humano e de de 0,1 500 ng de cada enantiômero do CITA e DCITA/mL de plasma de rato. Os coeficientes de variação obtidos nos estudos da precisão e a inexatidão foram inferiores a 15 % para plasma humano e plasma de ratos. A disposição cinética do CITA é enantiosseletiva nos ratos dos grupos controle (razão de AUCS/R de 0,4), quinidina (razão de AUCS/R de 0,5) e cetoconazol (razão de AUCS/R de 0,8). A inibição do CYP2D pela quinidina resultou em inibição do metabolismo do CITA e do DCITA de maneira não enantiosseletiva. A inibição do CYP2C pela fluvoxamina e do CYP3A pelo cetoconazol resultou em inibição somente do metabolismo do (+)-(S)-CITA. A disposição cinética do CITA em voluntários sadios é enantiosseletiva na ausência de tratamento com o omeprazol com observação de maior proporção plasmática do enantiômero (-)-(R)-CITA. A razão de AUCS/R obtida para o CITA foi de 0,56 e para o metabólito DCITA foi de 1,06. A administração de CITA racêmico a voluntários sadios em tratamento com o omeprazol exibe perda da enantiosseletividade na farmacocinética do CITA. A razão de AUCS/R foi de 0,96 para o CITA e de 0,92 para o DCITA. A administração de omeprazol em doses múltiplas a voluntários sadios inibe de maneira enantiosseletiva o metabolismo do eutômero (+)-(S)-CITA com aumento das concentrações plasmáticas em aproximadamente 140%. / Citalopram (CITA), a selective serotonin reuptake inhibitor, is available for clinical use as a racemic mixture of the (+)-(S) and (-)-(R) enantiomers or as the pure (+)-(S)-CITA enantiomer. CITA is metabolized by CYP2C19, CYP2D6 and CYP3A to demethylcitalopram (DCITA) and by CYP2D6 to didemethylcitalopram. The present study investigated the influence of enzyme inhibitors on the enantioselective metabolism of CITA in rats and healthy volunteers. Male Wistar rats (n=6 for each group) received a single dose of 20 mg/kg CITA (control group) or were pretreated with 80 mg/kg quinidine (quinidine group), 10 mg/kg fluvoxamine (fluvoxamine group), or 50 mg/kg ketoconazole (ketoconazole group). Blood samples were collected from the animals up to 20 h after the administration of CITA. Healthy volunteers phenotyped as extensive metabolizers of CYP2C19 (omeprazole as marker drug) and of CYP2D6 (debrisoquine as marker drug) and those with normal CYP3A activity (midazolam as marker drug) received a single oral dose of 20 mg racemic CITA combined or not with omeprazole (20 mg/day for 18 days). The CITA and DCITA enantiomers were analyzed by LC-MS/MS using a Chiralcel OD-R chiral column and a mobile phase of acetonitrile:methanol:water (30:30:40, v/v/v) containing 0.05% diethylamine. The method was linear in the concentration range of 0.1-20 ng of each CITA and DCITA enantiomer/mL human plasma and of 0.1-500 ng of each CITA and DCITA enantiomer/mL rat plasma. Accuracy and precision were below the acceptance limits of 15% for human and rat plasma. The kinetic disposition of CITA was enantioselective in rats of the control (AUCS/R ratio = 0.4), quinidine (AUCS/R ratio = 0.5) and ketoconazole (AUCS/R ratio = 0.8) groups. The inhibition of CYP2D by quinidine resulted in the non-enantioselective inhibition of the metabolism of CITA and DCITA. The inhibition of CYP2C by fluvoxamine and of CYP3A by ketoconazole only inhibited the metabolism of (+)-(S)-CITA. The kinetic disposition of CITA in healthy volunteers was enantioselective in the absence of treatment with omeprazole, with the observation of a higher plasma proportion of the (-)-(R)-CITA enantiomer. The AUCS/R ratio was 0.56 for CITA and 1.06 for the DCITA metabolite. The administration of racemic CITA to healthy volunteers treated with omeprazole showed a loss of enantioselectivity in the pharmacokinetics of CITA. The AUCS/R ratio was 0.96 for CITA and 0.92 for DCITA. The administration of multiple doses of omeprazole to healthy volunteers enantioselectively inhibited the metabolism of the (+)-(S)-CITA eutomer, with an approximately 140% increase of plasma concentrations

O nebivolol, um fármaco com quatro centros quirais, está disponível na clínica como mistura racêmica dos isômeros d-nebivolol (SRRR) e l-nebivolol (RSSS). A atividade -adrenérgica do nebivolol reside no isômero d-nebivolol, enquanto o l-nebivolol promove a liberação de óxido nítrico das células endoteliais. O nebivolol é eliminado por metabolismo dependente do CYP2D6. O estudo avalia a farmacocinética e a relação farmacocinética-farmacodinâmica (PK-PD) dos isômeros do nebivolol em voluntários sadios. Foram investigados 15 voluntários sadios (10 homens e 5 mulheres) fenotipados com metoprolol como metabolizadores extensivos (EM, n=13) ou metabolizadores lentos para o CYP2D6 (PM, n=2). Os voluntários sadios foram tratados com dose única oral de 10 mg de nebivolol racêmico. As amostras seriadas de sangue foram coletadas até 48 h após a administração do fármaco. Os isômeros do nebivolol foram resolvidos na coluna Chirobiotic® V e analisados nas amostras de plasma empregando LC-MS/MS. Os parâmetros farmacocinéticos foram calculados por modelo bicompartimental com lag time, empregando o programa WinNonLin. A farmacodinâmica do nebivolol foi avaliada empregando como parâmetro a variação da frequência cardíaca entre os períodos final e anterior ao teste de esforço isométrico durante 2 min utilizando o handgrip a 30% da contratilidade voluntária máxima. A análise PK-PD relacionando o efeito na variação da frequência cardíaca induzida pelo exercício isométrico com as concentrações plasmáticas do isômero d-nebivolol foi avaliada empregando o modelo Emax sigmóide inibitório. A disposição cinética do nebivolol é enantiosseletiva nos voluntários sadios EM, com razões isoméricas de AUCl/ AUCd de 1,41. Os valores de concentração plasmática máxima (1,46 vs 0,79 ng/mL), área sob a curva concentração plasmática versus tempo (6,45 vs 3,99 ng.h/mL), clearance aparente (774,51 vs 1252,70 L/h) e volume de distribuição aparente (10936 vs 19082 L) mostram diferenças com significância estatística (Teste de Wilcoxon, p<0,05) entre os isômeros l-nebivolol e d-nebivolol para os voluntários sadios EM. A disposição cinética do nebivolol não é enantiosseletiva nos voluntários sadios PM investigados, com razões isoméricas de AUCl/AUCd de 0,93 e 0,98. Os valores de clearance aparente obtidos para os voluntários PM (87-350 vs 81-344 L/h, respectivamente para o l-nebivolol e d-nebivolol) são menores do que para os EM (775 vs 1253 L/h). O modelo Emax sigmóide inibitório descreveu a análise PK-PD relacionando o efeito na variação da frequência cardíaca induzida pelo exercício isométrico com as concentrações plasmáticas do isômero d-nebivolol em voluntários sadios EM com valores de Emax de 4,47 bpm (IC 95% 1,37-7,57) e de EC50 de 222,16 pg/mL (IC 95% 96,29-540,60 pg/mL). / Nebivolol is a drug with four chiral centers. It is administered in clinical practice as a racemic mixture of the isomers d-nebivolol (SRRR) and l-nebivolol (RSSS). The - blocking activity of nebivolol is attributed to d-nebivolol, whereas l-nebivolol promotes the release of nitric oxide from endothelial cells. Nebivolol is eliminated by metabolism dependent on CYP2D6. The present study evaluates the pharmacokinetic and pharmacokinetic-pharmacodynamic (PK-PD) of nebivolol isomers in healthy volunteers (10 men and 5 women) phenotyped with metoprolol as extensive metabolisers (EM, n=13) or poor metabolisers for CYP2D6. The healthy volunteers receveid a single oral dose of 10mg of racemic nebivolol. Serial blood samples were collected from 0 to 48 h after the administration of nebivolol. The isomers of nebivolol were analyzed by LC-MS-MS on a Chirobiotic® V column and the pharmacokinetic parameters (bicompartment model, micro, lag time, first order) were calculated by the software Winnonlin. The pharmacodynamic of nebivolol was evaluated using the variation of heart rate as parameter between the end and one minute before the handgrip exercise. Thus, the patients were oriented to conduct the isometric exercise with handgrip for 2 min at 30% of their maximum voluntary contractility. The PK-PD analysis relating the effect on the variation of heart rate induced by the isometric exercise and the plasma concentrations of the isomer d-nebivolol were evaluated using the Inhibitory effect sigmoid Emax model. The kinetic disposition of nebivolol is enantioselective on healthy volunteers EM, with isomeric ratios of AUCl/ AUCd of 0,93 e 0,98. The values of maximum plasma concentration (1,46 vs 0,79 ng/mL), area under the concentration time curve (6,45 vs 3,99 ng.h/mL), apparent clearance(774,51 vs 1252,70 L/h) and volume of distribution (10936 vs 19082 L) show statistically significant differences (p<0.05, Wilcoxon test) between the isomers l-nebivolol and d-nebivolol for the healthy volunteers EM. The kinetic disposition of nebivolol is not enantioselective on the healthy volunteers PM investigated, with isomeric ratios of AUCl/ AUCd of 1,07. The values of apparent clearance obtained for the volunteers pm (87-350 vs 81-344 L/h, respectively to l-nebivolol and d-nebivolol) are smaller than that for EM (775 vs 1253 L/h). The Inhibitory effect sigmoid Emax model described the PK-PD analysis described the effect on the variation of heart rate induced by handgrip isometric exercise with the plasma concentrations of the isomer d-nebivolol in healthy volunteers EM with Emax values of 4,47 bpm (IC 95% 1,37-7,57) and EC50 of 222,16 pg/mL (IC 95% 96,29-540,60 pg/mL).

Os enantiômeros de um fármaco administrado como mistura racêmica, podem manifestar diferentes efeitos farmacológicos e toxicológicos. A fluvastatina (FV), um inibidor da HMG-CoA redutase, é comercializada como mistura racêmica dos enantiômeros (-)-3S,5R e (+)-3R,5S (eutômero) e com eliminação no homem essencialmente dependente do CYP2C9. O metanol, amplamente usado como solvente, combustível e em processos de sínteses, é um inibidor do CYP2C9 em humanos. Diante do exposto, o estudo visou avaliar a influência do metanol na farmacocinética enantiosseletiva da fluvastatina administrada sob forma racêmica a ratos. Foram investigados ratos machos Wistar tratados com dose única de 5 mg/kg de fluvastatina racêmica administrada por gavagem. Os animais foram divididos em três grupos: controle e expostos a metanol em concentrações de 262 mg/m3 e 1048 mg/m3. A exposição ao metanol foi feita em câmara de exposição do tipo apenas pelo nariz, em sessões consecutivas de 6 horas com intervalos de 2 horas, durante o período de 30 horas de coletas seriadas de sangue. Os enantiômeros da FV foram analisados em HPLC com amostrador automático e detecção por fluorescência, operando em 305 nm para excitação e 390 nm para emissão. A análise farmacocinética foi realizada por modelo bicompartimental e cinética de primeira ordem. Os resultados são reportados como medianas, médias e respectivos intevalos de confiança (95%). A farmacocinética da fluvastatina é enantiosseletiva em ratos do grupo controle com acúmulo plasmático do enantiômero (-)-3S,5R, com AUC0-? (2,97 vs 0,99 ?g.h.mL-1), volume de distribuição (9,80 vs 44,60 L.kg-1) e clearance aparente (0,85 vs 2,52 L.h-1.kg-1). A disposição cinética da fluvastatina nos animais do grupo metanol 262 mg/m3, à semelhança do grupo controle foi enantiosseletiva com observação de acúmulo plasmático do enantiômero (-)-3S,5R. Não foram observadas diferenças nas razões enantioméricas entre os animais do grupo controle e metanol 262 mg/m3. As diferenças para o eutômero (+)-3R,5S entre os grupos controle e metanol (1048 mg/m3) foram respectivamente: Cl/F 2.52 (1.64- 3.40) vs 1.51 (1.01-2.06) L.h-1.Kg-1; Vd/F 44.60 (19.20-55.49) vs 10.45 (7.20-15.96) L.Kg-1; t1/2? 10.85 (5.92-14,47) vs 5.23 (4.22-6.27) h; ? 0.06 (0.04-0.11) 0.13 (0.10- 0.16)h-1, AUC 0-? 991.79 (689.57-1491.00) vs 1647.20 (1155.30-2391.60) ng.h.mL-1,e AUC(-)/AUC(+) 2.50 (2.03-4.06) vs 1.22 (0.96-1.56). Em resumo, os dados evidenciam que a exposição ao metanol (1048 mg/m3) resulta em perda da enantiosseletividade com inibição do metabolismo somente do eutômero (+)-3R,5S, alterando portanto de maneira enantiosseletiva a disposição cinética da FV administrada a ratos. / Dislipidemia is one of the main causes of cardiovascular illness and very frequent in the adults population. Fluvastatin, a racemic mixture of the (-)-3S,5R and (+)-3R,5S enantiomers, has been shown to be a potent competitive inhibitor of HMGCoA reductase used in the hypercholesterolemia treatment and with elimination in the man essentially dependent of the CYP2C9. Methanol is used by solvent and is an inhibitor of the CYP2C9 in human beings. The present study reports the influence of methanol inhalation on the enantiosselective pharmacokinetics of fluvastatin in rats. Fluvastatin was administrated by oral gavage (5 mg/Kg) to the animals (n=6/time) and blood samples were collected until 30 hours. The enantiomers were analysed by HPLC using Chiralcel® OD-H column and fluorescence detection. The pharmacokinetics parameters were analysed by Wilcoxon and Mann-Witney tests. The results are reported as mean (95% CI). Kinetic disposition of FV for animals exposed to methanol (262mg/m3), as for control group, was enantiosselective with plasma accumulation of (-)-3S,5R enantiomer. The following differences (p< 0.05) were observed between the control and methanol (1048 mg/m3), apparent total clearance (Cl/F) of 2.52 (1.64-3.40) vs 1.51 (1.01-2.06) L.h-1.Kg-1; apparent volume of distribution (Vd/F) of 44.60 (19.20-55.49) vs 10.45 (7.20-15.96) L.Kg-1; elimination half life (t1/2?) of 10.85 (5.92-14,47) vs 5.23 (4.22-6.27) h; elimination rate constant (?) of 0.06 (0.04-0.11) 0.13 (0.10-0.16) h-1, area under the plasma concentration versus time curve (AUC 0-?) of 991.79 (689.57-1491.00) vs 1647.20 (1155.30- 2391.60) ng.h.mL-1, and AUC(-)/AUC(+) 2.50 (2.03-4.06) vs 1.22 (0.96-1.56). The data demonstrated that methanol inhalation at 1048 mg/m3 results in loss of enantioselectivity with plasmatic accumulation of (+)-3R5S, modifying the enantioselective kinetic disposition of Fluvastatin in rats.