Ranitidine treatment inducing methemoglobinemia in male Wistar rats

A idiossincrasia a fármacos é um evento adverso de origem desconhecida, que acontece em poucas pessoas. É conhecido que a ranitidina, um antagonista de receptores H2, causa reações idiossincrásicas. Para investigar uma possível indução da ranitidina em relação a hemotoxicidade, o fármaco foi administrado intraperitonealmente (i.p.) em dois de seis grupos de ratos machos Wistar (n=6), pesando entre 200-220 g. O grupo I recebeu 200µL de solução salina (NaCl) por via intraperitoneal ( i.p.), o grupo II recebeu 200µL de NaCl durante quatro dias consecutivos, o grupo III (controle do veículo,) recebeu 200 µL de dimetilsulfóxido (DMSO) em dose única, o grupo IV (controle do veículo) recebeu 200 µL de DMSO, durante quatro dias consecutivos, o grupo V recebeu 100 mg/kg de ranitidina em 200 µL de DMSO em dose única, o grupo VI recebeu 50 mg/kg de ranitidina em 200 µL de DMSO durante quatro dias consecutivos. Realizou-se eritrograma, leucograma e determinação da porcentagem de metemoglobina por espectrofotometria. A porcentagem de metemoglobinemia aumentou de forma significativa em ambos os grupos tratados. A contagem de neutrófilos mostrou uma discreta redução nos regimes de tratamento, ocasionada provavelmente pela mobilização marginal dos mesmos. No regime de doses múltiplas, observou-se aumento no número de leucócitos, mas seu perfil de manutenção de distribuição permaneceu o mesmo. A ranitidina induziu a formação de metemoglobinemia nas doses administradas, sugerindo que a partir de uma certa concentração e ou esquema de dosagem, o fármaco pode ser um indutor do processo.Drug idiosyncrasy is an adverse event of unknown etiology that occurs in a small fraction of people taking a drug. The histamine-2 (H2)-receptor antagonist ranitidine causes idiosyncratic reactions in patients. To investigate the hypothesis that ranitidine could induce hematological toxic effects, the drug was administered intraperitoneally (ip) to two of six groups of 200-220 g male Wistar rats (n=6). Group I received as single dose of saline solution (NaCl, 200 µL) Group II received 200 µL of NaCl, ip, at 0, 24, 48 and 72 h, Group III (controls of the vehicle) received as single dose of dimethyl sulfoxide (DMSO, 200µL), ip, Group IV (controls of the vehicle) received 200 µL of DMSO, ip, at 0, 24, 48, and 72 h, Group V received a single dose of 100 mg/kg of ranitidine in 200 µL of DMSO) ip, Group VI received 50 mg/kg of ranitidine, in 200 µL of DMSO, ip, at 0, 24, 48, and 72 h. Erythrograms, leucograms were measured; percent methemoglobin content of the blood was analyzed spectophotometrically. Methemoglobinemia increased to a significant extent following ranitidine treatment, in both study groups. White blood cell and neutrophil counts showed a discrete reduction following either regime of treatment. A marginal mobilization of the neutrophil pool probably occured. Following the multiple dose regime, leukocyte counts increased, but their distribution maintenance profile remained the same. The administration of ranitidine to rats induces methemoglobinemia in the administered doses, suggesting that from a certain concentration and dosage scheme the substance can be methemeglobinemia inductor

L-arginine, a nitric oxide precursor, reduces dapsone-induced methemoglobinemia in rats

Dapsone use is frequently associated to hematological side effects such as methemoglobinemia and hemolytic anemia, which are related to N-hydroxylation mediated by the P450 enzyme system. The aim of the present study was to evaluate the influence of L-arginine supplementation, a precursor for the synthesis of nitric oxide, as single or multiple dose regimens on dapsone-induced methemoglobinemia. Male Wistar rats were treated with L-arginine at 5, 15, 30, 60 and 180 mg/kg doses (p.o., gavage) in single or multiple dose regimens 2 hours prior to dapsone administration (40 mg/kg, i.p.). The effect of the nitric oxide synthase inhibitor L-NAME was investigated by treatment with multiple doses of 30 mg/kg (p.o., gavage) 2 hours before dapsone administration. Blood samples were collected 2 hours after dapsone administration. Erythrocytic methemoglobin levels were assayed by spectrophotometry. The results showed that multiple dose supplementations with 5 and 15 mg/kg L-arginine reduced dapsone-induced methemoglobin levels. This effect is mediated by nitric oxide formation, since the reduction in methemoglobin levels by L-arginine is blocked by simultaneous administration with L-NAME, a nitric oxide synthase inhibitor.O uso da dapsona é frequentemente associado a efeitos adversos hematológicos, como a metemoglobinemia \ud e anemia hemolítica, ambos relacionados com a N-hidroxilação mediada pelo sistema P450. O objetivo \ud do estudo foi avaliar a influência da suplementação de L-arginina, um precursor da síntese de óxido \ud nítrico, administrado em regime de dose única ou múltipla na metemoglobinemia induzida pela dapsona. \ud Ratos machos Wistar foram tratados com L-arginina (po, gavagem) em dose única ou múltipla de 5, 15, \ud 30, 60 e 180 mg/kg 2 horas antes da administração de dapsona (40 mg/kg, ip). O efeito do L-NAME, \ud um inibidor de óxido nítrico sintase (NOS), foi avaliado através do tratamento com doses múltiplas de \ud 30 mg/kg. Amostras de sangue foram coletadas duas horas após a administração de dapsona. A \ud concentração de metemoglobina eritrocitária foi analisada por espectrofotometria. Os resultados \ud mostraram que a suplementação em dose múltipla de 5 e 15 mg/kg de L-arginina reduziu os níveis de \ud metemoglobina induzida pela dapsona. Este efeito é mediado pela formação de óxido nítrico, uma vez \ud que a redução nos níveis de metemoglobina pela L-arginina é bloqueada pela administração simultânea \ud de L-NAME, um inibidor da óxido nítrico sintase.CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)FURPFUR

L-arginine, a nitric oxide precursor, reduces dapsone-induced methemoglobinemia in rats

O uso da dapsona é frequentemente associado a efeitos adversos hematológicos, como a metemoglobinemia e anemia hemolítica, ambos relacionados com a N-hidroxilação mediada pelo sistema P450. O objetivo do estudo foi avaliar a influência da suplementação de L-arginina, um precursor da síntese de óxido nítrico, administrado em regime de dose única ou múltipla na metemoglobinemia induzida pela dapsona. Ratos machos Wistar foram tratados com L-arginina (po, gavagem) em dose única ou múltipla de 5, 15, 30, 60 e 180 mg/kg 2 horas antes da administração de dapsona (40 mg/kg, ip). O efeito do L-NAME, um inibidor de óxido nítrico sintase (NOS), foi avaliado através do tratamento com doses múltiplas de 30 mg/kg. Amostras de sangue foram coletadas duas horas após a administração de dapsona. A concentração de metemoglobina eritrocitária foi analisada por espectrofotometria. Os resultados mostraram que a suplementação em dose múltipla de 5 e 15 mg/kg de L-arginina reduziu os níveis de metemoglobina induzida pela dapsona. Este efeito é mediado pela formação de óxido nítrico, uma vez que a redução nos níveis de metemoglobina pela L-arginina é bloqueada pela administração simultânea de L-NAME, um inibidor da óxido nítrico sintase.Dapsone use is frequently associated to hematological side effects such as methemoglobinemia and hemolytic anemia, which are related to N-hydroxylation mediated by the P450 enzyme system. The aim of the present study was to evaluate the influence of L-arginine supplementation, a precursor for the synthesis of nitric oxide, as single or multiple dose regimens on dapsone-induced methemoglobinemia. Male Wistar rats were treated with L-arginine at 5, 15, 30, 60 and 180 mg/kg doses (p.o., gavage) in single or multiple dose regimens 2 hours prior to dapsone administration (40 mg/kg, i.p.). The effect of the nitric oxide synthase inhibitor L-NAME was investigated by treatment with multiple doses of 30 mg/kg (p.o., gavage) 2 hours before dapsone administration. Blood samples were collected 2 hours after dapsone administration. Erythrocytic methemoglobin levels were assayed by spectrophotometry. The results showed that multiple dose supplementations with 5 and 15 mg/kg L-arginine reduced dapsone-induced methemoglobin levels. This effect is mediated by nitric oxide formation, since the reduction in methemoglobin levels by L-arginine is blocked by simultaneous administration with L-NAME, a nitric oxide synthase inhibitor

Determination of levetiracetam in human plasma by dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry

Levetiracetam (LEV) is an antiepileptic drug that is clinically effective in generalized and partial epilepsy syndromes. The use of this drug has been increasing in clinical practice and intra- or -interindividual variability has been exhibited for special population. For this reason, bioanalytical methods are required for drug monitoring in biological matrices. So this work presents a dispersive liquid-liquid microextraction method followed by gas chromatography-mass spectrometry (DLLME-GC-MS) for LEV quantification in human plasma. However, due to the matrix complexity a previous purification step is required. Unlike other pretreatment techniques presented in the literature, for the first time, a procedure employing ultrafiltration tubes Amicon (R) (10 kDa porous size) without organic solvent consumption was developed. GC-MS analyses were carried out using a linear temperature program, capillary fused silica column, and helium as the carrier gas. DLLME optimized parameters were type and volume of extraction and dispersing solvents, salt addition, and vortex agitation time. Under chosen parameters (extraction solvent: chloroform, 130 mu Ldispersing solvent: isopropyl alcohol, 400 mu Lno salt addition and no vortex agitation time), the method was completely validated and all parameters were in agreement with the literature recommendations. LEV was quantified in patient's plasma sample using less than 550 mu L of organic solvent.Sao Paulo Research Foundation (FAPESP) [2012/07210-8]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Department of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, 14040-903 Ribeirão Preto, SP, BrazilDepartment of Exact and Earth Sciences, Institute of Environmental, Chemical and Pharmaceutical Sciences, Federal University of São Paulo, 09972-270 Diadema, SP, BrazilDepartament of Chemistry, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, 14040-901 Ribeirão Preto, SP, BrazilDepartment of Clinical Analysis, Toxicology and Food Science, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, 14040-903 Ribeirão Preto, SP, BrazilDepartment of Exact and Earth Sciences, Institute of Environmental, Chemical and Pharmaceutical Sciences, Federal University of São Paulo, 09972-270 Diadema, SP, BrazilFAPESP: 2012/07210-8Web of Scienc

METODOLOGIA ANALÍTICA DE RESÍDUO DO HERBICIDA 2,4-D (ÁCIDO 2,4-DICLOROFENOXIACÉTICO) EM AMOSTRAS DE ÁGUA EM ÁREA DE CULTIVO DE CANA-DE-AÇÚCAR

Desenvolveu-se método de análise de resíduo do herbicida 2,4-D para amostras de água coletadas na microbacia do Córrego do Espraiado no período de 1996 a 1999. A avaliação da tendência do produto alcançar camadas mais profundas do solo foi efetuada por simulação de sistemas (CMLS-94-Chemical Movement in Layered Soils) para melhor entendimento do comportamento do herbicida. O método analítico, utilizando cromatografia a gás, permitiu correlação de 99,9% entre a área dos picos e a concentração existente, indicando alta eficiência. Não foi encontrado resíduo de 2,4-D na água coletada nos anos de 1996 a 1999, o que também reforça os dados encontrados por simulação. Esses indicaram que 60 cm foi a profundidade máxima atingida no período de três anos, tanto para o Latossolo Roxo quanto para o Latossolo Vermelho Escuro. O mesmo estudo evidenciou que a partir do segundo ano após a aplicação já não havia mais resíduos do produto em ambos os solos estudados. ANALYTICAL METHODOLOGY OF 2,4-D (2,4-DICHLOROPHENOXYACETIC ACID) HERBICIDE RESIDUES IN SAMPLES OF WATER IN A SUGAR-CANE CULTIVATION AREA IN BRAZIL Abstract A method of analysis of the herbicide 2,4-D was developed for water samples collected in the Espraiado watershed in the period of 1996 and 1999. The evaluation of the tendency of the product to reach deeper layers of the soil was made by systems simulation (CMLS-94-Chemical Movement in Layered Soils) for better understanding of the herbicide behavior. The gas chromatography analytical method resulted in a 99.9% correlation of the peaks area in the graphics and the herbicide concentration, and indicated that it was highly effective. No residue of 2,4-D was detected in water in the years of 1996 to 1999, which also reinforce the data obtained by simulation. This indicated the leaching down to 60 cm., reached in a three-year period, in both types of soils, Latossolo Roxo and Latossolo Vermelho-Escuro The same study evidenced that from the second year after application there were no more product residues in both types of the soils studied

Influence of the clinical profile of patients with refractory epilepsy on lamotrigine plasma concentration

The purpose of this work was to evaluate the influence of the clinical profile on lamotrigine (LTG) plasma concentrations from patients with refractory epileptic seizures. In this cross-sectional study, therapeutic monitoring of LTG, and questionnaires with 75 patients with refractory epileptic seizures of a Hospital in Ribeirão Preto-SP-Brazil were performed. The multiple linear regression model was used to verify association between the LTG plasma concentrations and the independent variables. Covariance analysis was used to compare the mean LTG plasma concentration among the co-medication groups. The LTG plasma concentration was associated both with the LTG dosage (mg/kg/day) (p=0.0096) and with the use of first generation antiepileptic drugs (AED) (p<0.01), being carbamazepine (CBZ) and phenytoin (PHT), the AEDs showing the most prominent influence in reducing LTG plasma concentrations. Adverse events, adherence to the pharmacological treatment, and epileptic seizures frequency, did not show significant correlation with LTG plasma concentration values. The conclusion is that LTG plasma concentration is significantly influenced by the LTG dosage and by the concomitant use of a first generation AED

Stir bar-sorptive extraction, solid phase extraction and liquid-liquid extraction for levetiracetam determination in human plasma: comparing recovery rates

Levetiracetam (LEV), an antiepileptic drug (AED) with favorable pharmacokinetic profile, is increasingly being used in clinical practice, although information on its metabolism and disposition are still being generated. Therefore a simple, robust and fast liquid-liquid extraction (LLE) followed by high-performance liquid chromatography method is described that could be used for both pharmacokinetic and therapeutic drug monitoring (TDM) purposes. Moreover, recovery rates of LEV in plasma were compared among LLE, stir bar-sorptive extraction (SBSE), and solid-phase extraction (SPE). Solvent extraction with dichloromethane yielded a plasma residue free from usual interferences such as commonly co-prescribed AEDs, and recoveries around 90% (LLE), 60% (SPE) and 10% (SBSE). Separation was obtained using reverse phase Select B column with ultraviolet detection (235 nm). Mobile phase consisted of methanol:sodium acetate buffer 0.125 M pH 4.4 (20:80, v/v). The method was linear over a range of 2.8-220.0 µg mL-1. The intra- and inter-assay precision and accuracy were studied at three concentrations; relative standard deviation was less than 10%. The limit of quantification was 2.8 µg mL-1. This robust method was successfully applied to analyze plasma samples from patients with epilepsy and therefore might be used for pharmacokinetic and TDM purposes.</p

Potentiation of dapsone induced methemoglobinemia by N-acetylcysteine in rats

Dapsona (DDS) (4,4'diaminodifenilsulfona), fármaco de escolha para o tratamento da hanseníase, freqüentemente induz anemia hemolítica e metemoglobinemia. A N-hidroxilação, uma de suas principais vias de biotransformação, é constantemente relacionada com a metemoglobinemia observada com o uso do fármaco. Com o objetivo de prevenir a hemotoxicidade induzida pela DDS, N-acetilcisteína, fármaco precursor de glutationa, foi administrada em associação com DDS em ratos machos Wistar pesando 220-240 g. Os animais foram anestesiados e o sangue coletado da aorta para determinação da concentração plasmática de DDS por CLAE, determinação dos níveis de metemoglobina e de glutationa eritrocitária por espectrofotometria, e avaliação de parâmetros bioquímicos e hematológicos. Os resultados obtidos mostraram que a N-acetilcisteína potenciou o efeito metemoglobinizante da dapsona devido ao aumento de sua concentração plasmática e conseqüente aumento da formação da N-hidroxilamina. Concluímos que as interações medicamentosas com a dapsona exigem estudos individualizados a fim de evitar os efeitos adversos do fármaco.Dapsone (DDS) (4,4'diaminodiphenylsulfone), the drug of choice for the treatment of leprosy, frequently induces hemolytic anemia and methemoglobinemia. N-hydroxylation, one of the major pathways of biotransformation, has been constantly related to the methemoglobinemia after the use of the drug. In order to prevent the dapsone-induced hemotoxicity, N-acetylcysteine, a drug precursor of glutathione, was administered in combination with DDS to male Wistar rats, weighting 220-240 g. The animals were then anaesthetized and blood was collected from the aorta for determination of plasma DDS concentration by HPLC, determination of methemoglobinemia and glutathione by spectrophotometry, and for biochemical and hematological parameters. Our results showed that N-acetylcysteine enhanced dapsone-induced methemoglobinemia due to increased dapsone plasmatic concentration and consequent increased N-hydroxylamine formation. We concluded that drug interactions with dapsone require individually studies in order to avoid undesirable effects of dapsone

Anxiolytic-like effect of oxytocin in the simulated public speaking test

Oxytocin (OT) is known to be involved in anxiety, as well as cardiovascular and hormonal regulation. The objective of this study was to assess the acute effect of intranasally administered OT on subjective states, as well as cardiovascular and endocrine parameters, in healthy volunteers (n = 14) performing a simulated public speaking test. OT or placebo was administered intranasally 50 min before the test. Assessments were made across time during the experimental session: (1) baseline (-30 min); (2) pre-test (-15 min); (3) anticipation of the speech (50 min); (4) during the speech (1:03 h), post-test time 1 (1:26 h), and post-test time 2 (1:46 h). Subjective states were evaluated by self-assessment scales. Cortisol serum and plasma adrenocorticotropic hormone (ACTH) were measured. Additionally, heart rate, blood pressure, skin conductance, and the number of spontaneous fluctuations in skin conductance were measured. Compared with placebo, OT reduced the Visual Analogue Mood Scale (VAMS) anxiety index during the pre-test phase only, while increasing sedation at the pre-test, anticipation, and speech phases. OT also lowered the skin conductance level at the pre-test, anticipation, speech, and post-test 2 phases. Other parameters evaluated were not significantly affected by OT. The present results show that OT reduces anticipatory anxiety, but does not affect public speaking fear, suggesting that this hormone has anxiolytic properties.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2002/13197-2]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), BrazilFundacao de Apoio ao Ensino, Pesquisa e Assistencia (FAEPA) do Hospital das Clinicas da FMRPUSPCAPE

Effect of the acidified extract of Moringa oleifera leaves as a supplement in the in vitro culture medium of sheep preantral follicles

This study was conducted to evaluate the effects of the acidified extract of M. oleifera leaves as a supplement into the base medium for in vitro culture of sheep isolated secondary follicles. Follicles were isolated and cultured for 12 days in α-MEM+(supplemented with bovine serum albumin, insulin, glutamine, hypoxanthine, transferrin, selenium, and ascorbic acid) with or without 0.1; 0.2 or 0.4 mg/ml of the acidified extract of M. oleifera. Follicle morphology, antral cavity formation, follicular and oocyte diameter, glutathione (GSH) concentration, mitochondrial activity and meiotic resumption were evaluated. After 12 days of culture, there was no significant difference among treatments in relation to follicular morphology, antral cavity formation, diameter and mitochondrial activity. Nevertheless, oocytes from follicles cultured in α-MEM+ showed greater GSH concentration than media containing M. oleifera extract. Furthermore, the concentration of 0.4 mg/ml M. oleifera extract significantly increased the percentage of fully grown oocyte (≥ 110 µm) when compared to the other treatments. In conclusion, the concentration of 0.4 mg/ml M. oleifera extract as a supplement of the culture medium, maintained the survival, and increased the percentage of fully grown oocytes