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The use of inhibitors of gastric acid secretion (IGAS), especially proton pump inhibitors (PPI), has been associated with increased cardiovascular risk. While the mechanisms involved are not known, there is evidence supporting increased oxidative stress, a major activator of matrix metalloproteinases (MMP), as an important player in such effect. However, there is no study showing whether other IGAS such as histamine H2-receptor blockers (H2RB) cause similar effects. This study aimed at examining whether treatment with the H2RB ranitidine promotes oxidative stress resulting in vascular MMP activation and corresponding functional and structural alterations in the vasculature, as compared with those found with the PPI omeprazole. Male Wistar rats were treated (4 weeks) with vehicle (2% tween 20), omeprazole (10 mg/Kg/day; i.p.) or ranitidine (100 mg/Kg/day; gavage). Then the aorta was collected to perform functional, biochemical, and morphometric analysis. Both ranitidine and omeprazole increased gastric pH and oxidative stress assessed in situ with the fluorescent dye dihydroethidium (DHE) and with lucigenin chemiluminescence assay. Both IGAS augmented vascular activated MMP-2. These findings were associated with aortic remodeling (increased media/lumen ratio and number of cells/µm2). Both IGAS also impaired the endothelium-dependent relaxation induced by acetylcholine (isolated aortic ring preparation). This study provides evidence that the H2RB ranitidine induces vascular dysfunction, redox alterations, and remodeling similar to those found with the PPI omeprazole. These findings strongly suggest that IGAS increase oxidative stress and matrix metalloproteinase-2 activity leading to vascular remodeling, which helps to explain the increased cardiovascular risk associated with the use of those drugs.
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Introducción: Los medicamentos antiulcerosos son utilizados frecuentemente en pacientes hospitalizados, sin embargo, a menudo este uso no está indicado. Objetivo: Describir la frecuencia de prescripción e indicación de medicamentos para prevenir el sangrado gastrointestinal en pacientes hospitalizados. Materiales y métodos: Estudio de corte trasversal, descriptivo, prospectivo del servicio de Medicina Interna de la Sociedad de Cirugía de Bogotá- Hospital de San José de Bogotá, Colombia. Se excluyeron pacientes con diagnóstico de sangrado gastrointestinal o antecedente de alergia a los medicamentos antiulcerosos. Se recolectaron datos demográficos, así como fármacos prescritos. Se determinó si la indicación del fármaco era adecuada y se identificó el tipo de error de prescripción. Resultados: Se incluyeron 179 pacientes, 102 (57%) mujeres. Promedio de edad de 61,3 años (±20,2). El principal diagnóstico de ingreso fue enfermedad infecciosa 76 (42,4%). Del total de pacientes, 165 (92,17%) recibieron medicamento para prevención del sangrado gastrointestinal. La indicación fue adecuada en 75 pacientes (41,89%). El error más frecuente fue el uso en pacientes de bajo riesgo de sangrado, 101 (97,1%). Conclusión: Un alto porcentaje de los pacientes recibió medicación para la prevención del sangrado gastrointestinal. En aproximadamente la mitad de estos no estaba indicada.
Introduction: Anti-ulcer medications are frequently used in hospitalized patients, yet their use is not usually indicated. Objective: To describe the frequency of prescription and indication of medications to prevent gastrointestinal bleeding in hospitalized patients. Materials and methods: A cross-sectional, descriptive, prospective study was carried out in the Internal Medicine service of the Surgery Society of Bogota-San Jose Hospital of Bogota (Colombia). Excluded patients were those with either a gastrointestinal bleeding diagnosis or a history of allergy to anti-ulcer medications. Demographic data and information regarding prescribed medications were collected. It was determined whether the medicine indication was adequate and the type of prescription error was identified. Results: 179 patients were included in the study, 57% (102) of which were women. The average age was 61.3 (±20.2) years old. Infectious disease was the main admission diagnosis (76; 42.4%). A 92.17% (165) of the total number of patients received medications to prevent gastrointestinal bleeding. This indication was adequate for 75 (41.89%) patients. The most frequent error was their use in bleeding low-risk patients (101; 97.1%). Conclusion: A high percentage of patients received medication to prevent gastrointestinal bleeding. However, in about half of these patients it was not indicated.
Assuntos
Humanos , Preparações Farmacêuticas , Saúde Pública , Doença , Ranitidina , Omeprazol , Guia , Prevenção de Doenças , Hemorragia GastrointestinalRESUMO
The purpose of the study was to develop a novel, directly compressible, co-processed excipient capable of providing a controlled-release drug system for the pharmaceutical industry. A co-processed powder was formed by adsorption of solid lipid nanoparticles (SLN) as a controlled-release film onto a functional excipient, in this case, dicalcium phosphate dihydrate (DPD), for direct compression (Di-Tab®). The co-processed excipient has advantages: easy to implement; solvent-free; industrial scaling-up; good rheological and compressibility properties; and the capability to form an inert platform. Six different batches of Di-Tab®:SLN weight ratios were prepared (4:0.6, 3:0.6, 2:0.6, 1:0.6, 0.5:0.6, and 0.25:0.6). BCS class III ranitidine hydrochloride was selected as a drug model to evaluate the mixture's controlled-release capabilities. The co-processed excipients were characterized in terms of powder rheology and dissolution rate. The best Di-Tab®:SLN ratio proved to be 2:0.6, as it showed high functionality with good flow and compressibility properties (Carr Index = 16 ± 1, Hausner Index = 1.19 ± 0.04). This ratio could control release for up to 8 h, so it fits the ideal profile calculated based on biopharmaceutical data. The compressed systems obtained using this powder mixture behave as a matrix platform in which Fickian diffusion governs the release. The Higuchi model can explain their behavior.
Assuntos
Preparações de Ação Retardada/farmacologia , Excipientes/química , Lipídeos/química , Nanopartículas/química , Força Compressiva , Liberação Controlada de Fármacos , Nanopartículas/ultraestrutura , Tamanho da Partícula , Pós , Ranitidina/farmacologia , ReologiaRESUMO
Since the biopharmaceutical quality of generic drug formulations depends on the quality of the reference products and also information about the in-vitro release performance of drugs under different conditions is scarce in the literature, a dissolution study of four reference tablets was performed. Each drug was representative of one Class of the Biopharmaceutical Classification System. The in-vitro release performance of propranolol-HCl, carbamazepine, ranitidine-HCl, and metronidazole was evaluated using a USP basket and paddle apparatus at different agitation rates (50, 75, and 100 rpm) with two doses of each drug. In all experiments, pharmacopeial dissolution media was used and the samples were taken with automatic equipment at specific times up to 60 min, except for propranolol-HCl, for which the samples were taken up to 30 min. The dissolution profiles were compared by model-independent, model-dependent, and ANOVA-based comparisons. The three methods of data comparison showed that low vs. high doses were significantly different (P < 0.05), which may influence cases in which biowaivers of propranolol-HCl and ranitidine-HCl are requested. Additionally, the results showed that despite different hydrodynamic environments produced by the basket and paddle apparatus, under certain conditions, both types of equipment generated comparable in-vitro results. Variables such as the dose, agitation rate, and type of dissolution apparatus are important factors to consider in designing dissolution tests for drug products. This information can be used to test a new dosage when there is no pharmacopeial method available to perform a dissolution study. Further researches on the in-vitro release performance of reference drug products are required.
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Proton pump inhibitors (PPI) are suppressors of gastric acid secretion (SGAS) that decrease gastric nitric oxide (NO) formation from nitrite and increase the cardiovascular risk. However, H2 receptor antagonists (H2RA) are considered safer than PPIs. We challenged this notion and hypothesized that both omeprazole (PPI) and ranitidine (H2RA) attenuate the responses to oral nitrite because both drugs increase gastric pH and therefore could decrease nitrite-derived NO formation in the stomach. We examined the blood pressure responses to oral nitrite in hypertensive rats treated with omeprazole, ranitidine, or vehicle. Chemiluminensce-based assays were used to measure gastric NO formation, plasma and gastric concentrations of nitrite, nitrate, and nitrosylated species (RXNO) to clarify the mechanism involved in the effects of SGAS on the responses to oral nitrite. Both drugs increased gastric pH, impaired oral nitrite-induced hypotensive responses, gastric NO formation, and blunted the increases in circulating RXNO concentrations, but not in circulating nitrite and nitrate concentrations. These findings were reproduced in a second study using sodium acetate buffers at pH 3.5, 4.5, and 5.5 to mimic gastric pH found with vehicle, ranitidine, and omeprazole, respectively. Increasing gastric pH impaired oral nitrite-induced hypotensive responses, gastric NO formation, and blunted the increases in circulating RXNO concentrations, but not in circulating nitrite and nitrate concentrations. Our results clearly indicate that SGAS impair nitrite-induced gastric formation of NO and vasoactive RXNO in a pH-dependent manner, thus resulting in impaired responses to oral nitrite. These findings may have several clinical implications, particularly to patients with cardiovascular diseases.
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Anti-Hipertensivos/administração & dosagem , Ácido Gástrico/química , Ácido Gástrico/metabolismo , Antagonistas dos Receptores H2 da Histamina/administração & dosagem , Hipertensão/tratamento farmacológico , Omeprazol/administração & dosagem , Inibidores da Bomba de Prótons/administração & dosagem , Ranitidina/administração & dosagem , Nitrito de Sódio/administração & dosagem , Administração Oral , Animais , Pressão Sanguínea/efeitos dos fármacos , Modelos Animais de Doenças , Mucosa Gástrica/metabolismo , Concentração de Íons de Hidrogênio/efeitos dos fármacos , Masculino , Nitratos/análise , Nitratos/sangue , Óxido Nítrico/análise , Óxido Nítrico/metabolismo , Nitritos/análise , Nitritos/sangue , Ratos , Ratos Wistar , Resultado do TratamentoRESUMO
Histamine [2-(4-Imidazolyl)-ethylamine] modulates different biological processes, through histamine H1 and H2 receptors, and their respective blockers are widely used in treating allergic and gastric acid-related disorders. Histamine H1 and H2 receptor crossdesensitization and cointernalization induced by its agonists have been previously described. In this study, we show how this crosstalk determines the response to histamine H1 and H2 receptor inverse agonists and how histamine H1 and H2 receptor inverse agonists interfere with the other receptor's response to agonists. By desensitization assays we demonstrate that histamine H1 and H2 receptor inverse agonists induce a crossregulation between both receptors. In this sense, the histamine H1 receptor inverse agonists desensitize the cAMP response to amthamine, a histamine H2 receptor agonist. In turn, histamine H2 receptor inverse agonists interfere with histamine H1 receptor signaling. We also determine that the crossdesensitization induced by histamine H1 or H2 receptor agonists alters the histamine inverse agonists receptor response: activation of histamine H1 receptor affects cAMP response induced by histamine H2 receptor inverse agonists, whereas histamine H2 receptor agonist induces a negative regulation on the anti-inflammatory response of histamine H1 receptor inverse agonists. Binding studies revealed that histamine H1 and H2 receptors cointernalize after stimulus with histamine receptor inverse agonists. In addition, the inhibition of the internalization process prevents receptor crossregulation. Our study provides new insights in the mechanisms of action of histamine H1 and H2 receptors that explain the effect of histamine H1 and H2 receptor inverse agonists and opens up new venues for novel therapeutic applications.
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Agonistas dos Receptores Histamínicos/metabolismo , Antagonistas dos Receptores Histamínicos H1/metabolismo , Receptores Histamínicos H1/metabolismo , Receptores Histamínicos H2/metabolismo , Linhagem Celular , Linhagem Celular Tumoral , Células HEK293 , Histamina/metabolismo , Humanos , Transdução de Sinais/fisiologia , Células U937RESUMO
Despite the pivotal role GPCRs play in cellular signaling, it is only in the recent years that structural biology has begun to elucidate how GPCRs function and to provide a platform for structure-based drug design. It is postulated that GPCR activation involves the movement of transmembrane helices. The finding that many residues, which have been shown to be critical for receptor activation and are highly conserved among different GPCRs, are clustered in particular positions of transmembrane helices suggests that activation of GPCRs may involve common molecular mechanisms. In particular, phenylalanine 6.44, located in the upper half of TMVI, is highly conserved among almost all GPCRs. We generated Phe 2436.44 Ala/Ser mutants of histamine H2 receptor and found that while the substitutions do not affect receptor expression or ligand signaling, are able to specifically alter cimetidine and ranitidine mechanisms of action from simply inactivating the receptor to produce a ligand-induced G-protein sequestering conformation, that interferes with the signaling of ß2-adrenoceptor. Taking advantage of the cubic ternary complex model, and mathematically modeling our results, we hypothesize that this alteration in ligand mechanism of action is consequence of a change in ligand-induced conformational rearrangement of receptor and its effect on G-protein coupling. Our results show that receptor point mutations can not only alter receptor behavior, as shown for activating/inactivating mutations, but also can have more subtle effects changing ligand mechanism of action.
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Cimetidina/farmacologia , Antagonistas dos Receptores H2 da Histamina/farmacologia , Ranitidina/farmacologia , Receptores Histamínicos H2/genética , Células HEK293 , Humanos , Modelos Moleculares , Mutação , Conformação ProteicaRESUMO
BACKGROUND: The inhibition of gastric acid secretion with ranitidine is frequently prescribed off-label to newborns admitted to neonatal intensive care units (NICU). Some studies show that the use of inhibitors of gastric acid secretion (IGAS) may predispose to infections and necrotising enterocolitis (NEC), but there are few data to confirm this association. This study aimed to compare the rates of neonatal infections and NEC among preterm infants (<37 weeks gestation) hospitalised in a NICU exposed or not to treatment with ranitidine. METHODS: A retrospective cohort study was conducted with all consecutive preterm newborns admitted to a NICU between August-2014 and October-2015. The rates of infection, NEC, and death of newborns exposed or not to ranitidine were recorded. RESULTS: A total of 300 newborns were enrolled, of which 115 had received ranitidine and 185 had not. The two groups were similar with regard to the main demographic and clinical characteristics. Forty-eight (41.7%) of the 115 infants exposed to ranitidine and 49 (26.5%) of the 185 infants not exposed were infected (RR = 1.6, 95%CI 1.1-2.2, p = 0.006). The late onset (>48 h) blood culture positive infection rate was higher in the group exposed to ranitidine than in the untreated group (13.0% vs. 3.8%, p = 0.001). There was no significant association between the use of ranitidine and NEC (Bell stage >II) (p = 0.36). The mortality rate risk was 4-fold higher in infants receiving ranitidine (16.5% vs. 8.6%, p < 0.001). CONCLUSION: Ranitidine use in neonates was associated with an increased risk of infections and mortality, but not with NEC.
Assuntos
Infecção Hospitalar/epidemiologia , Enterocolite Necrosante/epidemiologia , Ranitidina/efeitos adversos , Adulto , Brasil/epidemiologia , Estudos de Coortes , Infecção Hospitalar/induzido quimicamente , Infecção Hospitalar/etiologia , Enterocolite Necrosante/induzido quimicamente , Enterocolite Necrosante/etiologia , Feminino , Idade Gestacional , Mortalidade Hospitalar , Humanos , Lactente , Recém-Nascido , Recém-Nascido Prematuro , Unidades de Terapia Intensiva Neonatal/estatística & dados numéricos , Masculino , Ranitidina/administração & dosagem , Ranitidina/uso terapêutico , Estudos RetrospectivosRESUMO
BACKGROUND: The aim of this study was to determine the effect of gestational age on pharmacokinetics of ranitidine in newborns with gastroesophageal reflux. METHODS: A prospective, descriptive and pharmacokinetic study was carried out in 30 pre-term and 20 full-term babies. 3 mg/kg of ranitidine was administered intravenously to all the babies and at 0.25, 0.5, 1, 2, 4, and 8 h following the administration, samples of blood were drawn to assess ranitidine levels using high performance liquid chromatographic technique. RESULTS: Pharmacokinetics of ranitidine had a bi-exponential behavior with a half-life elimination of (t1/2el) 2.79 h, area under curve (AUC) of 1688 ng/mL, volume of distribution (Vd) of 1.44 L/kg, and clearance (Cl) of 5.9 L/kg/h. The median plasmatic concentration in pre-terms was 1113 ng/mL and 280 ng/mL in full-terms. Vd, t1/2 and Cl presented high values in preterm although the correlation of Cl with glomerular filtration in term newborns was better. CONCLUSIONS: Plasma levels of ranitidine depend on the gestational age of the newborns. However, the possible relationship between after-birth age and pharmacokinetics of the neonates as their internal organs get matured without minding their gestational background.
Assuntos
Antiulcerosos/farmacocinética , Refluxo Gastroesofágico/tratamento farmacológico , Doenças do Prematuro/tratamento farmacológico , Ranitidina/farmacocinética , Antiulcerosos/sangue , Antiulcerosos/uso terapêutico , Área Sob a Curva , Cromatografia Líquida de Alta Pressão , Feminino , Refluxo Gastroesofágico/sangue , Idade Gestacional , Meia-Vida , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Doenças do Prematuro/sangue , Injeções Intravenosas , Masculino , Estudos Prospectivos , Ranitidina/sangue , Ranitidina/uso terapêuticoRESUMO
ABSTRACT Background Nonsteroidal anti-inflammatory drugs induces gastric mucosal lesions because of its acidic properties. Ranitidine, an H2 receptor antagonist, has proved beneficial in patients with gastric ulcers. Objective The present study was performed to assess the effect of administering ranitidine in Nonsteroidal anti-inflammatory drugs (diclofenac, nimesulide) induced gastropathy, and their effect on the histopathology of stomach, kidney and liver. Methods Diclofenac, nimesulide, and ranitidine were administered in doses of 2, 4, and 6 mg/kg, p.o. once daily for 14 days, and their effect on gastric volume, acidity, mean ulcer number, and gastric pH. In addition, histopathological examination was also performed on sections of stomach, kidney and liver. Results Following the administration of diclofenac or nimesulide, all the gastric parameters were significantly altered as well as the histopathology of stomach, liver and kidney. In the control group, the renal sections showed normal glomeruli with no thickening of glomerular basement membrane, while in diclofenac alone, nimesulide alone, and ranitidine with nimesulide groups, the thickening of glomerular basement membrane was observed. These alterations were observed to be reversed in the ranitidine with diclofenac group. In the sections from the liver, the control group showed anastomosing plates and cords of cuboidal hepatocytes with round well stained nuclei and abundant cytoplasm. In the ranitidine with diclofenac, and ranitidine with nimesulide groups, mild dilatation of sinusoids is seen coupled with prominence of central vein. In the diclofenac alone and nimesulide alone groups, the proximal and distal convoluted tubules show mild focal tubular necrosis. In the gastric sections, the control group showed several folds forming villi, and the epithelial lining surface of the mucosa. In the ranitidine with diclofenac, and ranitidine with nimesulide groups, the duodenum showed scattered inflammatory cells composed predominantly of lymphocytes. In diclofenac alone and nimesulide alone group, the sections from the gastric areas showed partial necrosis and mild chronic inflammation respectively. Conclusion The study, therefore, has provided therapeutic rationale towards simultaneous administration of H2 receptor blocker ranitidine with diclofenac to be more beneficial as compared to ranitidine with nimesulide, to minimise the gastric intolerance of diclofenac in long term treatment of inflammatory conditions.
RESUMO Contexto Anti-inflamatórios não esteroidais induzem lesões da mucosa gástrica devido às suas propriedades ácidas. Ranitidina, um antagonista dos receptores H2, revelou-se benéfico em pacientes com úlceras gástricas. Objetivo - O presente estudo foi realizado para avaliar o efeito da administração de ranitidina em gastropatia induzida por anti-inflamatórios não esteroidais (diclofenaco, nimesulida) e seu efeito sobre a histopatologia do estômago, dos rins e fígado. Métodos Diclofenaco, nimesulida e ranitidina foram administradas em doses de 2, 4 e 6 mg/kg, p.o. uma vez diariamente por 14 dias e seu efeito sobre o volume gástrico, acidez, significam o número de úlcera e o pH gástrico. Além disso, o exame histopatológico também foi realizado em seções do estômago, dos rins e fígado. Resultados Após a administração de diclofenaco ou nimesulida, todos os parâmetros gástricos foram significativamente alterados assim como a histopatologia do estômago, fígado e rim. No grupo controle, as seções renais mostraram glomérulos normais sem espessamento da membrana basal glomerular, enquanto em diclofenaco isolado, nimesulida isolado e grupos com ranitidina e nimesulida, foi observado espessamento da membrana basal glomerular. Estas alterações observou-se serem revertidas no grupo ranitidina com diclofenaco. As seções do fígado, o grupo controle mostrou placas e cordões de hepatócitos cuboidais anastomosados com núcleos bem demarcados e citoplasma abundante. Nos grupos ranitidina com diclofenaco e ranitidina com nimesulida, leve dilatação dos sinusoides é vista acoplados com proeminência de veia central. Nos grupos diclofenaco e nimesulida sozinhos, túbulos proximais e distais contorcidos mostram necrose tubular focal leve. Nas secções gástricas, o grupo controle mostrou várias dobras formando vilosidades e a superfície do revestimento epitelial da mucosa. Nos grupos ranitidina com diclofenaco e ranitidina com nimesulida, o duodeno mostrou dispersas células inflamatórias predominantemente compostas por linfócitos. Nos grupos diclofenaco e nimesulida sozinhos, as secções de áreas gástricas mostraram necrose parcial e inflamação crônica moderada respectivamente. Conclusão - O estudo, portanto, forneceu o fundamento terapêutico para administração simultânea de bloqueador de receptor H2 (ranitidina) com diclofenaco, sendo mais benéfica em comparação com ranitidina com nimesulida para minimizar a intolerância gástrica de diclofenaco no tratamento a longo prazo de condições inflamatórias.