RESUMEN
The role of the mitochondrial Na/Ca-exchanger (mNCX) in hearts exposed to ischemia-reperfusion (I/R) and pretreated with cardioplegia (CPG) was studied from a mechano-calorimetric approach. No-flow ischemia (ISCH) and reperfusion (REP) were developed in isolated rat hearts pretreated with 10 micromol/L clonazepam (CLZP), an inhibitor of the mNCX, and (or) a high K+ - low Ca2+ solution (CPG). Left ventricular end diastolic pressure (LVEDP), pressure development during beats (P), and the steady heat release (Ht) were continuously measured and muscle contents of ATP and PCr were analyzed at the end of REP. During REP, Ht increased more than P, reducing muscle economy (P/Ht) and the ATP content. CPG induced an increase in P recovery during REP (to 90% +/- 10% of preISCH) with respect to nonpretreated hearts (control, C, to 64% +/- 10%, p < 0.05). In contrast, CLZP reduced P recovery of CPG-hearts (50% +/- 6.4%, p < 0.05) and increased LVEDP in C hearts. To evaluate effects on sarcoplasmic reticulum (SR) function, ischemic hearts were reperfused with 10 mmol/L caffeine -36 mmol/L Na (C - caff - low Na). It increased LVEDP, which afterwards slowly relaxed, whereas Ht increased (by about 6.5 mW/g). CLZP sped up the relaxation with higher DeltaHt, C - caff - low Na produced higher contracture and lower Ht in perfused than in ischemic hearts. Values of DeltaHt were compared with reported fluxes of Ca2+-transporters, suggesting that mitochondria may be in part responsible for the DeltaHt during C - caff - low Na REP. Results suggest that ISCH-REP reduced the SR store for the recovery of contractility, but induced Ca2+ movement from the mitochondria to the SR stores. Also, mitochondria and SR are able to remove cytosolic Ca2+ during overloads (as under caffeine), through the mNCX and the uniporter. CPG increases Ca2+ cycling from mitochondria to the SR, which contributes to the higher recovery of P. In contrast, CLZP produces a deleterious effect on ISCH-REP associated with higher heat release and reduced resynthesis of high energy phosphates, which suggests the induction of mitochondrial Ca cycling and uncoupling.
Asunto(s)
Clonazepam/farmacología , Mitocondrias/fisiología , Daño por Reperfusión Miocárdica/fisiopatología , Potasio/farmacología , Adenosina Trifosfato/metabolismo , Animales , Anticonvulsivantes/farmacología , Cafeína/farmacología , Calcio/metabolismo , Soluciones Cardiopléjicas/farmacología , Cromatografía Líquida de Alta Presión , Diástole/efectos de los fármacos , Diástole/fisiología , Metabolismo Energético/efectos de los fármacos , Femenino , Corazón/efectos de los fármacos , Corazón/fisiopatología , Paro Cardíaco Inducido/métodos , Masculino , Contracción Miocárdica/efectos de los fármacos , Daño por Reperfusión Miocárdica/metabolismo , Miocardio/metabolismo , Fosfocreatina/metabolismo , Ratas , Ratas Sprague-Dawley , Retículo Sarcoplasmático/efectos de los fármacos , Retículo Sarcoplasmático/metabolismo , Función Ventricular Izquierda/efectos de los fármacos , Función Ventricular Izquierda/fisiologíaRESUMEN
AIM: Na/Ca-exchanger (NCX) and sarcoplasmic reticulum (SR) roles during the protection by a cardioplegic solution (25 mm K and 0.5 mm Ca, CPG) against ischaemia-reperfusion was studied. METHODS: Contractile performance (CP) and high energy phosphates contents (HEP) were evaluated in isolated ventricles from rats. They were pre-treated with Krebs (C) or CPG and submitted to no-flow ischaemia and reperfusion (I-R). KB-R7943 5 microm (inhibitor of NCX in reverse mode), 8 mm caffeine and ionic changes were used pre-ischaemically to evaluate each pathway role. RESULTS: During R, CP recovered to 77 +/- 8% of basal in CPG-hearts vs. 55 +/- 8% (P < 0.05) in C-ones. CPG avoided the increases in end diastolic pressure (LVEDP) and in PCr/ATP ratio during I-R. Low [Na]o (78 mm) under both, CPG-2 mm Ca and C, increased further the LVEDP during I-R. LVEDP was also transiently increased by caffeine-CPG, but not modified by KB-R7943. The recovery of CP during reperfusion of CPG-hearts was decreased either, by caffeine (to approximately 75%), low [Na]o-2 mm Ca-CPG (to approximately 40%) and KB-R7943 (to approximately 16%). CONCLUSIONS: CPG protected hearts from ischaemic contracture by attenuating the fall in ATP and removing diastolic Ca by means of NCX in forward mode. Moreover, CPG induces higher CP recovery during reperfusion by participation of SR and NCX in reverse mode. This work remarks the use of CPG based on the functional role of these Ca handling-mechanisms in a pathophysiological condition as ischaemia-reperfusion.
Asunto(s)
Isquemia Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/prevención & control , Retículo Sarcoplasmático/metabolismo , Intercambiador de Sodio-Calcio/metabolismo , Tiourea/análogos & derivados , Adenosina Trifosfato/análisis , Animales , Antiarrítmicos/farmacología , Presión Sanguínea/fisiología , Cafeína/farmacología , Calcio/metabolismo , Soluciones Cardiopléjicas/farmacología , Estimulantes del Sistema Nervioso Central/farmacología , Femenino , Masculino , Contracción Miocárdica/efectos de los fármacos , Contracción Miocárdica/fisiología , Fosfocreatina/análisis , Ratas , Ratas Wistar , Sodio/metabolismo , Tiourea/farmacología , Función Ventricular Izquierda/fisiologíaRESUMEN
The determination of adenine nucleotides and creatine compounds has great importance in the characterization of ischemic myocardial injury and post-ischemic recovery. It was developed by an HPLC method for the quantification of creatine (Cr), creatine phosphate (CrP), hypoxanthine (HX), AMP, adenosine (Ad), ADP and ATP in isolated perfused rat hearts. The chromatographic conditions were: RP 18 column; mobile phase composed by KH(2)PO(4) (215 mM), tetrabutylammonium hydrogen sulfate (2.3mM), acetonitrile (4%) and KOH (1M 0.4%); flow rate 1 ml min(-1); temperature 25 degrees C; injection volume 20 microl; detection at 220 nm and height peak (HP) as the integration parameter. The method was validated by means of linearity and sensitivity evaluations, using calibration curves done with five concentration levels of each compound. The limits of quantification (LOQ) were also determined. The system precision was calculated as the coefficient of variation for five injections for each compound tested. The purity of the peaks was established using enzymatic peak shift analysis with hexokinase and creatine kinase and also comparing HP at various wavelengths. Frozen hearts were homogenized with a mechanical homogenizer for 3 min at 0 degrees C added with 5 ml of 0.4N HCLO(4). After precipitation with 0.8 ml of 2M KOH the extract was shaked for 2 min and later centrifuged at 0 degrees C for 10 min. The supernatant was kept on ice, filtrated and injected into the HPLC system. The results show that the method for the determination of Cr, CrP, HX, AMP, Ad, ADP and ATP by HPLC here described has good linearity, LOQ, precision, specificity and is simple and rapid to perform.
Asunto(s)
Miocardio/química , Miocardio/metabolismo , Tecnología Farmacéutica/métodos , Nucleótidos de Adenina/análisis , Animales , Cromatografía Líquida de Alta Presión/métodos , Creatina/análisis , Ratas , Ratas WistarRESUMEN
High Performance Liquid Chromatographic (HPLC) method was applied in this study to comparatively evaluate the stability of tablets in their original package which 150 mg of Ranitidine from six different pharmaceutical laboratories in the market, according to ICH conditions for accelerated testing: 40 degrees C, 75% RH with and without light for six months. The stability at environmental conditions was evaluated for a twelve-month period, with and without light, with the same purpose. Ranitidine is widely used to treat peptic ulcer diseases. Ranitidine is susceptible to degradation under the influence of light, humidity and temperature. The chromatographic conditions were: RP-18 column of 250 mm yen 4 mm ID and a particle size of 5 mm; mobile phase of Acetonitrile-Ammonium acetate solution (0.2 M) (70:30; v/v) (pH*6) adjusted with glacial acetic acid; flow rate of 1 ml min-1; 25 degrees C of temperature; detection at 322 nm; injection volume of 20 ml, using height peak as the integration parameter. The results obtained at six months indicate that the stability of Ranitidine depends on the correct formulation and the primary container. The remaining content of Ranitidine, dissolved percentage in vitro and total impurity percentage were determined by HPLC. Organoleptic characteristics were visually examined. The proposed analytical method was validated and linearity, precision and selectivity were determined. Degradation products were detected.
Asunto(s)
Ranitidina/análisis , Cromatografía Líquida de Alta Presión , Estabilidad de Medicamentos , Ambiente , Reproducibilidad de los Resultados , Solubilidad , ComprimidosRESUMEN
This study was conducted to compare the bioavailability of two prolonged-release pharmaceutical forms containing 300 mg of diltiazem. The test formulation is a new design of tablets with a hydrophilic matrix, and the reference formulation is capsules containing prolonged liberation microgranules, in the same dose, that are commercially available in the pharmaceutical market. Diltiazem plasma concentrations were analyzed by high-performance liquid chromatography (HPLC), which involves solid-phase extraction for plasma sample preparation. Twelve healthy volunteers participated in the study, which had a single-dose, two-treatment, two-sequence-crossover, randomized design. The preparations were compared using pharmacokinetic parameters such as the area under the plasma concentration-time curve AUC(0-36), peak plasma concentration Cmax, and Cmax/AUC(0-36) ratio as a measure for the absorption rate. No statistically significant difference was observed for any of the parameters, and the 90% confidence intervals calculated for the ratio of the logarithmically transformed AUC(0-36) and Cmax/AUC(0-36) values of both formulations were within the bioequivalence limit of 0.80-1.25. Moreover, an in vitro study of dissolution according to USP 23 was conducted, and the in vitro parameters were calculated.
Asunto(s)
Bloqueadores de los Canales de Calcio/farmacocinética , Diltiazem/farmacocinética , Administración Oral , Adulto , Disponibilidad Biológica , Bloqueadores de los Canales de Calcio/sangre , Cápsulas , Cromatografía Líquida de Alta Presión , Estudios Cruzados , Diltiazem/sangre , Femenino , Humanos , Masculino , Persona de Mediana Edad , Solubilidad , Comprimidos RecubiertosRESUMEN
The aim of the present study was to comparatively evaluate the stability of capsules containing 20 mg of Omeprazole, in enteric coated pellets, from seven pharmaceutical laboratories on Argentine market. The stability test was performed under the conditions indicated by the ICH: 40 degrees C, 75% HR, with and without light, during a six month period. The remaining content of Omeprazole, total percentage of impurities and percentage of released active principle in vitro, were determined by HPLC. The organoleptic characteristics of the pellets were visually examined. The results obtained at six months indicate that, from the seven products studied, four were found to have a content of Omeprazole higher than 90% of the labeled amount, in both lighting conditions tested, and also comply with the USP23 specifications with respect to the release in vitro. We conclude that the progressive darkening of the pellets indicates, qualitatively, the level of degradation of the product and that the stability of Omeprazole depends on the correct formulation and the primary container.
Asunto(s)
Antiulcerosos/administración & dosificación , Omeprazol/administración & dosificación , Antiulcerosos/análisis , Cápsulas , Cromatografía Líquida de Alta Presión , Estabilidad de Medicamentos , Omeprazol/análisis , Solubilidad , Comprimidos RecubiertosRESUMEN
The aim of this work was to develop an analytical method for a simultaneous determination of cyanocobalamin (Vitamin B12), betamethasone, and diclofenac, present in pharmaceutical formulations, by high performance liquid chromatography, assuring rapidity, accuracy, precision, and selectivity. The working conditions were as follows: RP18 column of 125 mm x 4 mm ID and a particle size of 5 microm; mobile phase acetonitrile-water (40:60; v/v) (pH* 3.45) adjusted with acetic acidl flow gradient from 0.8 to 1.9 ml/min.; injection volume of 20 microl; temperature 34 degrees C and detection at 240 nm. The method was adequately validated, and linearity, accuracy, as well as the system, method and interday precision, for each active principle, were determined.
Asunto(s)
Betametasona/análisis , Diclofenaco/análisis , Vitamina B 12/análisis , Ácido Acético/química , Acetonitrilos/química , Betametasona/química , Calibración , Química Farmacéutica , Cromatografía Líquida de Alta Presión/métodos , Diclofenaco/química , Estudios de Evaluación como Asunto , Vigilancia de Productos Comercializados , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Solubilidad , Vitamina B 12/químicaAsunto(s)
Antagonistas de Dopamina/química , Antagonistas de Dopamina/orina , Metoclopramida/química , Metoclopramida/orina , Adulto , Disponibilidad Biológica , Cromatografía Líquida de Alta Presión , Estudios Cruzados , Antagonistas de Dopamina/farmacocinética , Método Doble Ciego , Femenino , Humanos , Masculino , Metoclopramida/farmacocinética , Solubilidad , ComprimidosRESUMEN
A bioavailability study of two lots of paracetamol tablets was carried out in 5 healthy volunteers, using a crossover aleatory design, and drug monitoring in urine and saliva by high performance liquid chromatography (HPLC). Results were correlated with those obtained in an in vitro dissolution study. Statistical evaluation of bioavailability parameters indicates that the two formulations may be considered bioequivalent, in spite of differences found during early stages of the absorption process, which were preventable according to an in vitro dissolution study.
Asunto(s)
Acetaminofén/farmacocinética , Analgésicos no Narcóticos/farmacocinética , Saliva/química , Acetaminofén/análisis , Acetaminofén/orina , Adulto , Analgésicos no Narcóticos/química , Analgésicos no Narcóticos/orina , Disponibilidad Biológica , Femenino , Humanos , Comprimidos , Equivalencia TerapéuticaRESUMEN
The effect of the manufacturing technology on the dissolution of ampicillin tablets have been analyzed. Several kinetic parameters were then calculated. The dissolution rate of ampicillin increases in tablets prepared by direct compression or dry granulation, with microcrystalline cellulose and colloidal silicon dioxide. Studies of in vitro bioequivalence of the pharmaceutical products available in the Argentine market were performed. We concluded that not all commercial products are equivalent.