RESUMEN
The intravenous injection of cimetidine in a dose of 20 mg/kg enhanced verografine and iodamide excretion in chronic canine experiments. The higher verografine and iodamide excretion was due to their increased renal tubular secretion. In dogs, cimetidine unchanged the secretion of cardiotrast, a test agent for anionic transport. Possible extrarenal mechanisms of action of cimetidine on verografine and iodamide transport were also examined.
Asunto(s)
Cimetidina/farmacología , Diatrizoato de Meglumina/metabolismo , Iodamida/metabolismo , Riñón/efectos de los fármacos , Animales , Cimetidina/administración & dosificación , Diatrizoato de Meglumina/análisis , Diuresis/efectos de los fármacos , Perros , Interacciones Farmacológicas , Tasa de Filtración Glomerular/efectos de los fármacos , Iodamida/análisis , Yodopiraceto/análisis , Yodopiraceto/metabolismo , Riñón/metabolismo , Factores de TiempoRESUMEN
Ten patients with normal serum creatinine and no evidence of acute cholecystitis were found to have vicarious excretion of water-soluble contrast media into the gallbladder 20 minutes to 72 hours after injection. Eight of the ten had unilateral renal pathology. Two patients, however, had bilaterally normal kidneys. The patients had been injected with either diatrizoate, iothalamate, or iodamide. The mechanisms and pathophysiology of vicarious contrast excretion are discussed. The vicarious excretion of intravascular contrast in the gallbladder does not in itself indicate renal or hepatobiliary disease. Although commonly associated with unilateral renal pathology, vicarious gallbladder excretion of urographic contrast may be a normal variant in some patients.
Asunto(s)
Medios de Contraste/metabolismo , Creatinina/sangre , Vesícula Biliar/metabolismo , Adolescente , Adulto , Niño , Diatrizoato/metabolismo , Femenino , Humanos , Iodamida/metabolismo , Ácido Yotalámico/metabolismo , Riñón/metabolismo , Masculino , Persona de Mediana EdadRESUMEN
The excretory behavior of nine nephrotropic contrast agents with varying physicochemical properties such as charge, lipophilicity, and molecular size was investigated. Renal clearance in comparison with inulin was determined by means of the continuous infusion method. Each contrast agent was infused at three dose levels in four to six rabbits. The investigations show that tubular transportation in proportion to glomerular filtration decreases with increasing dosages of all the contrast agents. Thus, with the highest concentration in plasma all contrast agents are eliminated at more or less the glomerular filtration rate (GFR). After administration of the low dosages the following differences are found: 1) Net tubular secretion increases for the monomeric contrast agent acids with increasing lipophilicity, in the order diatrizoate congruent to iothalamate less than iodamide less than acetrizoate. 2) The clearance studies do not reveal any tubular secretion or reabsorption for a hydrophilic cationic contrast agent. 3) The nonionic contrast agents do not show net secretion. The more lipophilic they are, the more they are reabsorbed. 4) Two dimeric contrast agents also do not reveal any tubular secretion. They seem to be reabsorbed more than monomers with the same charge.
Asunto(s)
Medios de Contraste , Yohexol/análogos & derivados , Riñón/fisiología , Ácido Acetrizoico/metabolismo , Animales , Diatrizoato de Meglumina/metabolismo , Tasa de Filtración Glomerular , Inulina , Iodamida/metabolismo , Yotalamato de Meglumina/metabolismo , Ácido Yoxáglico , Túbulos Renales/fisiología , Metrizamida/metabolismo , Conejos , Ácidos Triyodobenzoicos/metabolismoRESUMEN
The pharmacokinetic characteristics of iodamide, a contrast agent for excretion urography, were studied in seven normal subjects and in 15 patients with various degrees of renal impairment. Two different formulations were administered, namely, a 65% solution (iodamide 300) by slow intravenous injection and a 24% solution by slow intravenous (drip) infusion. Both preparations of iodamide exhibited characteristics of an open two-compartment model. In both normal subjects and patients, the contrast agent was excreted almost exlusively in urine. In normal subjects, the pharmacokinetic parameters of both formulations were similar, with a distribution half-life (1/2alpha) of about 3 minutes and a disposition half-life (t1/2beta) of about 69 minutes. An average of 84 per cent of the dose was excreted in urine within 4 hours after administration of iodamide with net renal tubular secretion of about 38 per cent. The binding of iodamide to plasma proteins was negligible, and the extent of biotransformation of iodamide was minimal. In patients with renal impairment, the disposition half-life (t1/2beta) of iodamide ranged from 4.1 to 16.4 hours. Other changes in pharmacokinetic parameters were also seen in patients with renal impairment.
Asunto(s)
Iodamida/metabolismo , Yodobenzoatos/metabolismo , Enfermedades Renales/metabolismo , Ensayos Clínicos como Asunto , Femenino , Semivida , Humanos , Infusiones Parenterales , Inyecciones Intravenosas , Iodamida/sangre , Iodamida/orina , Cinética , MasculinoRESUMEN
Active tubular secretion of iodamide, a water-soluble contrast medium, was demonstrated by comparing the clearances of iodamide, iothalamate and inulin. Passive tubular back diffusion was not found. The fraction excreted by tubular secretion was significantly reduced at "clinical" plasma concentrations. The glomerular filtration rate was slightly depressed at these concentrations of iodamide and diatrizoate.
Asunto(s)
Diatrizoato/metabolismo , Iodamida/metabolismo , Yodobenzoatos/metabolismo , Túbulos Renales/metabolismo , Adolescente , Adulto , Anciano , Proteínas Sanguíneas/metabolismo , Relación Dosis-Respuesta a Droga , Femenino , Tasa de Filtración Glomerular , Humanos , Insulina/metabolismo , Ácido Yotalámico/metabolismo , Masculino , Tasa de Depuración Metabólica , Persona de Mediana Edad , Unión ProteicaRESUMEN
The pharmaco-kinetics of angiographic contrast media in the extra-vascular space, which are largely unknown, were investigated experimentally in dogs. As part of a basic study, using radio-active contrast media, it was possible to determine the concentration and rate of elimination in practically all organs and tissues. Measurements were carried out first after prolonged infusion of the contrast under conditions of balanced flow, and secondly six hours after the end of the infusion. It was therefore possible to determine the inflow and loss of contrast medium in various organs, or organs systems. The most commonly used angiographic contrast media in Germany were investigated. Their kinetic behaviour is largely identical, their pattern of distribution and elimination depended principally on the organ or tissue. A comprehensive discussion of the results of all the experiments will be given in the third article.