RESUMEN
Piperacillin (PIPC) has been used as one of the most useful beta-lactam antibiotics over the past 10 years. The metabolism of PIPC has been thoroughly investigated and it has been recognized that PIPC gives few metabolites in laboratory species or humans. Recently, an active metabolite, desethyl-piperacillin (DEt-PIPC), was detected in human plasma and urine after PIPC administration. In the current study, human tissues were obtained from organ donors (n = 3) and subcellular fractions (S9) were prepared. The time course of metabolism by S9 mix from liver, kidney cortex, and kidney medulla was then determined using 0.5 mM PIPC. For comparative purposes, rat liver S9 were also prepared and incubated with PIPC under the same conditions. DEt-PIPC was formed by human liver S9 mix from all three specimens studied, with the rate varying approximately eightfold. No DEt-PIPC was detected in any of the incubations with rat liver S9 mix (n = 3) and kidney S9 mix (n = 3) prepared from either the cortex or medulla. In summary, these data suggest that the formation of the unique human metabolite, DEt-PIPC, can be predicted by in vitro studies with human tissues and that this metabolite is formed predominantly by the liver.
Asunto(s)
Hígado/metabolismo , Penicilinas/metabolismo , Piperacilina/análogos & derivados , Piperacilina/metabolismo , Adulto , Animales , Cromatografía Líquida de Alta Presión , Femenino , Humanos , Técnicas In Vitro , Corteza Renal/metabolismo , Corteza Renal/ultraestructura , Médula Renal/metabolismo , Médula Renal/ultraestructura , Hígado/ultraestructura , Masculino , Persona de Mediana Edad , Penicilinas/farmacocinética , Piperacilina/farmacocinética , Ratas , Estándares de Referencia , Especificidad de la EspecieRESUMEN
Desethyl-piperacillin (desethyl-PIPC) is an active metabolite of PIPC which was newly found in clinical field. We carried out a single intravenous toxicity study at the dosage of 2000 mg/kg, and 28-days intravenous toxi-city study at the daily dosage of 400 mg/kg followed by 28-days recovery study using both sexes of rats. The following results were obtained. In the single dose toxicity study, no deaths occurred in rats injected 2000 mg/kg of desethyl-PIPC, therefore it is presumed that minimal lethal dose of desethyl-PIPC is over 2000 mg/kg in both sexes. As clinical signs, decrease in locomotor activity, deep breath and loose stool were observed. In the patho-logical study, dilatation of cecal lumen was observed macroscopically, but no significant changes were observed histologically. In the repeated dose toxicity study, loose stool, increase in water consumption, dilatation of cecal lumen and increase in its weight were noted. These abnormal findings were considered to be due to antimicrobial activity of desethyl-PIPC. In addition, decrease in the ratio of serum gamma-globulin and increase in the ratio of alpha 1-globulin were observed, but A/G ratio was not affected. After withdrawal of desethyl-PIPC administration, these abnormal findings tended to disappear. As mentioned above, the minimal lethal dose of desethyl-PIPC is over 2000 mg/kg in the single dose toxicity study and abnormal signs were slight in the repeated dose toxicity study at the dosage of 400 mg/kg of desethyl-PIPC for 28 days in rats. It is, therefore, concluded that desethyl-PIPC is a low toxic metabolite of PIPC.
Asunto(s)
Piperacilina/análogos & derivados , alfa-Globulinas/metabolismo , Animales , Ciego/efectos de los fármacos , Ciego/patología , Diarrea/inducido químicamente , Dilatación Patológica/inducido químicamente , Ingestión de Líquidos/efectos de los fármacos , Femenino , Inyecciones Intravenosas , Masculino , Actividad Motora/efectos de los fármacos , Tamaño de los Órganos/efectos de los fármacos , Piperacilina/administración & dosificación , Piperacilina/toxicidad , Ratas , Ratas Sprague-Dawley , Respiración/efectos de los fármacos , gammaglobulinas/metabolismoRESUMEN
The relationship between the chemical structure and mode of action of piperacillin-analogues (PIPC-analogues) against Pseudomonas aeruginosa was investigated. The antibacterial activities of PIPC-analogues became stronger as the chain length of the alkyl group on the N-4 position in 2,3-dioxopiperazine when tested in constitutively beta-lactamase-producing strain, but not paralleled in wild and beta-lactamase-less strains. The outer membrane permeability was hardly affected by the chain length of the alkyl group at the N-4 position. The stability to beta-lactamase was stronger with the increase of the number of the carbon atoms of N-4 position. In the binding-affinities to the lethal penicillin-binding proteins (PBPs), compounds PIPC (C-2), C-3 and C-4 showed lower ID50 values than compounds C-1, C-6 and C-8. These results suggested that the stability to beta-lactamase was the governing part for the antibacterial activity in constitutively beta-lactamase-producing strain, and the binding affinity to lethal PBPs directly contributed to the antibacterial activity in wild and beta-lactamase-less strains.
Asunto(s)
Proteínas Bacterianas , Hexosiltransferasas , Peptidil Transferasas , Piperacilina/análogos & derivados , Pseudomonas aeruginosa/efectos de los fármacos , Proteínas de la Membrana Bacteriana Externa/análisis , Proteínas Portadoras/metabolismo , Permeabilidad de la Membrana Celular , Electroforesis en Gel de Poliacrilamida , Estructura Molecular , Muramoilpentapéptido Carboxipeptidasa/metabolismo , Proteínas de Unión a las Penicilinas , Piperacilina/metabolismo , Piperacilina/farmacología , Pseudomonas aeruginosa/enzimología , beta-Lactamasas/biosíntesisRESUMEN
The relationship between the chemical structure and the mode of action of piperacillin-analogues (PIPC-analogues) against Escherichia coli and Klebsiella pneumoniae were investigated. The antibacterial activity of PIPC-analogues increased with an increase in the number of carbon atoms at the N-4 position of 2,3-dioxopiperazine. Their mode of action is discussed on the basis of the results of studies on outer membrane permeability, stability to beta-lactamase and binding affinity to penicillin-binding proteins (PBPs). The outer membrane permeability and stability to beta-lactamase were hardly affected by the chain length of the alkyl group at the N-4 position. On the other hand, the affinity to PBPs, especially to PBP 3, became stronger with increase of the number of carbon atoms at N-4 position. These results suggest that increased affinity to PBPs is the main reason for the increased antibacterial activity of the PIPC-analogues reported here.
Asunto(s)
Proteínas Bacterianas , Proteínas Portadoras/metabolismo , Permeabilidad de la Membrana Celular , Hexosiltransferasas , Muramoilpentapéptido Carboxipeptidasa/metabolismo , Peptidil Transferasas , Piperacilina/análogos & derivados , beta-Lactamasas/metabolismo , Unión Competitiva , Fenómenos Químicos , Química , Escherichia coli/efectos de los fármacos , Klebsiella pneumoniae/efectos de los fármacos , Penicilina G/metabolismo , Proteínas de Unión a las Penicilinas , Piperacilina/metabolismo , Piperacilina/farmacología , Relación Estructura-ActividadRESUMEN
Piperacillin amide (IV) was successfully identified as the predominant impurity in commercial lots of piperacillin monohydrate (III). The impurity was isolated via a preparative liquid chromatographic scheme utilizing Florisil as the adsorbent and a mobile phase of water-acetonitrile (4:96, v/v). The isolated component had nearly the same reverse-phase HPLC properties as piperacillin and was chemically and thermally unstable. This labile impurity was spectroscopically identified by field desorption (FD), fast atom bombardment (FAB) with collision activation decomposition (CAD), and desorption chemical ionization (DCI) mass spectrometries , and NMR and IR spectrometries . Identity was confirmed on comparison of the chromatographic and spectrometric data of the impurity with an independently synthesized sample of piperacillin amide.