Journal of pharmacobio-dynamics最新文献

The apparent in vitro kinetic constants of uridine diphosphate-glucuronyltransferase (UDP-GT) activities towards E6080, 1-naphthol (1-N) and 4-hydroxybiphenyl (4-HB) were determined using microsomes, to assess the effect of inducing agents and evaluate species and tissue differences. In rats, the 3-methylcholanthrene and beta-naphthoflavone treatments increased the Vmax app/KM app values for E6080, 13- and 8-fold, and those for 1-N, 1.9- and 1.7-fold, respectively, but did not affect those for 4-HB. Phenobarbital was ineffective on the UDP-GT activity toward E6080. In rats and rhesus monkeys, the intestinal mucosa had higher specific UDP-GT activity toward E6080 than did the liver, and the rank order of the Vmax app/KM app value for E6080 in the intestinal mucosa was rhesus monkey > rat > guinea pig > beagle. In guinea pig, the Vmax app/KM app value for E6080 in the liver was 4 times higher than that in the intestinal mucosa. Both the Vmax app/KM app values for 1-N and 4-HB in the liver of all species studied were higher than those in the intestinal mucosa, and guinea pig liver showed the highest values, while, about the Vmax app for 1-N and 4-HB, beagle liver had the highest values. In the beagle intestinal mucosa, the Vmax app/KM app values for all 3 substrates studied were extremely low.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of metabolically 3H-labeled (1-->3)-beta-D-glucan (3H-SSG) obtained from the culture filtrate of Sclerotinia sclerotiorum IFO 9395, in various tissues after intraperitoneal administration into ICR mice (250 micrograms/mouse) was examined. 3H-SSG was mainly detected in liver, spleen, and blood, and a negligible amount was excreted into the feces and excrement within 2 d. The significant amount of 3H-SSG remained in liver and spleen after 1 month. On the other hand, SSG was not incorporated effectively in vivo and in vitro by peritoneal exudate macrophages (0.5 microgram/1 x 10(6) M phi) Similarly in vivo, the majority of 3H-SSG distributed in spleen and liver were recovered from the non-cellular fraction and not from splenic macrophage and Kupffer cell fractions. These results suggested that (1-->3)-beta-D-glucans would not be easily incorporated by the host cells to degrade and exclude from the body even after the onset of the biological response modifier activity.

The effects of cisapride on the gastrointestinal contractile activity and pharmacokinetics of disopyramide were determined in beagle dogs and patients with arrhythmia. In the animal experiments, the gastric motor index was significantly decreased by i.v. administration of disopyramide in a dose-dependent fashion. The peak decrease of the motor index was observed within 5 min after i.v. injection of disopyramide; the motor index then recovered gradually to the level present prior to drug administration. I.v. administration of cisapride (0.5 mg/kg) markedly increased gastrointestinal contractile activity following the decrease induced by disopyramide pretreatment (5 mg/kg, i.v.). In the clinical studies, the gastric emptying test was performed using the acetaminophen method. A significant correlation between plasma concentrations of disopyramide and gastric emptying time has been found (p < 0.001). The combination of disopyramide (100 mg t.i.d.) and cisapride (2.5 mg t.i.d.) significantly increased gastric emptying compared with that induced by disopyramide alone. The peak plasma concentration of disopyramide in association with cisapride oral administration was significantly higher, and the apparent absorption rate constant and lag time of disopyramide were about 2-fold higher and 2-fold shorter, respectively, than for disopyramide alone. Cisapride, acting as a cholinergic agonist, may counteract the anticholinergic effect of disopyramide on gastric motility. As a factor influencing drug absorption, gastric emptying is of importance, as it determines the rate of drug delivery to the small intestine. Therefore, the oral administration of disopyramide with cisapride may be useful for patients with delayed gastric emptying.

The development of tolerance induced by daily repeated administration of 10 mg/kg of s.c. morphine was suppressed by combined injection of adrenergic blockers, 10 mg/kg i.p. phentolamine or propranolol, in mice. However, this treatment could not prevent the development of physical dependence as evidenced by the naloxone precipitated abstinence signs. Thus, we provide a new evidence that morphine analgesia, tolerance and physical dependence is dissociable from each other.

The percutaneous (p.c.) absorption of pindolol, a beta-blocker, through rabbit skin was examined by in vitro and in vivo studies. Additionally, for practical use of the transdermal system (TTS), a trial for sustaining a suitable plasma concentration of pindolol by using a rate-controlling membrane and for describing plasma drug levels after p.c. application by using a simple pharmacokinetic model was tested. As a result, the drug penetrated through rabbit skin in vitro at a zero-order rate. In vivo, the drug was also absorbed through the skin from a gel base with or without enhancers. The gel preparation with Azone (Rp. 2) gave high plasma levels of pindolol. The transdermal system produced with Rp. 2 and a rate-controlling membrane (Hipore 4050) provided relatively constant plasma levels for 48 h. The model presented could describe the time course of plasma pindolol concentrations following p.c. application of the systems.

The relationship between physicochemical properties and oral absorption was investigated in prodrugs for the oral delivery of disodium cromoglycate (DSCG). To improve the lipophilicity of DSCG, various lipophilic moieties were introduced into the twin carboxyl groups. However, this did not lead to improved oral absorption in rabbits because of loss of water solubility, in spite of improved lipophilicity. Water-soluble prodrugs, in which an amino acid was introduced into a hydroxy group by ester linkage in addition to ethyl residues at twin carboxyl groups of DSCG, were synthesized and examined for oral absorption in rabbits and rats. The oral absorption of these prodrugs was affected by the species of amino acids introduced as a water-soluble moiety. Therefore, we examined the relation between the oral absorption of water-soluble prodrugs and the hydrolysis rate of the amino acid moiety. A good linear correlation was obtained between the oral absorption and the hydrolysis rate constant catalyzed by digestive enzymes, trypsin or alpha-chymotrypsin. It was thus concluded that the amino acid moiety of water-soluble prodrugs must be rapidly hydrolyzed to a permeable lipophilic prodrug still possessing the ethyl moiety at twin carboxyl groups in the small intestinal tract for good oral absorption.

Ca(2+)-Induced membrane damage of energized mitochondria has been proposed to be due to lipid peroxidation induced by Ca2+. To examine this possibility, we studied the effects of the radical scavenger, 3,5-di-tert-butyl-4-hydroxytoluene (BHT), and its derivative, 3,5-di-tert-butyl-4-methoxytoluene (MeO-BHT), on membrane damage of respiring mitochondria induced by Ca2+ in the presence of inorganic phosphate. Both compounds inhibited Ca(2+)-induced damage almost completely at 20 microM, and their effects were identical, although MeO-BHT had no radical scavenging ability. These results indicate that the protective effects of BHT and MeO-BHT are not due to their radical scavenging ability. Thus, free radicals are concluded not to be involved in Ca(2+)-induced membrane damage of mitochondria.

A competitive radioimmunoassay (RIA) and a sandwich enzyme-linked immunosorbent assay (ELISA) for the measurement of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in rat serum was developed using polyclonal antibody obtained by immunizing rabbits with rhG-CSF. The anti-rhG-CSF antibody did not recognize other colony-stimulating factors or interleukins. RIA and ELISA gave satisfactory reproducibility as judged by intra- and inter-assay precision. Good agreements between the RIA, ELISA and bioassay were observed with rat serum samples after administration of rhG-CSF. The competitive RIA and sandwich ELISA described here appear to be as equally useful as the bioassay in studying the pharmacokinetics of rhG-CSF in animals.

Human erythrocytes treated with diamide (0.2 mM) or N-ethylmaleimide (0.1 mM) at 37 degrees C for 1 h were susceptible to binding of anti-band 3 immunoglobulin G autoantibody and hemoglobin. A definite degree of cell modification appeared to be required for the effective bindings since the cells treated with the reagents above these concentrations were less susceptible. The enhanced binding activities of the cells treated with diamide were abolished on treatment with dithiothreitol. Partial blocking of SH groups of the membrane proteins but not disulfide-mediated protein cross-linking may be essential for the formation of band 3 senescent antigen, which may not be a neo-antigen formed by chemical modification of band 3 but an antigen formed by topological alterations of the molecules in the membrane.