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Stereoselective renal secretion of carbenicillin in rabbits: Role of the organic anion transporter at the renal brush border membrane (1998)

Itoh, Tomoo ; Nakaura, Hiromi ; Koyano, Shin-Ichi ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Chirality 10 (1998), S. 349-357

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ISSN: 0899-0042

Keywords: carbenicillin ; stereoselective ; secretion ; transport ; rabbit ; membrane vesicles ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Stereoselectivity in the renal secretion of carbenicillin (CBPC) was studied in rabbits. Significant renal secretion of CBPC was observed in vivo, with the secretion of the S-epimer being greater than that of the R-epimer. Stereoselective transport of CBPC was further studied in vitro using basolateral and brush border membrane vesicles prepared from rabbit kidneys. The transport of CBPC by the organic anion transporter into the basolateral membrane vesicles (BLMV) was not stereoselective. In contrast, a distinct stereoselectivity was observed in the transport of CBPC by the organic anion transporter into the brush border membrane vesicles (BBMV), with the transport of the S-epimer being more favorable. Significant epimer-epimer interactions were also observed in the transport into BBMV. The stereoselectivity of the transport of CBPC was calculated from the kinetic parameters with consideration of epimer-epimer interactions and was similar to that observed in vivo. It was concluded that the observed stereoselectivity in the renal secretion of CBPC in vivo reflected that of transport via the organic anion transporter located at the brush border membrane. Chirality 10:349-357, 1998. © 1998 Wiley-Liss, Inc.

Additional Material: 7 Ill.

Type of Medium: Electronic Resource

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2

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Stereoselectivity and enantiomer-enantiomer interactions in the binding of ibuprofen to human serum albumin (1997)

Itoh, Tomoo ; Saura, Yoshikazu ; Tsuda, Yasuyuki ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Chirality 9 (1997), S. 643-649

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ISSN: 0899-0042

Keywords: ibuprofen ; stereoselective ; binding ; HSA ; interaction ; fluorescent ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Binding of ibuprofen (IB) enantiomers to human serum albumin (HSA) was studied using a chiral fluorescent derivatizing reagent, which enabled the measurement of IB enantiomers at a concentration as low as 5 × 10-8 M. Scatchard analyses revealed that there were two classes of binding sites for both enantiomers. For the high affinity site, the number of the binding sites was one for both enantiomers, and the binding constant of R-IB was 2.3-fold greater than that of S-IB. The difference in the affinity at the high affinity site may result in the stereoselective binding of IB enantiomers at therapeutic concentrations. It was confirmed that the high affinity site of IB enantiomers is Site II (diazepam binding site) by using site marker ligands. Also, significant enantiomer-enantiomer interactions were observed in the binding. The binding data were quantitatively analyzed and a binding model with an assumption of competitive interactions only at the high affinity site simulated the binding characteristics of IB enantiomers fairly well. Chirality 9:643-649, 1997. © 1997 Wiley-Liss, Inc.

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Stereoselective binding of carbenicillin epimers to human serum albumin (1996)

Itoh, Tomoo ; Nakashima, Katashi ; Tsuda, Yasuyuki ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Chirality 8 (1996), S. 201-206

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ISSN: 0899-0042

Keywords: carbenicillin ; stereoselective ; binding ; HSA ; interaction ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Binding of carbenicillin (CBPC) epimers to human serum albumin (HSA) was found to be stereoselective. Epimer-epimer interaction was also observed in the binding to HSA. There were at least three binding sites on HSA for CBPC epimers, one of which (stereoselective site) was more in favor of S-CBPC than R-CBPC. At the stereoselective site, the binding constant of S-CBPC was approximately 4-fold greater than that of R-CBPC. The affinities to other binding sites (non-stereoselective sites) were similar between the epimers, and the affinity of S-CBPC of the non-stereoselective sites was much smaller than that for the stereoselective site.R-CBPC and S-CBPC appeared to displace each other at all the binding sites, i.e., the binding of the epimers was competitive at the non-stereoselective sites as well as at the stereoselective site. By using site marker ligands, it was revealed that CBPC epimers may bind to Site I (warfarin binding site), but not to Site II (diazepam binding site). A binding model with an assumption of competitive interactions at all the binding sites simulated the binding characteristics of CBPC epimers fairly well. © 1996 Wiley-Liss, Inc.

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4

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Use of Shed Snake Skin as a Model Membrane for in Vitro Percutaneous Penetration Studies: Comparison with Human Skin (1990)

Itoh, Tomoo ; Xia, Jun ; Magavi, Ravi ; [et al.]

Springer

Pharmaceutical research 7 (1990), S. 1042-1047

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ISSN: 1573-904X

Keywords: skin penetration ; transdermal ; shed snake skin ; functional group contribution ; Azone ; Elaphe obsoleta

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract The potential usefulness of shed snake skin as a model membrane for transdermal research was examined. There are similarities between shed snake skin and human stratum corneum in terms of structure, composition, lipid content, water permeability, etc. The permeability of various compounds and the contribution of several functional groups to the permeability were also found to be similar between shed snake skin and human skin. Moreover, the permeability of compounds through shed snake skin was increased by Azone, one of the most extensively studied transdermal penetration enhancers. Considering the similarities between shed snake skin and human skin, ease of storage and handling, and low cost, shed snake skin may offer a good model membrane for transdermal research.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1015943200982

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5

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Effects of Transdermal Penetration Enhancers on the Permeability of Shed Snakeskin (1992)

Itoh, Tomoo ; Wasinger, Lori ; Turunen, T. Marjukka ; [et al.]

Springer

Pharmaceutical research 9 (1992), S. 1168-1172

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ISSN: 1573-904X

Keywords: shed snakeskin ; Elaphe obsoleta ; transdermal ; penetration enhancer ; Azone ; lauryl alcohol

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract The effects of Azone and lauryl alcohol on the permeability of shed snakeskin were examined. Permeability of a variety of compounds through shed snakeskin was increased after Azone or lauryl alcohol pretreatment but the magnitude of the enhancement varied depending on the lipophilicity and the molecular size of the permeant. It was found that the shed snakeskin became more permeable after Azone or lauryl alcohol pretreatment, with a greater permeability increase for more hydrophilic and larger-molecular size permeants. As has been shown for untreated shed snakeskins, both the lipophilicity and the molecular size of the permeants are important in skin penetration and in determining the effects of transdermal penetration enhancers.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1015851805563

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6

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A Method to Predict the Percutaneous Permeability of Various Compounds: Shed Snake Skin as a Model Membrane (1990)

Itoh, Tomoo ; Magavi, Ravi ; Casady, Roger L. ; [et al.]

Springer

Pharmaceutical research 7 (1990), S. 1302-1306

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ISSN: 1573-904X

Keywords: skin penetration ; shed snake skin ; Elaphe obsoleta ; black rat snake ; distribution coefficient ; molecular weight ; permeability

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract Penetration of various compounds through shed snake skin was measured in vitro to examine the effect of lipophilicity and molecular size of a compound on permeability through this model membrane. The permeabilities were found to be controlled by the lipophilicity and the molecular size of the permeant. The smaller and the more lipophilic the compound, the greater the permeability. Equations have been developed to predict the permeability from the molecular weight and the distribution coefficient of a compound. Further, the lipophilicity of shed snake skin is similar to that of human skin and the response of shed snake skin to the molecular size of a permeant is more similar to human skin than to hairless mouse skin. Considering the similarities between shed snake skin and human stratum coraeum in terms of structure, composition, and permeability characteristics, the same considerations may apply to permeability through human stratum corneum.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1015902308676

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7

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Stereoselective pharmacokinetics of ibuprofen in rats: effect of enantiomer-enantiomer interaction in plasma protein binding (1997)

Itoh, Tomoo ; Maruyama, Jun ; Tsuda, Yasuyuki ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Chirality 9 (1997), S. 354-361

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ISSN: 0899-0042

Keywords: ibuprofen ; enantiomers ; stereoselective ; interactions ; plasma protein binding ; rat ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Stereoselective pharmacokinetics of ibuprofen (IB) enantiomers were studied in rats. Unidirectional conversion from R-ibuprofen (R-IB) to S-ibuprofen (S-IB) was observed following intravenous administration. S-IB concentrations in plasma following racemate administration were simulated according to a conventional compartmental model using the parameters obtained after the administration of individual enantiomers, and resulted in overestimation of S-IB concentrations.Binding of IB enantiomers measured in rat plasma was stereoselective, the binding of R-IB being more favorable than that of S-IB. Moreover, there are interactions between IB enantiomers in binding, which may cause the increase of distribution volumes of IB enantiomers in the presence of their antipodes. Hence simulated S-IB concentrations according to a conventional compartment model were significantly greater than those observed. Indeed, when the enantiomer-enantiomer interactions were taken into account, simulation of S-IB concentrations in plasma following racemate administration was in good agreement with observed values. Therefore, interactions between stereoisomers as well as dispositional stereoselectivity have to be considered when pharmacokinetics of stereoisomers after administration of the racemate are compared to those after administration of individual isomers. Chirality 9:354-361, 1997. © 1997 Wiley-Liss, Inc.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

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