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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of Drug Transport Through Tight-Junctional Pathway in Caco-2 Monolayer: Comparison with Isolated Rat Jejunum and Colon (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 523-528 
    Details
    ISSN: 1573-904X
    Keywords: intestinal transport ; rat jejunum ; rat ileum ; Caco-2 cells ; FITC-dextran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Drug transport through the tight-junctional pathway in Caco-2 monolayer was studied by examining the relationship between its permeability to hydrophilic drugs and membrane conductance. Compared with the rat isolated jejunum or colon, Caco-2 monolayer displayed high electrical resistance and low conductance, as well as low permeability to sulfanilic acid and FITC-dextran (M.W. 4000). However, there was a linear relationship between the drug permeability and partial Cl− ion conductance for Caco-2 monolayer, rat jejunum and colon. Hence, the permeability to those drugs per unit of Cl− conductance is similar in the three membranes, suggesting that the size (radius) of the tight-junctional pathway in the three membranes is similar. In addition, when the electrical resistance of Caco-2 monolayer was reduced to the same level as that of the jejunum or colon by pretreatment with disodium ethylenediamine-tetraacetate, its permeability to FITC-dextran became significantly higher than that of other membranes. Accordingly, the high resistance and the low permeability of Caco-2 monolayer compared with rat intestinal membrane may be due to structural differences between the membranes, rather than a difference in the tightness of the junction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016245711557
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of Drug Permeation Across Caco-2 Monolayer: Implication for Predicting In Vivo Drug Absorption (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 486-491 
    Details
    ISSN: 1573-904X
    Keywords: Caco-2 monolayer ; intestinal membrane ; drug lipophilicity ; in vitro drug permeability ; in vivo drug absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The aim of the present work is to characterize in vitro drug permeation processes across Caco-2 monolayer and to identify the advantages of this cultured cell system in predicting in vivo drug absorption after oral administration. Methods. The passive permeability of various drugs through Caco-2 monolayer was measured using Ussing-type chambers and compared with that of the isolated rat jejunum and colon. The in vivo drug permeability to the intestinal membrane was estimated by means of an intestinal perfusion study using the rat jejunum. Results. In Caco-2 monolayer, drug permeability increased with increasing drug lipophilicity and showed a good linear relationship with the in vivo permeability. In contrast, in the isolated jejunum and colon, the permeability of high lipophilic drugs was almost constant and, propranolol, a drug with the highest lipophilicity, hardly passed through the jejunal membrane in vitro. As a result, there was no significant relationship between in vitro and in vivo drug permeability in rat jejunum. However, the amount of drugs accumulated in the jejunal mucosa increased with increasing drug lipophilicity even under the in vitro condition. Conclusions. The permeation and the accumulation studies suggested that the rate-limiting process of in vitro permeation of lipophilic drugs through the intestinal membrane differs from that of in vivo drug absorption. On the other hand, drug permeation through Caco-2 monolayer, which consists of an epithelial cell layer and a supporting filter, is essentially the same process as that of in vivo drug absorption. We concluded that the simple monolayer structure of a cultured cell system provides a distinct advantage in predicting in vivo drug absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012103700981
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  • 3
    Electronic Resource
    Electronic Resource
    Assessment of Drug Disposition in the Perfused Rat Brain by Statistical Moment Analysis (1991)
    Springer
    Pharmaceutical research 8 (1991), S. 683-689 
    Details
    ISSN: 1573-904X
    Keywords: blood–brain barrier ; moment analysis ; brain perfusion ; indicator dilution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Drug disposition in the brain was investigated by statistical moment analysis using an improved in situ brain perfusion technique. The right cerebral hemisphere of the rat was perfused in situ. The drug and inulin were injected into the right internal carotid artery as a rapid bolus and the venous outflow curve at the posterior facial vein was obtained. The infusion rate was adjusted to minimize the flow of perfusion fluid into the left hemisphere. The obtained disposition parameters were characteristics and considered to reflect the physicochemical properties of each drug. Antipyrine showed a small degree of initial uptake. Therefore, its apparent distribution volume (V i) and apparent intrinsic clearance (CLint,i) were small. Diazepam showed large degrees of both influx and efflux and, thus, a large Vi. Water showed parameters intermediate between those of antipyrine and those of diazepam. Imipramine, desipramine, and propranolol showed a large CLint,i compared with those of the other drugs. The extraction ratio of propranolol significantly decreased with increasing concentrations of unlabeled propranolol in the perfusion fluid. These findings may be explained partly by the tissue binding of these drugs. In conclusion, the present method is useful for studying drug disposition in the brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015833513567
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetic Analysis of the Drug Permeation Process Across the Intestinal Epithelium (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 1646-1651 
    Details
    ISSN: 1573-904X
    Keywords: intestinal absorption ; vascular perfusion ; mean permeation time ; moment analysis ; diffusion model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The rat intestinal lumen and the blood vessel were simultaneously perfused to study drug permeation across the intestinal epithelium. On the basis of drug disappearance from the intestinal lumen and its appearance into the vascular outflow, the mean time required for permeation across the intestinal membrane (MPT) and the permeation clearance (CLp) were calculated. MPT values of water, antipyrine, propranolol, imipramine and mannitol, varied from 0.45 min to 9.91 min depending on their physicochemical property. From both MPT and CLp, five drugs were classified as being (i) highly and rapidly absorbed (water, antipyrine), (ii) highly but slowly absorbed (propranolol, imipramine) and (iii) low and slowly absorbed (mannitol). Permeation profiles of these drugs were analyzed based on the diffusion model which defined the parameter for each permeation process, i.e. partitioning to and diffusion through the epithelium and clearance into the blood flow. Propranolol and imipramine partitioned into the membrane at a higher level than the other drugs. However, the clearance of both drugs from the epithelium was extremely slow, suggesting that this process is the rate-limiting step in their permeation. On the other hand, the rate-limiting step in the permeation of water and antipyrine was found to be the diffusion process in the epithelial layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018926324682
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  • 5
    Electronic Resource
    Electronic Resource
    Study on drug metabolites by mass spectrometry. IVFor Part III, see Ref. 1. - metabolites of 2-(diethylamino) ethyltetrahydro-α-(1-naphthylmethyl)-2-furanpropionate oxalate in rats (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 66-72 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The determination of drug metabolites is very important in the biochemical field. However, the procedure for doing this has been very complicated in many cases. The major reason is because of the need for fairly large amounts of the samples. We have been studying procedures for the determination and identification by use of mass spectrometry, which usually gives a lot of information rapidly from very small amounts of the samples (below μg). In this paper, the metabolites excreted in urine and bile following oral administration of 2-(diethyamino)ethyl tetrahydro-α-(1-naphthylmethyl)-2-furanpropionate oxalate (1) in rats, were investigated by means of mass spectrometry and other techniques. The drug was not excreted unchanged in urine. Of the eight metabolites suspected to be present in urine and bile, the structures of three metabolites were elucidated to be tetrahydro-α-(1-naphthylmethyl)-2-furanpropionic acid (3) and α-(1-naphthylmethyl)-2-perhydro-5-oxofuranpropionic acid (4) in urine, and diethylaminoethanol (2) in bile. These metabolites might also be present as their structural isomers or conjugates.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200010114
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  • 6
    Electronic Resource
    Electronic Resource
    Mass spectrometry of medicines. Quantitative determination by direct probe inlet system mass chromatography (1978)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1978), S. 192-197 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A fundamental study was performed to establish a method of quantitative analysis using mass chromatography by the direct inlet system. The samples were aspirin, phenacetin and caffeine, which are often used as cold medicines, and barbital, allobarbital, phenobarbital and phenytoin which are difficult to analyse by gas chromatography in their intact states. N-acetylsulfamine and ethyl p-aminobenzoate were used as internal standards. Direct inlet mass chromatography was performed by an on-line system of the Shimadzu LKB-9000 and the GC-MSPAC 300. The ratio of the cumulative ions of certain peaks of sample and the internal standard was studied. It was found that, whether the sample is a pure reagent or a mixture, the ratio of cumulative ions of a peak specific to the sample and of a selected peak of the internal standard is proportional to the sample size, the error being less than ±3.5% for aspirin, phenacetin and caffeine, and less than ±2.7% for barbital, allobarbital and phenobarbital. The same relationship was observed for the phenobarbital and phenytoin mixed in rat plasma, the error being less than ±2.0%. It can be concluded that this method is applicable to the quantiative determination of medicines in urine, body fluids and other biological samples.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200050306
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