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  • transdermal delivery  (2)
  • confocal laser scanning microscopy  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Estradiol Permeation from Nonionic Surfactant Vesicles Through Human Stratum Corneum in Vitro (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 659-664 
    Details
    ISSN: 1573-904X
    Keywords: niosomes ; nonionic surfactant vesicles ; estradiol ; transdermal delivery ; stratum corneum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The permeation of estradiol from vesicular formulations through human stratum corneum was studied in vitro. The vesicles were composed of nonionic n-alkyl polyoxyethylene ether surfactants (CnEOm). The thermodynamic activity of estradiol present in each formulation was kept constant by saturating all formulations with estradiol. The effects of both the particle size and the composition of the formulation on estradiol permeation across excised human stratum corneum were investigated. Stratum corneum that was pre-treated with empty surfactant carriers allowed for significantly higher estradiol fluxes compared with untreated stratum corneum. However, estradiol fluxes obtained in these pretreatment experiments appeared to be significantly lower than those obtained by the direct application of the estradiol-saturated carrier formulation on top of the stratum corneum. Furthermore, in the case of pretreatment of the stratum corneum, an increase in carrier size resulted in a decrease in estradiol flux. For direct application the opposite was found. Two mechanisms are proposed to play an important role in vesicle–skin interactions, i.e., the penetration enhancing effect of surfactant molecules and the effect of the vesicular structures that are most likely caused by adsorption of the vesicles at the stratum corneum–suspension interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018963910260
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Diffusion Rates and Transport Pathways of Fluorescein Isothiocyanate (FITC)-Labeled Model Compounds Through Buccal Epithelium (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 83-89 
    Details
    ISSN: 1573-904X
    Keywords: buccal drug delivery ; buccal mucosa ; fluorescein isothiocyanate-labeled dextrans ; confocal laser scanning microscopy ; drug transport pathways
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The aim of this study was to characterize transport of FITC-labeled dextrans of different molecular weights as model compounds for peptides and proteins through buccal mucosa. The penetration of these dextrans through porcine buccal mucosa (a nonkeratinized epithelium, comparable to human buccal mucosa) was investigated by measuring transbuccal fluxes and by analyzing the distribution of the fluorescent probe in the epithelium, using confocal laser scanning microscopy for visualizing permeation pathways. The results revealed that passage of porcine buccal epithelium by hydrophilic compounds such as the FITC-dextrans is restricted to permeants with a molecular weight lower than 20 kDa. The permeabilities of buccal mucosa for the 4- and 10-kDa FITC-dextran (of the order of 10−8 cm/sec) were not significantly different from each other or from the much smaller compound FITC. The confocal images of the distribution pattern of FITC-dextrans showed that the paracellular route is the major pathway through buccal epithelium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018949828548
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    lontophoretic Delivery of Apomorphine II: An In Vivo Study in Patients with Parkinson's Disease (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 1804-1810 
    Details
    ISSN: 1573-904X
    Keywords: iontophoresis ; Parkinson's disease ; human ; pharmacodynamics ; transdermal delivery ; apomorphine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Transdermal transport rates of the dopamine agonist R-apomorphine were determined in patients with idiopathic Parkinson's disease (IPD). Apomorphine was applied by iontophoresis at two current densities. Methods. In ten patients apomorphine was applied passively for one hour. Thereafter, in the first five patients, a current density of 250 μA.cm−2 was applied for one hour and a current density of 375 μA.cm−2 in the second group. The individual pharmacokinetic parameters were obtained separately following a 15-minute zero-order intravenous infusion of 30 μg.kg−1. Skin resistance was measured during current delivery. Current-induced irritation was measured by Laser Doppler Flowmetry (LDF). The pharmacodynamics were quantified by a unilateral tapping score. Qualitative clinical improvements (decreased tremor, rigidity or cramp) were also recorded. Results. In all patients increasing plasma concentrations of R-apomorphine were found during the interval of current application. The maximum concentrations that were attained were related to the applied current density: 1.3 ± 0.6 ng.ml−1 at 250 μA.cm−2 and 2.5 ± 0.7 ng.ml−1 at 375 μA.cm−2. When the current was switched off all concentrations returned to baseline values in about 90 minutes. By mathematical deconvolution of the profiles it was shown that steady-state fluxes were reached within the one-hour interval of current driven transport. Steady-state fluxes were calculated to be 69 ± 30 nmol.cm−2.h−1 at 250 μA.cm−2 and 114 ± 34 nmol.cm−2.h−1 at 375 μA.cm−2. Individual drug input rates were inversely related to the overall resistance. Significantly elevated LDF values were found after patch removal, indicating mild current induced erythema. Only subtherapeutic plasma concentrations were obtained in all patients except for one. Conclusions. The results show that current-dependent delivery of apomorphine is possible in vivo at acceptable levels of skin irritation. Excellent correlation was found between the calculatedin vivo transport rates and the rates that were previously obtained in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012152401715
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    Paper (German National Licenses)
    Fulltext
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