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  • 1
    ISSN: 1573-904X
    Schlagwort(e): paclitaxel ; emulsions ; filter-sterization ; particle size ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Purpose. Paclitaxel is currently administered i.v. as a slow infusion of asolution of the drug in an ethanol:surfactant:saline admixture. However,poor solubilization and toxicity are associated with this drug therapy.Alternative drug delivery systems, including parenteral emulsions, areunder development in recent years to reduce drug toxicity, improveefficacy and eliminate premedication. Methods. Paclitaxel emulsions were prepared by high-shearhomogenization. The particle size of the emulsions was measured by dynamiclight scattering. Drug concentration was quantified by HPLC and invitro drug release was monitored by membrane dialysis. The physicalstability of emulsions was monitored by particle size changes in boththe mean droplet diameter and 99% cumulative distribution. Paclitaxelpotency and changes in the concentration of known degradants wereused as chemical stability indicators. Single dose acute toxicity studieswere conducted in healthy mice and efficacy studies in B16 melanomatumor-bearing mice. Results. QW8184, a physically and chemically stable sub-micronoil-in-water (o/w) emulsion of paclitaxel, can be prepared at high drugloading (8-10 mg/mL) having a mean droplet diameter of 〈100 nmand 99% cumulative particle size distribution of 〈200 nm. In vitro release studies demonstrated low and sustained drug release both inthe presence and absence of human serum albumin. Based on singledose acute toxicity studies, QW8184 is well tolerated both in miceand rats with about a 3-fold increase in the maximum-tolerated-dose(MTD) over the current marketed drug formulation. Using the B16mouse melanoma model, a significant improvement in drug efficacywas observed with QW8184 over Taxol®. Conclusions. QW8184, a stable sub-micron o/w emulsion of paclitaxelhas been developed that can be filter-sterilized and administered i.v.as a bolus dose. When compared to Taxol®, this emulsion exhibitedreduced toxicity and improved efficacy most likely due to thecomposition and dependent physicochemical characteristics of the emulsion.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Pharmaceutical research 12 (1995), S. 1561-1572 
    ISSN: 1573-904X
    Schlagwort(e): self-emulsifying systems ; microemulsions ; drug dissolution ; membrane permeability ; intestinal absorption ; medium-chain glycerides ; enhancer ; peptide delivery
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Purpose. This review highlights the state-of-the-art in pharmaceutical microemulsions with emphasis on self-emulsifying systems, from both a physical and biopharmaceutical perspective. Although these systems have several pharmaceutical applications, this review is primarily focused on their potential for oral drug delivery and intestinal absorption improvement. Methods. Physicochemical characteristics and formulation design based on drug solubility and membrane permeability are discussed. Results. Case studies in which lipid microemulsions have successfully been used to improve drug solubilization/dissolution and/or intestinal absorption of poorly absorbed drugs/peptides are presented. Conclusions. Drug development issues such as commercial viability, mechanisms involved, range of applicability, safety, scale-up and manufacture are outlined, and future research and development efforts to address these issues are discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1573-904X
    Schlagwort(e): w/o microemulsions ; medium-chain glycerides ; medium-chain fatty acids/salts ; enhancer ; intestinal absorption ; calcein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Purpose. Water-in-oil (w/o) microemulsions have been developed which, in addition to non-ionic medium-chain glycerides, incorporate ionic lipids, primarily medium-chain fatty acids, such as caprylic (C8) capric (C10) and lauric (C12) acids and their corresponding sodium salts. The absorption enhancing activity of w/o microemulsions incorporating these lipids was evaluated in the rat using Calcein (MW = 623) a water-soluble and poorly absorbed marker molecule. Methods. Phase diagrams were constructed where C8/C10 or C12 fatty acids were treated as lipophilic surfactants and their sodium salts as hydrophilic ones. The anesthetised rat model was employed to evaluate Calcein absorption upon a single intraduodenal administration from a solution and the various w/o microemulsions. Results. A wide range of clear and transparent w/o microemulsions were obtained at ambient temperature either in liquid or solid form when a fixed blend of medium chain fatty acid/salt was titrated by a fixed ratio of the oil containing the oil-soluble mono- and diglycerides and deionized water or physiological saline. Upon intraduodenal administration in the anesthetised rat, the absorption of Calcein was improved from about 2% in aqueous solution up to about 37% in w/o microemulsions. Solid and liquid formulations were equally effective in improving bioavailability. The absorption enhancement activity of the fatty acids/salts followed the order C8 ≈ C10 〉 C12. Absorption enhancement of Calcein was significantly reduced in the absence or presence of low levels of C8/C10 mono-/diglycerides. Conclusions. These results further support the use of medium-chain glycerides and fatty acids/salts in microemulsion formulations to improve intestinal absorption of water-soluble compounds.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1573-904X
    Schlagwort(e): water-in-oil microemulsions ; medium-chain glycerides ; enhancer ; intestinal absorption ; fibrinogen receptor antagonist
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract We developed self-emulsifying water-in-oil (w/o) microemulsions incorporating medium-chain glycerides and measured their conductance, viscosity, refractive index and particle size. Formulation of Calcein (a water-soluble marker molecule, MW = 623), or SK&F 106760 (a water-soluble RGD peptide, MW = 634) in a w/o microemulsion having a composition of Captex 355/Capmul MCM/Tween 80/Aqueous (65/22/10/3, % w/w), resulted in significant bioavailabil-ity enhancement in rats relative to their aqueous formulations. Upon intraduodenal administration the bioavailability was enhanced from 2% for Calcein in isotonic Tris, pH 7.4 to 45% in the microemulsion and from 0.5% for SK&F 106760 in physiological saline to 27% in the microemulsion formulation. The microemulsion did not induce gross changes in GI mucosa at a dosing volume of 3.3 ml/kg. These results suggest that water-in-oil microemulsion systems may be utilized for enhancement of intestinal drug absorption.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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