Razvoj matriksnih sustava za transdermalnu isporuku pentazocina: In vitro/in vivo ispitivanje

The present study aimed to develop hydroxypropyl methylcellulose based transdermal delivery of pentazocine. In formulations containing lower proportions of polymer, the drug released followed the Higuchi kinetics while, with an increase in polymer content, it followed the zero-order release kinetics. Release exponent (n) values imply that the release of pentazocine from matrices was non-Fickian. FT-IR, DSC and XRD studies indicated no interaction between drug and polymer. The in vitro dissolution rate constant, dissolution half-life and pharmacokinetic parameters (Cmax, tmax, AUC(s), t1/2, Kel, and MRT) were evaluated statistically by two-way ANOVA. A significant difference was observed between but not within the tested products. Statistically, a good correlation was found between per cent of drug absorbed from patches vs. Cmax, and AUC(s). A good correlation was also observed when per cent drug released was correlated with the blood drug concentration obtained at the same time point. The results of this study indicate that the polymeric matrix films of pentazocine hold potential for transdermal drug delivery.U radu je opisan razvoj transdermalnih sustava na bazi hidroksipropil metilceluloze za isporuku pentazocina. U pripravcima koji sadrže manje udjele polimera, otpuštanje lijeka slijedilo je Higuchijevu kinetiku. Međutim, ako je udio polimera veći oslobađanje je najbolje odgovaralo kinetici nultog reda. Vrijednost eksponenta n implicira da oslobađanje pentazocina iz matriksa nije po Fickovom zakonu. FT-IR, DSC i X RD studije ukazuju da nema interakcije između ljekovite tvari i polimera. In vitro konstanta oslobađanja, poluvrijeme oslobađanja i farmakokinetički parametri (Cmax, tmax, AUC(s), t1/2, Kel, i MRT) procijenjeni su statistički koristeći ANOVA program. Značajna razlika primijećena je između, ali ne i unutar testiranih pripravaka. Pronađena je dobra korelacija između lijeka apsorbiranog iz flastera i Cmax i AUC(s) te oslobođenog lijeka i koncentracije lijeka u krvi. Rezultati ukazuju da su polimerni matriksni filmovi pentazocina potencijalno dobri sustavi za transdermalnu primjenu lijeka

Magnetische Struktur, lokale elektronische Zustaende, Kationenverteilung sowie Reaktionskinetik und Reaktionsmechanismen in Spinellen, Olivinen und Hexaferriten, untersucht mit Kern- und Teilchenstrahlung Schlussbericht

Available from TIB Hannover: DtF QN1(49,9) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Arrangement of ceramide [EOS] in a stratum corneum lipid model matrix new aspects revealed by neutron diffraction studies

The lipid matrix in stratum corneum SC plays a key role in the barrier function of the mammalian skin. The major lipids are ceramides CER , cholesterol CHOL and free fatty acids FFA . Especially the unique structured x acylceramide CER[EOS] is regarded to be essential for skin barrier properties by inducing the formation of a long periodicity phase of 130 A amp; 730; LPP . In the present study, the arrangement of CER[EOS], either mixed with CER[AP] and CHOL or with CER[AP], CHOL and palmitic acid PA , inside a SC lipid model membrane has been studied for the amp; 64257;rst time by neutron diffraction. For a mixed CER[EOS] CER[AP] CHOL membrane in a partly dehydrated state, the internal membrane nanostructure, i.e. the neutron scattering length density pro amp; 64257;le in the direction normal to the surface, was obtained by Fourier synthesis from the experimental diffraction patterns. The membrane repeat distance is equal to that of the formerly used SC lipid model system composed of CER[AP] CHOL PA ChS. By comparing both the neutron scattering length density pro amp; 64257;les, a possible arrangement of synthetic long chain CER[EOS] molecules inside a SC lipid model matrix is suggested. The analysis of the internal membrane nanostructure implies that one CER[EOS] molecule penetrates from one membrane layer into an adjacent layer. A 130 A amp; 730; periodicity phase could not be observed under experimental conditions, either in CER CHOL mixtures or in CER CHOL FFA mixture. CER[EOS] can be arranged inside a phase with a repeat unit of 45.2 A amp; 730; which is predominately formed by short chain CER[AP] with distinct polarity

Influence of trehalose on the structure of unilamellar DMPC vesicles

The influence of trehalose on the structure and properties of unilamellar ULVs and multilamellar MLVs dimyristoylphosphatidylcholine DMPC vesicles was studied using neutron and X ray scattering, Raman spectroscopy, and differential scanning calorimetry. Trehalose solutions ranging from 0 to 30 w w have been used. It was found that trehalose increases the main phase transition temperature of the MLVs, but has no influence on the main phase transition temperature of the ULVs. In the liquid crystalline phase, the DMPC membrane thickness decreases by a value of 3.1 at 20 trehalose. The intermembrane space increases by a value of about 26 at 30 trehalose. Due to the X ray contrast variation caused by trehalose, it was possible to measure the thickness of the DMPC hydrocarbon chains directly by using X ray scatterin