1,721,088 research outputs found
Alginate/chitosan microparticles for tamoxifen delivery to the limphatic system
No full textOral administration of the nonsteroidal anti-estrogen tamoxifen (TMX) is the treatment of choice for metastatic estrogen receptor-positive breast cancer. With the aim to improve TMX oral bioavailability and decrease its side effects, crosslinked alginate microparticles for the targeting to the lymphatic system by Peyer's patch (PP) uptake were developed and in vitro characterized. TMX was molecularly dispersed inside the microparticles and an electrostatic interaction involving the TMX tertiary amine was detected by rheological and FT-IR assays. Microparticles showed a size less than 3mum, then suitability to be taken up by M cells in PP and a positive surface charge. Moreover, TMX loading level as well as in vitro release behaviour was affected by the polymer network connected with the mannuronic/guluronic ratio of the alginate chains
L'analisi EDS nello studio di formulazioni farmaceutiche a rilascio modificato
No full textLa tecnica di analisi a dispersione di energia a raggi X (EDS) accoppiata all'uso del microscopio elettronico a scansione (SEM) può essere vantaggiosamente utilizzata in campo farmaceutico nello studio di formulazioni solide al fine di determinare la presenza e la distribuzione di elementi caratteristici
Preparation of lipospheres for cosmetic applications
No full textThis work aims to prepare and characterize lipospheres for the controlled release of cosmetic active ingredients which can be irritant to skin, such as glycolic acid, in order to reduce the skin damage and improve the effectiveness of this compound
Influenza di tensioattivi sull'idrolisi enzimatica in vitro del cloramfenicolo stearato
No full textE' stata studiata l'influenza di alcuni tensioattivi non ionici, cationici e anionici sull'idrolisi enzimatica in vitro dell'estere stearico del cloramfenicolo ad opera della lipasi pancreatica.E' stato possibile mettere in evidenza l'esistenza di una Concentrazione di Massima Idrolisi (CMI) che può coincidere o meno con la Concentrazione Micellare Critica (CMC) del tensioattivo usato e si è potuta distinguere e quantizzare l'azione del tensioattivo stesso sull'enzima e/o sul substrato
Intragastric behaviour of a multiple unit floating system
No full textThis work aims to assay in humans the intragastric behaviour of an air compartment multiple unit delivery system able to float just placed into the gastric fluid and obtainable by a new simple technological approach. The floating system used in this study had shown an excellent buoyancy ability in a previous "in vitro" investigation (3). The "in vivo" floating time and the gastric residence time (GRT) of the floating system were determined by X-ray photographs and compared with those of a non-floating system in both fasted and fed states
Crosslinked carboxymethylcellulose for the preparation of spherical matrices
No full textCrosslinked carboxymethylcellulose spherical matrices (beads) were prepared by using an in-liquid curing coating process with aluminium chloride as the curing agent. Variously concentrated aqueous solutions of sodium carboxymethylcellulose of three different nominal viscosity grades were used to obtain beans loaded with ambroxol hydrochloride. To characterize the beads their behaviour in,cater was evaluated with respect to preparative variables, i.e. nominal viscosity grade and concentration of the polymer. The swelling process of beads prepared by varying the nominal viscosity grade of sodium carboxymethylcellulose was greatly affected by the presence of the drug and the residual amount of crosslinking agent (free AlCl3). In fact, only by removing the drug and free AlCl3 it was possible to observe that the increase of polymer nominal viscosity grade, Le. molecular rt eight, slowed the early stage of the swelling process. This phenomenon may be explained by increased viscosity of the gel and decreased porosity of the beads. Although the increase of polymer molecular weight reduced matrix porosity it did not modify the drug release process, which occurred rapidly The increase of polymer concentration reduced the residual amount of crosslinking agent. This fact, combined with the greater compactness of the matrix, resulted in a significant decrease in the extent of swelling and in the drug release rate of beads obtained using the highest concentration of the polymer The evaluation of the beads as oral delivery, systems showed that the drug release from beads prepared using the highest concentration,fns rapid in simulated gastric fluid, but extended in simulated intestinal fluid. Moreover in simulated intestinal fluid, a nearly zero-order kinetics was obtained due to the erosion of the swollen matrix. Thus, by development of an appropriate delivery system, a prolonged and constant rate release in the intestinal tr aci may be achieved
Cosmetici e informazione
No full textE' stata valutata la terminologia che descrive le caratteristiche di prodotti cosmetici in confronto alla terminologia ammessa secondo l'attuale legislazione, al fine di verificare la corretta informazione fornita all'utilizzatore
Skin tolerance and cell renewall induced by lipospheres loaded with glycolic acid
No full textThe present study has involved the development of lipospheres loaded with glycolic acid in order to evaluete the effect on the skin damage and effectiveness of such a compound.
Assays for liposphere skin tolerance and cell renewal ability in humans demonstrated the less irritation potemtial and the sameefficacy provided by unencpsulated glycolic acid
Microsfere di alginato preparate per spray-drying per la veicolazione di macromolecole
No full textSono state preparate microsfere di alginato mediante un processo di reticolazione di microparticelle, preparate per spray-drying, che ha coinvolto in successione le due unità costituenti il polisaccaride: le unità guluroniche, reticolate con Ca2+; le unità mannuroniche, reticolate con PEI+. Le microsfere ottenute, indipendentemente dal valore M/G, presentano in fluido gastrico un rilascio modesto della macromolecola caricata. Le microsfere a base di alginato a basso M/G monoreticolate con Ca2+ presentano, in fluido intestinale, un rilascio della macromolecola caricata più sostenuto rispetto a quello presentato dalle microsfere di alginato ad alto M/G. La reticolazione per fasi successive dell'alginato ad alto M/G ha portato alla formazione di microsfere bireticolate che rilasciano la macromolecola in modo più graduale nel tempo in funzione della concentrazione di Ca2+ e PEI+. Poichè una concentrazione troppo elevata di Ca2+ può interferire nella reticolazione dei gruppi mannuronici da parte del PEI+, è necessario dosare le concentrazioni relative dei reattanti. Pertanto, la reticolazione mediante Ca2+ e PEI+ effettuata su microparticelle di alginato permette di ottenere microsfere capaci di veicolare macromolecole e modularne il rilascio nel tratto intestinale
Calcium alginate membrane coated matrices as oral drug delivery system
No full textA translucent coat of calcium alginate with a wrinkled appearance was obtained around the PVA matrices. Increase in coating time led to an increase in the coat thickness and a decrease in drug content, also, a certain amount of drug appeared in the coat.The drug release was affected by the thickness and the pH-dependent behaviour of the coat. In fact, the drug was released from the swollen matrix through the intact coat in simulated gastric fluid and through the gelatinized coat in simulated intestinal fluid giving linear profiles, after a burst effect
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