1,721,178 research outputs found
Vescicole di tensioattivo non-ionico quali delivery systems di farmaci per via inalatoria
No full textHybrid niosome complexation in the presence of oppositely charged polyions
No full textWe have investigated the formation of complexes between negatively charged niosomal vesicles (hybrid niosomes), built up by dicethylphosphate [DCP], Tween 20 and Cholesterol, and three linear differently charged cationic polyions, such as alpha-polylysine, epsilon-polylysine, and polyethylvinylpyridinium bromide [PEVP], with two different substitution degrees. Our aim is to investigate the interaction mechanism between anionic-nonionic vesicles (hybrid niosomes) and linear polycations, characterizing the resulting aggregates in view of possible applications of these composite colloidal particles as vectors for multidrug delivery. In order to explore the aggregation behavior of the complexes and to gain information on the stability of the single niosomal vesicles within the aggregates, we employed dynamic light scattering (DLS), laser Doppler electrophoretic measurements, and fluorescence measurement techniques. The overall phenomenology is well described in terms of the re-entrant condensation and charge inversion behavior, observed in different colloidal systems. The aggregate size and overall charge depend on the charge ratio between vesicles and polyions, and the aggregates reach their maximum size at the point of charge inversion (re-entrant condensation). While the overall phenomenology is similar for all three polycations investigated, the stability and the integrity of the hybrid niosomal vesicles forming the aggregates strongly depend on the chemical structure of the polycations. The role of the polycations in the aggregation process is discussed by identifying specific interactions with the niosomal membrane, pointing out their importance for possible applications as drug delivery vectors
LIPOSOMAL APPROACH TO PHARMACEUTICS
No full textEfficient and safe drug delivery has always been a challenge in therapy and diagnostics. The use of nanotechnology, as well as the development of nanocarriers for drug delivery, received great attention according to the evidence that they can theoretically act as “magic bullets” capable to hit the target cells while sparing normal tissues and organs. Liposomes are suitable as carriers of both hydrophilic and lipophilic drugs and are able to deliver drugs to the target site.
The vesicle properties are specifically dictated by size, shape, and surface chemistry which are able to modify the intrinsic pharmacokinetics of the drug and, eventually, the drug targeting to the pathological areas.
Liposomes can be developed in different approach to pharmaceutics. According to this, in our laboratory, liposomes have been proposed as biomembrane model in order to study the interaction between surfactant vesicles and liposomes, since it is very difficult to directly observe the membrane fusion due to the complexity of biomembranes and the high speed of the process (1). Furthermore our research involves the “classic” use of liposomes as drug delivery systems. For example they have been studied to obtain an efficient brain delivery of prodrugs to enhance the extracellular levels of L-Dopa and Dopamine in rat striatum of freely moving rat (2). Maleic and fumaric diamides of (O,O-diacetyl)- L-Dopa-methylester, synthesized in order to attenuate marked fluctuations of L-Dopa plasma levels and to overcome the problem of low bioavailability of L-Dopa, have been entrapped in liposomal formulations to obtain chemical stability in aqueous buffer solutions, slow release of LD in human plasma and sustained delivery of Dopamine in rat striatal dialysate (3). With the aim to provide a protection against chemical degradation and enzymatic metabolism and, consequently, to get a high prodrug quantity able to cross the Blood Brain Barrier, liposomal formulations of 2-amino-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-3-phenyl-propionamide (DOPH) were prepared and characterized (4). Polysaccharide-coated liposomes have been proposed as carrier of peptide drug by the oral route because they are able to minimize the disruptive influences on peptide drugs of gastrointestinal fluids. In particular, a modified polysaccharide, O-palmitoylscleroglucan (PSCG), was synthesized and used to coat unilamellar liposomes for oral delivery of Leuprolide, a synthetic superpotent agonist of luteinizing hormone releasing hormone receptor (5). In collaboration with the Centre for Surgical Technologies at the Faculty of Medicine of the Katholieke Universiteit of Leuven (Belgium), thermosensitive liposomes have been prepared to deliver the Cytotoxic Necrotizing Factor 1 (CNF-1) toward lung tissues, with an effective approach against the Congenital Diaphragmatic Hernia (CDH). These carriers are able to release drugs/proteins due to the hyperthermia, as a consequence of lung tissues inflammation. The preliminary studies have shown the safety of these structures in foetal rats and rabbits with CDH. Finally, in our laboratory, the phospholipidic shell was used to prepare novel nanobbubles, NBs (6) - ). These structures can act as theranostic agents. The preclinical experiments, developed in collaboration with the Queens Medical Research Institute at the University of Edinburgh, were carried out to demonstrate that ultrasound-mediated NBs destruction has the potential to open the BBB tight junctions and trigger therapeutic agent deposition in the brain. The results are very promising and suggest the possible use of NBs in the theranostic fields
Model lipophilic formulation of retinil palmitate: influence of conservative agents on light-induced degradation
No full textVitamin A is widely employed in pharmaceuticals and cosmetics. The all-trans (AT) isomer (100% of biological potency) is sensible to different factors, such as light, heat and formulation components, leading to its degradation or isomerization. The main objective of this work was to study, in model cosmetic lipophilic vehicles, the degradation of retinyl palmitate (RetP) to the less active cis-isomers in presence of widely used conservative agents (propyl gallate and Vitamin E). Two lipophilic phases were used (liquid paraffin and almond oil) because liquid paraffin, almost composed of satured hydrocarbons, is not degraded by light exposure, while almond oil, containing several double bonds, could interfere with light-induced degradative process of RetP. In the first phase, the more suitable analytical method was chosen between normal and reverse phase HPLC to follow the degradation of RetP. In the second phase, RetP light-induced degradation was studied to simulate storage condition effect on cosmetic products ageing. The results showed that: (a) the reverse phase HPLC technique, unable to separate the all-trans from the 13-cis and 9-cis isomers, derived by Vitamin A isomerization, leads to an incorrect quantitation of RetP; (b) the lipophilic vehicle influences the isomerization–degradation process; (c) the conservative agents do not protect from degradation. © 2003 Elsevier B.V. All rights reserved
DLS Characterization of Non-Ionic Surfactant Vesicles for Potential Nose to Brain Application
No full textThe aim of this paper is the preparation and characterization of drug delivery systems for a potential brain delivery
by intranasal administration. It is possible to reach the central nervous system with alternative routes through which therapeutic
agents can bypass the blood brain barrier: that is the nasal administration. Intranasal drug administration is non-invasive and it
could be a promising drug delivery method for patients who suffer from chronic and crippling Central Nervous System diseases.
Among the formulation strategies for enhanced nose to brain drug delivery, the use of colloidal carriers has became a
revolutionary approach. The success of a therapeutic strategy by using nanocarriers depends on their ability to entrap drugs, to
penetrate through anatomical barriers, to efficiently release the incorporated drugs, to show a good stability in nanometric size
range and good biocompatibility. The use of vesicular systems (niosomes), in nose to brain delivery is here presented. One of the
major problems associated with nasal administration is the rapid removal of drugs or drug delivery systems, from the deposition
site through mucociliary clearance. This effect is responsible of reduction of contact time between drug or drug delivery systems
and nasal epithelium. This problem could be solved by coating nanocarriers with a mucoadhesive agent: chitosan. In this paper
the preparation and characterization of hybrid niosomes by Tween 20 and Tween 21 together with dicetyl phosphate or Span 20
and the cationic polyelectrolyte chitosan are described in order to obtain intranasal drug delivery systems. In particular through
dynamic light scattering, laser Doppler electrophoresis and fluorescence measurements the aggregation behavior between
vesicles and polyelectrolyte can be monitored. Overall phenomenology is well described in terms of the re-entrant condensation
and charge inversion behavior, observed in different colloidal systems. The physical stability of hybrid niosomes obtained by the
three different surfactants was also evaluated
Nanomedicines and nanocarriers in clinical trials: surfing through regulatory requirements and physico-chemical critical quality attributes
No full textElucidation of physical-chemical characteristics of investigational medicinal products should be established with suitable methodology. Characterization of nanomedicines and nanocarriers in clinical trials may require the definition of additional specific properties depending on the nature of the nanostructures or nanomaterials composing the investigational medicinal product. The availability of regulatory requirements and guidelines is investigated focusing on critical quality attributes for nanomedicines and nanocarriers, mapping them in a clinical trial setting. Current regulatory challenges and issues are highlighted. The increasing complexity of nanostructures, the innovative connotation of applied nanotechnology, and the lack in capillarity or misalignment of relevant guidelines and terminology may lead to a potential not standardized approach in the characterization of nanomedicines and nanocarriers in clinical trials and delays in the approval process. Further efforts and a proactive approach from a regulatory standpoint would be desirable to surf the wave of innovation that impact nanomedicines and nanocarriers in clinical trials, in order to support clinical drug development capitalizing on technological advances and still ensuring a strong regulatory framework. GRAPHICAL ABSTRACT: [Image: see text
Non-ionic surfactant vesicles for ammonium glycyrrhizinate delivery: in vitro characterization and in vivo evaluation on mice oedema
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