1,721,173 research outputs found
Bioactive Molecules from Vegetable Sources for the Treatment of Cutaneous Pathologies and Disorders Part 2
No full textNo abstract availabl
Acyclovir delivery systems
No full textHerpes viruses (herpes simplex, varicella zoster, cytomegalovirus) are the main cause agents of a wide variety of human infections. Although the development of successful antiviral agents against Herpes viruses’ infections had been slow until the last decade; progresses in the production of delivery systems for acyclovir are a quite promising alternative. The present review focuses on progresses in developing carriers or formulations for the delivery of acyclovir by different routes of administration
Distamycins: strategies for possible enhancement of activity and specificity
No full textThe present review focused on the strategies aimed to possibly solve toxicity problems of distamycins. Distamycins are compounds characterized by an oligopeptidic pyrrolocarbamoyl frame ending with an amidino moiety. This class of compounds displays antiviral and antibiotic activity and shows interesting antiprotozoal activity related to the ability to reversibly bind to the minor groove of DNA with a high selectivity for TA-rich sequences. In consideration of their potential therapeutic properties, the synthesis of new distamycin derivatives and especially the development of controlled delivery strategies, could lead to important advantages in the clinical use of these molecules, possibly overcoming or mitigating the low solubility, specificity and toxicity problems associated with their use. To these aims an ensemble of the main synthetic distamycin derived compounds and of the potential drug delivery systems for distamycins described in literature is reviewed
NEW DELIVERY SYSTEMS FOR RETINOIDS APPLICATION
No full textVitamin A is essential for the growth, differentiation and function of epithelial tissue. Low serum retinol levels have been associated with an increased risk of malignant disease. Natural and synthetic retinoids are active in several types of premalignant skin lesions such as keratoacanthoma, actinic keratosis and basal cell carcinoma One of the less toxic vitamin A analogues studied is fenretinide (4 hydroxypropyl phenyl retinamide), a synthetic amide derivative of all-trans- retinoic acid. It has been applied in the chemoprevention and in the treatment of different types of malignancies including breast cancer, neuroblastoma, prostate, ovary, and skin tumours (e.g. basal cell carcinoma) and some other skin diseases (e.g. actinic keratosis).
Advanced topical formulations to be applied on skin should be desirable in order to locally treat cutaneous pathologies. Scientific researches are always in progress in order to develop new specialized vehicles able to assure targeted delivery of actives, minimizing at the same time toxic systemic effects. Solid Lipid Nanoparticles (SLN) have been firstly designed for i.v. administration and recently investigated for peroral and transdermal application. Their solid matrix should be able to protect chemically labile agents from degradation and to modulate drug release profiles. Skin care studies performed by the use of SLN indicate an increase in skin hydration and a reduction in wrinkle depth, moreover SLN can improve uptake of cosmetic agents. The lecithin organogel consists of reversed polymer-like micelles. They are generated from the initial spherical ones by dissolving trace amounts of water in a nonaqueous solution. The micellar aggregates entangle, forming a temporal three-dimensional network in the bulk phase. These gel-like reverse micellar systems are particularly interesting for dermocosmetic applications due to their ability to solubilize substances with different chemico-physical properties, their thermodynamic stability and their biocompatibility. Niosomes, vesicles prepared by non-ionic surfactants, have recently been largely proposed as drug delivery systems. This class of vesicles, structurally very similar to liposomes, was introduced in reason of the higher chemical stability of the surfactants compared to that of phospholipids.
In particular the present study concerns the design and characterization of SLN, organogels and niosomes as vehicles for retinoids such as fenretinide and rethinyl acetate
Design and characterization of fenretinide containing organogels
No full textThe stable, transparent, organogels, which are prepared by adding a minute amount of water to a solution of lecithin in biocompatible oil, are here studied as matrices for solubilization and percutaneous delivery of fenretinide (4 hydroxypropyl phenyl retinamide, 4HPR) a retinoic acid derivative. The influence of different type of oil, content of water and presence of hyaluronic acid was studied on gel properties. Rheology studies were carried out in order to detect the effect of these variables on gel viscosity. 4HPR diffusion from the different organogels was determined by in vitro Franz cell.
It was found that diffusion coefficients (Jn) of 4HPR incorporated in organogels are about five fold lower than Jn of 4HPR in organic solution.
Stability and shelf life stability studies demonstrate that 4HPR incorporated in organogels doesn’t degrade and that organogels maintain 90% of 4HPR stability for periods up to 4 months
Hyaluronan-based microspheres as tools for drug delivery: a comparative study
No full textThe present paper describes the production of biodegradable microparticles using different hyaluronan polymers, such as native
hyaluronan, the esterified derivative of hyaluronan Hyaff 11p50 (where50%of the carboxy groups of hyaluronic acid are esterified
with benzyl alcohol) and the autocross-linked polymer (ACP) internally esterified derivative of hyaluronan, by solvent evaporation
and spray-drying methods. As model drugs cromolyn sodium salt, metronidazole and prednisolone hemisuccinate sodium salt
were employed. The influence of polymer and preparation procedure has been evaluated on microparticle characteristics (i.e.
morphology and encapsulation yield) and on the drug release profiles. The use of solvent evaporation method, a polymeric matrix
constituted of Hyaff 11p50 3% (w/v), a dispersing phase constituted of 80 g of mineral oil (w/o ratio: 0.1), Span 85 0.1% (w/w)
as stabilizer, and a stirring speed of 700 rpm resulted in the production of microspheres characterized by spherical shape, absence
of aggregates, a mean diameter of 6.4 m and a recovery of 90% (w/w). The production of drug containing microspheres led to
an increase of mean diameter of microspheres and to high encapsulation yields. Moreover in vitro models have demonstrated
that in all cases drugs were released from Hyaff 11p50 microspheres in a controlled fashion. Finally mathematical analysis of
the drug release modalities has evidenced that drug release from Hyaff 11p50 microspheres is more consistent with kinetics of
the diffusion rather than of the dissolution type
Ethosomes and liposomes as topical vehicles for azelaic acid: A preformulation study
No full textThe basic properties and the in vitro release rate kinetics of azelaic acid (AA) alternatively vehiculated in different phospholipid based vesicles, such as ethosomes or liposomes, were investigated. Ethosomes were produced by a simple method based on addition of an aqueous phase to an ethanol solution (comprised between 20 and 45 % v/v) of soy phosphatidyl choline (5 % w/w) and AA (0.2 % w/w) under mechanical stirring. Liposomes were obtained by the same composition in the absence of ethanol with the reverse-phase evaporation method. Vesicle size was measured by Photon Correlation Spetroscopy (PCS) evidencing smaller mean diameters and narrower dimensional distributions in the case of ethosomes with respect to liposomes. In order to obtain homogeneously sized vesicles, both ethosomal and liposomal dispersions were extruded through polycarbonate membranes with pores of calibrated diameter (400 and 200 nm). Vesicles morphology was characterized by freeze-fracture Scanning Electron Microscopy (SEM) showing the presence of unilamellar vesicles both in liposome and in ethosome based dispersions.
Free energy measurements of the vesicle bilayers were conducted by Differential Scanning Calorimetry (DSC). AA diffusion from ethosomal or liposomal dispersions and from ethosomes and liposomes incorporated in a viscous gel was investigated by a Franz cell assembled with synthetic membranes. Release rate was more rapid from ethosomal with respect to liposomal systems, in particular ethosomes produced by the highest ethanol concentration released AA more rapidly, the same trend was found using viscous forms
Lyophilized niosomes and liposomes as systems to promote retinoids percutaneous absorption
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