Nano and Microtechnologies for the Delivery of Oligonucleotides with Gene Silencing Properties

Oligonucleotides (ONs) are synthetic fragments of nucleic acid designed to modulate the expression of target proteins. DNA-based ONs (antisense, antigene, aptamer or decoy) and more recently a new class of RNA-based ONs, the small interfering RNAs (siRNAs), have gained great attention for the treatment of different disease states, such as viral infections, inflammation, diabetes, and cancer. However, the development of therapeutic strategies based on ONs is hampered by their low bioavailability, poor intracellular uptake and rapid degradation in biological fluids. The use of a non-viral carrier can be a powerful tool to overcome these drawbacks. Lipid or polymer-based nanotechnologies can improve biological stability and cellular uptake of ONs, with possibility of tissue and/or cellular targeting. The use of polymeric devices can also produce a prolonged release of the ON, thus reducing the need of frequent administrations. This review summarizes advantages and issues related to the main non-viral vectors used for ON delivery

Retention behaviour of anti-emetic serotonin antagonists in reversed phase high performance liquid chromatography.

Granisetron, Ondansetron and Tropisetron, three 5-HT3 antagonists showing anti-emetic activity, were analysed by HPLC on lipophilic stationary phases. The addition of an amine or quaternary ammonium salt to the eluents was a powerful tool in the analysis of these basic substances. The influence on chromatographic parameters of pH, ionic strength and various counter-ions in the aqueous phase as well as of different organic modifiers is discussed. Some of the proposed experimental conditions allow a more strictly partition-based separation mechanism and can produce chromatographic parameters suitable for structure-activity studies. These experimental conditions are also suitable for analysis of the considered compounds in pharmaceutical dosage forms or in biological fluids

Interactions of nonsteroidal antiinflammatory drugs with phospholipids: comparison between octanol/buffer partition coefficients and chromatographic indexes on immobilized artificial membranes.

A set of seventeen nonsteroidal antiinflammatory drugs (NSAIDs), consisting of structurally unrelated carboxylic acids and piroxicam, was examined by high-performance liquid chromatography (HPLC) on an immobilized artificial membrane (IAM) column that is a solid-phase model of fluid membranes. The chromatographic capacity factors extrapolated to 100\% aqueous phase (log KWIAM) were compared with n-octanol/buffer lipophilicity parameters. The interactions with phospholipids were much better predicted from the intrinsic partition coefficient, log P, than from the apparent partition value, log D7.4, indicating that phospholipids can counteract the influence of electrically charged functions of analytes on lipophilic interactions. The log KWIAM and log P values for both NSAIDs and structurally unrelated neutral compounds result in unique scale if uniquely partition-based mechanisms take place. However, an electrostatic repulsion component was observed for the NSAIDs bearing the carboxylic function directly linked to the aromatic ring, and for ibuprofen. Hence, the IAM-derived scale is distinctive from the one obtained by lipophilic parameters. The IC50 values on cyclooxygenase 2 (COX-2) in intact cells determined by different authors have been successfully correlated with respective IAM parameters, whereas no correlation was found with COX-1 activity data. These results suggest that membrane affinity may represent an important prerequisite for the specific binding NSAIDs/COX-2

Chromatographic indexes on immobilized artificial membranes for local anesthetics: relationships with activity data on closed sodium channels.

PURPOSE: To elucidate the effectiveness of the different parameters for the prediction of biological activity, the n-octanol/buffer partition coefficients and theoretical calculated lipophilicity parameters of thirteen local anesthetic drugs (LAs), including two beta-blockers, were compared to the affinity values for phospholipids, calculated by a recent technique. METHODS: Interactions with phospholipids were measured by high performance liquid chromatography on a stationary phase made up of phospholipids, the so-called "Immobilized Artificial Membrane" (IAM). Reference lipophilicity parameters were measured by shake-flask method between n-octanol and buffer phases. RESULTS: Interactions with phospholipids were predicted from log P for all compounds except tocainide, which also showed additive polar extra-interactions. Moreover, when the retention on Immobilized Artificial Membrane (IAM) phase was mainly lipophilicity-based, a unique scale included the correlation between log kwIAM and log P values, for both LAs (bases) and the structurally unrelated (nonionizable and acidic) compounds previously studied. IAM interaction values for LAs were predictive of the partition measures on liposome membranes already reported in literature. The half-blocking doses for closed sodium channel, corrected for ionization at pH 7.4, were successfully correlated with the respective IAM values for eleven compounds while procaine and tetracaine, which are ester-linked compounds and have a p-amino group as well, gave more potent results than predicted by phospholipid interactions. CONCLUSIONS: The IAM chromatographic parameters were much more effective than reference lipophilicity values in describing partition on model membranes and in predicting pharmacological potency on closed sodium channels

Chromatographic indices determined on an immobilized artificial membrane (IAM) column as descriptors of lipophilic and polar interactions of 4-phenyldihydropyridine calcium channel blockers with biomembranes

A set of nine 4-phenyldihydropyridine (DHP) calcium-channel blockers including both ionizable and unionizable molecules has been examined. The chromatographic parameters log k' have been determined by HPLC on an immobilized artificial membrane (IAM) column which is a solid-phase model of fluid membranes. The influence of different percentages of organic modifier and ionic strength of the eluent on the chromatographic behaviour has been studied in order to identify the best experimental conditions modelling the in vivo interaction with phospholipids. As different ranking orders can occur under different experimental conditions, log k' values extrapolated to 100% aqueous phase (log kwIAM) have been determined. Moreover, n-octanol/buffer partition data at pH 7.4 and 12.5 (log D7.4 and log P) and chromatographic data on a hydrocarbon HPLC stationary phase (log kwODS) have been measured. Comparative studies between the experimental data, obtained for the different systems, have shown that the IAM-derived scale is distinct from the one obtained by 'conventional' lipophilic indices, because of the particular behaviour of the basic DHPs. Moreover, only IAM parameters are good descriptors of the strong interactions of the basic DHPs with biomembranes. In fact, the chromatography of neutral compounds is mainly lipophilicity dependent while a 'dual' mechanism, partition and ion-exchange, operates for basic analogues. In this case the lipophilic component is insensitive to the protonation of the basic function. Finally, receptor binding values from rat cortical brain preparations successfully correlate with log kwIAM. Hence, the biomembrane affinity of DHPs appears to be a critical factor for access to their receptor sit

Transferosomes and ethosomes for the trans-resveratrol permeation through the skin: a comparative study.

Introduction: The trans-resveratrol (t-res) is a non flavonoid polyphenol with promising properties for the treatment or prevention of different diseases. In particular, topical application of resveratrol could be advantageous in the prevention of skin cancer or in the treatment of inflammation-based diseases such as psoriasis. However, different studies demonstrated the importance of the formulation to enhance t-res delivery into or trough the skin. Nanocarriers, such as ethosomes and transferosomes, have been successfully used to deliver drugs with different characteristics into or through the skin. Purpose: The aim of the present work was to develop a nanocarrier-based formulations for skin delivery of t-res. Methods: Ethosomes or transferosomes containing t-res were prepared by a modified hand-shaking method followed by extrusion or sonication. All the formulations were characterised in terms of mean diameter, size distribution (I.P.), t-res loading, t-res stability upon encapsulation during storage at 4°C. The inhibition of reactive oxygen species (ROS) and lipids peroxidation in human keratinocyte (HaCaT) cell line stimulated with H2O2 for 24 h and then incubated with the t-res containing nanocarriers was investigated. Moreover, for all the formulations, ex vivo permeation studies on porcine skin was carried out by means of Franz diffusion cells. At appropriate intervals (0.5, 1, 2, 4, 6, 24 h), an aliquots of the receptor medium were withdrawn and the t-res concentration was determined by HPLC. Results: All the t-res containing carriers were characterised by a very high (between 70 to 100%) encapsulation efficiency, a limited t-res release at 4°C during the storage and stability of resveratrol in its trans form. Nanocarriers encapsulating t-res reduced, in a concentration-dependent manner, ROS production induced by H2O2, with the higher effect observed in the case of ethosomes. Permeation studies showed that only ethosomes were able to promote t-res permeation through porcine skin and this effect was affected by lipid composition of the carrier. Conclusions: In this work, transferosomes showed the highest encapsulation efficiency and the lowest t-res release. On the other hand, only ethosomes were able to promote t-res permeation through the skin