New vesicular ampicillin-loaded delivery systems for topical application: characterization, in vitro permeation experiments and antimicrobial activity

Nanostructured Non-Ionic Surfactant Carrier-Based Gel for Topical Delivery of Desoximetasone

Psoriasis is a chronic autoimmune skin disease impacting the population globally. Pharmaceutical products developed to combat this condition commonly used in clinical settings are IV bolus or oral drug delivery routes. There are some major challenges for effectively developing new dosage forms for topical use: API physicochemical nature, the severity of the disease state, and low bioavailability present challenges for pharmaceutical product developers. For non-severe cases of psoriasis, topical drug delivery systems may be preferred or used in conjunction with oral or parenteral therapy to address local symptoms. Elastic vesicular systems, termed “niosomes”, are promising drug delivery vehicles developed to achieve improved drug delivery into biological membranes. This study aimed to effectively incorporate a corticosteroid into the niosomes for improving the drug bioavailability of desoximetasone, used to treat skin conditions via topical delivery. Niosomes characterization measurements were drug content, pH, spreadability, specific gravity, content uniformity, rheology, and physicochemical properties. Formulations used a topical gelling agent, Carbomer 980 to test for in vitro skin permeation testing (IVPT) and accelerated stability studies. The developed niosomal test gel provided approximately 93.03 ± 0.23% to 101.84 ± 0.11% drug content with yield stresses ranging from 16.12 to 225.54 Pa. The permeated amount of desoximetasone from the niosomal gel after 24 h was 9.75 ± 0.44 µg/cm² compared to 24.22 ± 4.29 µg/cm² released from the reference gel tested. Furthermore, a drug retention study compared the test gel to a reference gel, demonstrating that the skin retained 30.88 ng/mg of desoximetasone while the reference product retained 26.01 ng/mg. A controlled drug release profile was obtained with a niosomal formulation containing desoximetasone for use in a topical gel formulation showing promise for potential use to treat skin diseases like psoriasis.

Chromatographic Methods for Quantitative Determination of Ampicillin, Dicloxacillin and Their Impurity 6-Aminopenicillanic Acid

Two accurate, precise and sensitive high-performance thin layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC) methods were developed for assay of ampicillin (AMP) and dicloxacillin (DX) in the presence of their impurity, 6-aminopenicillanic acid (APA). Method (A) is HPTLC method; using silica gel HPTLC F254 plates as a stationary phase with methanol: chloroform: acetic acid (1:9: 0.2, by volume) as a developing system. All the bands were scanned at 220 nm. Method (B) is reversed phase- HPLC which depended on isocratic elution using C18 column and mobile phase consisting of acetonitrile: water (60:40, v/v), pH adjusted to 4 with orthophosphoric acid, at a flow rate of 1 mL min-1 and ultraviolet detection at 240 nm. The proposed methods were validated as per ICH guidelines and their linearity was evident in the ranges of 0.5-2 μg band-1, 0.4-2 μg band-1 and 0.2-1.2 μg band-1 for method (A) and 5-40 μg mL-1, 5-40 μg mL-1 and 2-16 μg mL-1 for method (B) for AMP, DX and APA, respectively. The proposed methods were successfully used for assay of AMP and DX in pure form and in pharmaceutical formulation where no interference from the excipients was detected.

pH-sensitive niosomes: Effects on cytotoxicity and on inflammation and pain in murine models

pH-sensitive nonionic surfactant vesicles (niosomes) by polysorbate-20 (Tween-20) or polysorbate-20 derivatized by glycine (added as pH sensitive agent), were developed to deliver Ibuprofen (IBU) and Lidocaine (LID). For the physical-chemical characterization of vesicles (mean size, size distribution, zeta potential, vesicle morphology, bilayer properties and stability) dynamic light scattering (DLS), small angle X-ray scattering and fluorescence studies were performed. Potential cytotoxicity was evaluated on immortalized human keratinocyte cells (HaCaT) and on immortalized mouse fibroblasts Balb/3T3. In vivo antinociceptive activity (formalin test) and anti-inflammatory activity tests (paw edema induced by zymosan) in murine models were performed on drug-loaded niosomes. pH-sensitive niosomes were stable in the presence of 0 and 10% fetal bovine serum, non-cytotoxic and able to modify IBU or LID pharmacological activity in vivo. The synthesis of stimuli responsive surfactant, as an alternative to add pH-sensitive molecules to niosomes, could represent a promising delivery strategy for anesthetic and anti-inflammatory drugs.

Gel-embedded niosomes: preparation, characterization and release studies of a new system for topical drug delivery

In the present paper physical gels, prepared with two polysaccharides, Xanthan and Locust Bean Gum, and loaded with non-ionic surfactant vesicles, are described. The vesicles, composed by Tween20 and cholesterol or by Tween85 and Span20, were loaded with Monoammonium glycyrrhizinate for release experiments. Size and zeta (ζ)-potential of the vesicles were evaluated and the new systems were characterized by rheological and dynamo-mechanical measurements. For an appropriate comparison, a Carbopol gel and a commercial gel for topical applications were also tested. The new formulations showed mechanical properties comparable with those of the commercial product indicating their suitability for topical applications. In vitro release experiments showed that the polysaccharide network protects the integrity of the vesicles and leads to their slow release without disruption of the aggregated structures. Furthermore, being the vesicles composed of molecules possessing enhancing properties, the permeation of the loaded drugs topically delivered can be improved. Thus, the new systems combine the advantages of matrices for a modified release (polymeric component) and those of an easier permeability across the skin (vesicle components). Finally, shelf live experiments indicated that the tested gel/vesicle formulations were stable over 1 year with no need of preservatives.

Evaluation of anticancer activity of celastrol liposomes in prostate cancer cells

CONTEXT

Celastrol, a natural compound derived from the herb Tripterygium wilfordii, is known to have anticancer activity, but is not soluble in water.

OBJECTIVE

Formation of celastrol liposomes, to avoid the use of toxic solubilising agents.

MATERIALS AND METHODS

Two different formulations of PEGylated celastrol liposomes were fabricated. Liposomal characteristics and serum stability were determined using dynamic light scattering. Drug entrapment efficacy and drug release were measured spectrophotometrically. Cellular internalisation and anticancer activity was measured in prostate cancer cells.

RESULTS

Liposomal celastrol displayed efficient serum stability, cellular internalisation and anticancer activity, comparable to that of the free drug reconstituted in dimethyl sulfoxide.

DISCUSSION AND CONCLUSION

Liposomal celastrol can decrease the viability of prostate cancer cells, while eliminating the need for toxic solubilising agents.

Niosomes from 80s to present: the state of the art

Efficient and safe drug delivery has always been a challenge in medicine. The use of nanotechnology, such as the development of nanocarriers for drug delivery, has received great attention owing to the potential that nanocarriers can theoretically act as "magic bullets" and selectively target affected organs and cells while sparing normal tissues. During the last decades the formulation of surfactant vesicles, as a tool to improve drug delivery, brought an ever increasing interest among the scientists working in the area of drug delivery systems. Niosomes are self assembled vesicular nanocarriers obtained by hydration of synthetic surfactants and appropriate amounts of cholesterol or other amphiphilic molecules. Just like liposomes, niosomes can be unilamellar or multilamellar, are suitable as carriers of both hydrophilic and lipophilic drugs and are able to deliver drugs to the target site. Furthermore, niosomal vesicles, that are usually non-toxic, require less production costs and are stable over a longer period of time in different conditions, so overcoming some drawbacks of liposomes. The niosome properties are specifically dictated by size, shape, and surface chemistry which are able to modify the drug's intrinsic pharmacokinetics and eventual drug targeting to the areas of pathology. This up-to-date review deals with composition, preparation, characterization/evaluation, advantages, disadvantages and application of niosomes.

Lamellar self-assemblies of single-chain amphiphiles and sterols and their derived liposomes: distinct compositions and distinct properties

Typically, single-chain amphiphiles and sterols do not form fluid lamellar phases once hydrated individually. Most of the single-chain amphiphiles form actually micelles in aqueous environments, while sterols display a very limited solubility in water. However, under certain conditions, mixtures of single-chain amphiphiles and sterols lead to the formation of stable fluid bilayers. Over the past decade, several of these systems leading to fluid lamellar self-assemblies have been identified and this article reviews the current knowledge relative to these non-phospholipid bilayers made of single-chain amphiphiles and sterols. It presents an integrated view about the molecular features that are required for their stability, the properties they share, and the origin of these characteristics. It was also shown that these lamellar systems could lead to the formation of unilamellar vesicles, similar to phospholipid based liposomes. These vesicles display distinct properties that make them potentially appealing for technological applications; they display a limited permeability, they are stable, they are formed with molecules that are relatively chemically inert (and relatively cheap), and they can be readily functionalized. The features of these distinct liposomes and their technological applications are reviewed. Finally, the putative biological implications of these non-phospholipid fluid bilayers are also discussed.

Interaction of pH-sensitive non-phospholipid liposomes with cellular mimetic membranes

Surfactant nanocarriers have received considerable attention in the last several years as interesting alternative to classic liposomes. Different pH-sensitive vesicular colloidal carriers based on Tween 20 derivatives, obtained after functionalization of the head groups of the surfactant with natural, or simply modified, amino acids, were proposed as drug nanocarriers. Dynamic light scattering, Small Angle X-ray Scattering, Trasmission Electron Microscopy and fluorescence studies were used for the physico-chemical characterization of vesicles and mean size, size distribution, zeta potential, vesicle morphology and bilayer properties were evaluated. The pH-sensitivity and the stability of formulations, in absence and in presence of foetal bovine serum, were also evaluated. Moreover, the contact between surfactant vesicles and liposomes designed to model the cellular membrane was investigated by fluorescence studies to preliminary explore the potential interaction between vesicle and cell membranes. Experimental findings showed that physico-chemical and technological features of pH-sensitive vesicles were influenced by the composition of the carriers. Furthermore, proposed carriers are able to interact with mimetic cell membrane and it is reasonable to attribute the observed differences in interaction to the architectural/structural properties of Tween 20 derivatives. The findings reported in this investigation showed that a deep and extensive physico-chemical characterization of the carrier is a fundamental step, according to the evidence that the knowledge of nanocarrier properties is necessary to translate its potentiality to in vitro/in vivo applications.

Cavamax W7 composite ethosomal gel of clotrimazole for improved topical delivery: development and comparison with ethosomal gel

The present research work was aimed to formulate clotrimazole encapsulated Cavamax W7 composite ethosomes by injection method for improved delivery across epidermis. 3(2) factorial design was used to design nine formulations (F1-F9) and compared with ethosomal formulations (F10-F12). F9 with vesicle size of 202.8 ± 4.8 nm, highest zeta potential (-83.6 ± 0.96 mV) and %EE of 98.42 ± 0.15 was selected as optimized composite ethosome and F12 as reference ethosomal formulation. As revealed by transmission electron microscopy F9 vesicles were more condensed, uniformly spherical in shape than F12 vesicles. Vesicular stability studies indicated F9 to be more stable as compared to F12. Both F9 and F12 were incorporated in carbopol 934 gel base to get G1-G8 gel formulations and evaluated for in vitro skin permeability. Cavamax W7 composite ethosomal optimized gel (G5) showed higher in vitro percent cumulative drug permeation (88.53 ± 2.10%) in 8 h and steady state flux (J(ss)) of 3.39 ± 1.45 μg/cm(2)/min against the J(ss) of 1.57 ± 0.23 μg/cm(2)/min for ethosomal gel (G1) and 1.13 ± 0.06 μg/cm(2)/min for marketed formulation. The J(ss) flux of G5 was independent of amount of drug applied/unit area of skin. In vivo confocal laser scanning microscopic study of G5 depicted uniform and deeper penetration of rhodamine B (marker) in epidermis from Cavamax W7 composite ethosomal gel in comparison to G1. Finally, G5 demonstrated better (p < 0.05) antifungal activity against Candida albicans and Aspergillus niger than G1 thus, signifying that Cavamax W7 composite ethosomes present a superior stable and efficacious vesicular system than ethosomal formulation for topical delivery of clotrimazole.

Preparation and characterization of 5-fluorouracil pH-sensitive niosome and its tumor-targeted evaluation: in vitro and in vivo

The purpose of this study was to investigate preparation, characterization and tumor-targeted effect of pH-sensitive niosomes, composed of a nonionic surfactant mixed with cholesteryl hemisuccinate (CHEMS), a derivative of cholesterol (CHOL), as a pH-sensitive molecule. CHEMS was synthesized with CHOL and succinic acid, the structure of which was analyzed by Mass spectrometry (MS) and ¹H Nuclear magnetic resonance (¹H NMR) spectrum. Niosomes were prepared via film hydration-probe ultrasound method. Both normal niosomes and pH-sensitive niosomes showed spherical morphology under transmission electron microscope (TEM) with a average particle sizes of 172 ± 6.2 nm and 153 ± 4.7 nm, respectively. The thermotropic behavior, structure changes and interaction of 5-fluorouracil (5-Fu) with other materials were characterized by differential scanning calorimetry (DSC), and the disappearance of the melting peak of drug revealed the fact that drug was encapsulated in niosomes. Bulk-equilibrium reverse-dialysis method was chosen to investigate the behavior of drug release from normal niosomes and pH-sensitive niosomes in different pH medium, and the results showed that the noisome containing CHEMS had a pH-sensitive property. Tumor-targeted effect was proved by the fact that pH-sensitive niosomes showed a remarkable high concentration in tumor site of the mice transplanted with tumor cell.

Effect of cholesterol on the formation and hydration behavior of solid-supported niosomal membranes

The effect of cholesterol on the formation and hydration behavior of solid-supported polysorbate 20 (Tween 20)/cholesterol self-assemblies was investigated by means of in situ energy-dispersive X-ray diffraction in a wide range of relative humidity (0.4 < RH < 1). At low hydration, Tween 20 and cholesterol were found to demix, with the latter molecules forming crystallites with a pseudobilayer structure (d approximately = 34 A). Water adsorption promoted the progressive solubilization of cholesterol crystallites. When in the presence of enough cholesterol, the formation of niosomal bilayer membranes rich in Tween 20 occurred (RH approximately = 0.985). Upon further hydration, two distinct regimes associated with remarkable changes in the niosomal membrane structure were identified. In the first regime (0.985 < RH < 0.988), the swelling of the lamellar d spacing was due to the enlargement of the membrane thickness. In the second regime, the structure of Tween 20/cholesterol membranes was quite insensitive to hydration, and the thickness of the intermembrane water layer increased substantially. Remarkably, the curve of the calculated number of waters per surfactant molecule showed a distinct break at RH approximately 0.988, suggesting that the observed structural change in niosomal membranes was most likely due to the completion of the filling of the Tween 20 hydration shell. At full hydration, niosomal membranes exhibited the same lamellar d spacing of niosomes vesicles in aqueous solution. The process completely reversed upon dehydration.

Development of naftifine hydrochloride alcohol-free niosome gel

Marketed topical gels of the antifungal drug naftifine hydrochloride contain 50% alcohol as cosolvent. Repeated exposure to alcohol could be detrimental to skin. The aim of this study is to develop an alcohol-free niosome gel containing 1% naftifine hydrochloride. Niosomes were prepared and formulation variables were optimized to achieve maximum entrapment coupled with stability. Maximum drug entrapment and niosome stability entailed imparting a negative charge to the vesicles where entrapment efficiency reached 50%. Niosomes were incorporated into a hydroxyethylcellulose gel. The final gel contained a total drug concentration of 1% (wt/wt) half of which was entrapped in the niosomes. The results suggest the potential usefulness of the niosome gel.

pH-sensitive non-phospholipid vesicle and macrophage-like cells: binding, uptake and endocytotic pathway

Phospholipid and non-phospholipid vesicles are extensively studied as drug delivery systems to modify pharmacokinetics of drugs and to improve their action in target cells. It is believed that the major barrier to efficient drug delivery is entrapment of drugs in the endosomal compartment, since this eventually leads to its degradation in lysosomes. For these reasons, the knowledge of internalization pathway plays a fundamental role in optimizing drug targeting. The aim of this work is to characterize pH-sensitive Tween 20 vesicles, their interaction with macrophage-like cells and their comparison with pH-sensitive liposomes. The effect of different amounts of cholesteryl hemissucinate on surfactant vesicle formation and pH-sensitivity was studied. To evaluate the initial mode of internalization in Raw 264.7 and the intracellular fate of neutral and pH-sensitive formulations, flow cytometry in presence and in absence of selected inhibitors and fluorescence microscopy in absence and presence of specific fluorescent endocytotic markers were used. The obtained results showed that the surfactant vesicle pH-sensitivity was about two or three fold higher than that obtained with pH-sensitive liposomes in the presence of serum in vitro. The uptake mechanism of surfactant vesicles, after incubation with macrophage-like cells, is comparable to that of liposomes (clathrin-mediated endocytosis).

Formulation development and in vitro and in vivo evaluation of membrane-moderated transdermal systems of ampicillin sodium in ethanol: pH 4.7 buffer solvent system

The objective of the present study was to develop membrane-moderated transdermal systems of ampicillin sodium and to evaluate them with respect to various in vitro and in vivo parameters. The membrane-type transdermal systems were prepared using a drug with various antinucleant polymers-hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), cellulose acetate phthalate, chitosan, sodium alginate (SA), and sodium carboxymethylcellulose-in an ethanol: pH 4.7 buffer volatile system by the solvent evaporation technique with HPMC as the rate-controlling membrane for all the systems. The swelling properties of the polymers were studied, and drug-polymer interaction studies were performed. The patches were subjected to various physicochemical studies, in vitro release studies, permeation studies, and skin irritation studies. The best patch among the formulations was selected for further in vivo studies. Compared to the other patches, SA exhibited the highest moisture content at 16%; a 21% moisture uptake was found with MC. The release and permeation of the drug from the SA patch was found to be the maximum. The in vivo study of the SA patch exhibited a peak plasma concentration C(max) of 126 microg/mL at T(max) 4 hours. Hence, it can be concluded that hydrophilic ampicillin sodium can be developed as a transdermal delivery system with SA that is an alternative to intravenous administration and has minimal adverse effects.

Designing novel pH-sensitive non-phospholipid vesicle: characterization and cell interaction

In this work, we report the preparation, the characterization and interaction with cells of novel pH-sensitive non-phospholipid vesicle formulations, from a non-ionic surfactant mixed with cholesterol (CHOL) and his derivative cholesteryl hemisuccinate (CHEMS), as pH-sensitive molecule. This molecule, can destabilize the vesicle lipid bilayer when exposed to an acidic environment, with a subsequent release of vesicular content, enhancing the cytoplasmatic delivery of drugs to target cells. Vesicles were characterized by static and dynamic light scattering, in order to evaluate their dimensions, bilayer thickness and vesicle stability. Membrane permeability changes were determined by the release of entrapped hydroxypyrene-1,3,6-trisulfonic acid (HPTS). Also diphenylhesatriene (DPH) fluorescence anisotropy and zeta potential measurements were used to evidence the pH sensitivity. Furthermore vesicles were characterized by means of electronic microscopy after freeze-fracture. The interaction of non-lipid vesicles containing different fluorescent dyes with Raw 264.7, mouse monocite macrophage, were analyzed by flow cytometric analysis. The obtained results indicate that the pH-sensitive vesicular structures show good plasma stability and relevant pH-sensitivity. Moreover this formulation was able to interact with target membranes (i.e. plasma or endosomal membrane) and to release the encapsulated material into the cytoplasm.

In vitro evaluation ofin situ gels as short term vitreous substitutes

Dysfunction of the vitreous humor, present in the posterior cavity of the eye, leads to its detachment from the retina and vision loss. In this study, biopolymers were evaluated as in situ gels for short term vitreous substitution. Biophysical characterization revealed that the viscosity of the vitreous was >4000 cP at a shear rate of 0.15/s and it formed a gel with elastic modulus G' greater than the viscous modulus G''. Biopolymers of gellan and hyaluronic acid (8:2 w/w, 1% concentration) were low viscosity liquids at 37 degrees C and gelation was triggered both by the addition of 0.18 mM CaCl(2) as well as ocular temperature, thus making them feasible as in situ gels. Gelation was confirmed by viscoelastic moduli where G' was greater than G'', similar to the vitreous and unlike that of silicone oil, a common vitreous substitute. The gels had a viscosity >5000 cP at a shear rate of 0.512/s, excellent light transmittance and absence of syneresis. Contact angle studies with water and simulated ocular fluids showed that gellan hyaluronic acid gels had similar wetting properties to that of vitreous with contact angles of 27 degrees +/- 1 degrees , 36.7 degrees +/- 1.6 degrees , and 33.7 degrees +/- 0.5 degrees for water, simulated tear fluid, and simulated aqueous humor, respectively. The results of this study suggest that biopolymers of gellan and hylauronic acid are suitable as in situ gels, have biophysical properties similar to that of the vitreous, and may be promising as alternatives to silicone oil as short-term vitreous substitutes.