Viscoelasticity of Liposomal Dispersions.

Janus-faced viscoelastic gelling agents-possessing both elastic and viscous characteristics-provide materials with unique features including strengthening ability under stress and a liquid-like character with lower viscosities under relaxed conditions. The mentioned multifunctional character is manifested in several body fluids such as human tears, synovial liquids, skin tissues and mucins, endowing the fluids with a special physical resistance property that can be analyzed by dynamic oscillatory rheology. Therefore, during the development of pharmaceutical or cosmetical formulations-with the intention of mimicking the physiological conditions-rheological studies on viscoelasticity are strongly recommended and the selection of viscoelastic preparations is highlighted. In our study, we aimed to determine the viscoelasticity of various liposomal dispersions. We intended to evaluate the impact of lipid concentration, the presence of cholesterol or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and the gelling agents polyvinyl alcohol (PVA) and hydroxyethylcellulose (HEC) on the viscoelasticity of vesicular systems. Furthermore, the effect of two model drugs (phenyl salicylate and caffeine) on the viscoelastic behavior of liposomal systems was studied. Based on our measurements, the oscillation rheological properties of the liposomal formulations were influenced both by the composition and the lamellarity/size of the lipid vesicles.

Determination of the Main Phase Transition Temperature of Phospholipids by Oscillatory Rheology.

Knowledge of the physical and chemical properties of phospholipids, such as phase transition temperatures (Tc), is of great importance in order to reveal the functionalities of biological and artificial membranes. Our research group developed an oscillatory rheological method for the simple and rapid determination of phase transition temperatures (Tc). The phospholipids constructing the membranes undergo conformational changes at their Tc, which cause alterations of viscoelastic properties of the molecules. The oscillatory technique recommended by us proved to be appropriate to reveal the altered molecular properties of phospholipids as tracking the slightest changes in the viscoelasticity. Our study demonstrates the abrupt changes in rheological properties at Tc for the following phospholipids: 1,2-Dimyristoyl-sn-glycero-3-Phosphocholine (DMPC), 1,2-Dipalmitoyl-sn-glycero-3-Phosphatidylcholine (DPPC), and 1,2-Distearoyl-sn-glycero-3-Phosphocholine (DSPC), proving that the applied methodology is adequate for determining the Tc of phospholipids.

Rheological Considerations of Pharmaceutical Formulations: Focus on Viscoelasticity.

Controlling rheological properties offers the opportunity to gain insight into the physical characteristics, structure, stability and drug release rate of formulations. To better understand the physical properties of hydrogels, not only rotational but also oscillatory experiments should be performed. Viscoelastic properties, including elastic and viscous properties, are measured using oscillatory rheology. The gel strength and elasticity of hydrogels are of great importance for pharmaceutical development as the application of viscoelastic preparations has considerably expanded in recent decades. Viscosupplementation, ophthalmic surgery and tissue engineering are just a few examples from the wide range of possible applications of viscoelastic hydrogels. Hyaluronic acid, alginate, gellan gum, pectin and chitosan are remarkable representatives of gelling agents that attract great attention applied in biomedical fields. This review provides a brief summary of rheological properties, highlighting the viscoelasticity of hydrogels with great potential in biomedicine.

Antidotal efficacies of the cyanide antidote candidate dimethyl trisulfide alone and in combination with cobinamide derivatives.

Formulation optimization and antidotal combination therapy are the two important tools to enhance the antidotal protection of the cyanide (CN) antidote dimethyl trisulfide (DMTS). The focus of this study is to demonstrate how the formulation with polysorbate 80 (Poly80), an excipient used in pharmaceutical technology, and the combinations with other CN antidotes having different mechanisms of action enhance the antidotal efficacy of the unformulated (neat) DMTS. The LD50 for CN was determined by the statistical Dixon up-and-down method on mice. Antidotal efficacy was expressed as antidotal potency ratio (APR). CN was injected subcutaneously one minute prior to the antidotes' injection intramuscularly. The APR values of 1.17 (dose: 25 mg/kg bodyweight) and 1.45 (dose: 50 mg/kg bodyweight) of the neat DMTS were significantly enhanced by the Poly80 formulation at both investigated doses to 2.03 and 2.33, respectively. The combination partners for the Poly80 formulated DMTS (DMTS-Poly80; 25 and 50 mg/kg bodyweight) were 4-nitrocobinamide (4NCbi) (20 mg/kg bodyweight) and aquohydroxocobinamide (AHCbi; 50, 100, and 250 mg/kg bodyweight). When DMTS-Poly80 (25 and 50 mg/kg bodyweight; APR = 2.03 and 2.33, respectively) was combined with 4NCbi (20 mg/kg bodyweight; APR = 1.35), significant increase in the APR values were noted at both DMTS doses (APR = 2.38 and 3.12, respectively). AHCbi enhanced the APR of DMTS-Poly80 (100 mg/kg bodyweight; APR = 3.29) significantly only at the dose of 250 mg/kg bodyweight (APR = 5.86). These studies provided evidence for the importance of the formulation with Poly80 and the combinations with cobinamide derivatives with different mechanisms of action for DMTS as a CN antidote candidate.

Past, present and future of cyanide antagonism research: From the early remedies to the current therapies.

This paper reviews milestones in antidotal therapies for cyanide (CN) spanning early remedies, current antidotal systems and research towards next generation therapies. CN has been a part of plant defense mechanisms for millions of years. It became industrially important in the nineteenth century with the advent of CN assisted gold mining and the use of CN as a pest control agent. The biochemical basis of CN poisoning was actively studied and key mechanisms were understood as early as 1929. These fundamental studies led to a variety of antidotes, including indirect CN binders that generate methemoglobin, direct CN binders such as hydroxocobalamin, and sulfur donors that convert CN to the less toxic thiocyanate. Research on blood gases at the end of the twentieth century shed new light on the role of nitric oxide (NO) in the body. The discovery of NO's ability to compete with CN for enzymatic binding sites provided a previously missed explanation for the rapid efficacy of NO generating antidotes such as the nitrites. Presently used CN therapies include: methemoglobin/NO generators (e.g., sodium nitrite, amyl nitrite, and dimethyl aminophenol), sulfur donors (e.g., sodium thiosulfate and glutathione), and direct binding agents [(e.g., hydroxocobalamin and dicobalt salt of ethylenediaminetetraacetic acid (dicobalt edetate)]. A strong effort is being made to explore novel antidotal systems and to formulate them for rapid administration at the point of intoxication in mass casualty scenarios. New antidotes, formulations, and delivery systems are enhancing bioavailability and efficacy and hold promise for a new generation of improved CN countermeasures.

Ciprofloxacin encapsulation into giant unilamellar vesicles: membrane binding and release.

This study aimed at investigating some respects of binding and interaction between water-soluble drugs and liposomal carrier systems depending on their size and lamellarity. As model substance, ciprofloxacin hydrochloride (CPFX) was incorporated into giant unilamellar vesicles (GUVs) to study their CPFX encapsulation/binding capacity. To characterize molecular interactions of various CPFX microspecies with lipid bilayer, zeta potential and electron paramagnetic resonance (EPR) spectroscopy measurements were performed. The increase of the zeta potential at pH 5.4 but no change at pH 7.2 was interpreted in terms of the CPFX microspecies' distribution at the two pH values. EPR observations showed an increased fluidity because of CPFX binding to GUVs. We worked out and applied a three-compartment dialysis model to separately determine the rate of drug diffusion through the liposomal membrane. Equilibrium dialysis showed (a) different permeation of CPFX through the membranes of GUVs and multilamellar vesicles (MLVs), with characteristic half-lives of 54.4 and 18.1 h, respectively; and (b) increased retention of CPFX in case of GUVs with released amounts of 70% compared with about 97% in case of MLVs. Our results may provide further details for efficient design of liposomal formulations incorporating water-soluble drugs.

Liposomes for topical use: a physico-chemical comparison of vesicles prepared from egg or soy lecithin.

Developments in nanotechnology and in the formulation of liposomal systems provide the opportunity for cosmetic dermatology to design novel delivery systems. Determination of their physico-chemical parameters has importance when developing a nano-delivery system. The present study highlights some technological aspects/characteristics of liposomes formulated from egg or soy lecithins for topical use. Alterations in the pH, viscosity, surface tension, and microscopic/macroscopic appearance of these vesicular systems were investigated. The chemical composition of the two types of lecithin was checked by mass spectrometry. Caffeine, as a model molecule, was encapsulated into multilamellar vesicles prepared from the two types of lecithin: then zeta potential, membrane fluidity, and encapsulation efficiency were compared. According to our observations, samples prepared from the two lecithins altered the pH in opposite directions: egg lecithin increased it while soy lecithin decreased it with increased lipid concentration. Our EPR spectroscopic results showed that the binding of caffeine did not change the membrane fluidity in the temperature range of possible topical use (measured between 2 and 50 °C). Combining our results on encapsulation efficiency for caffeine (about 30% for both lecithins) with those on membrane fluidity data, we concluded that the interaction of caffeine with the liposomal membrane does not change the rotational motion of the lipid molecules close to the head group region. In conclusion, topical use of egg lecithin for liposomal formulations can be preferred if there are no differences in the physico-chemical properties due to the encapsulated drugs, because the physiological effects of egg lecithin vesicles on skin are significantly better than that of soy lecithin liposomes.

Optimization of liposomal encapsulation for ceftazidime for developing a potential eye drop formulation.

Ceftazidime is a broad spectrum third generation cephalosporin antibiotic which is effective mainly against Gram-negative bacteria such as Pseudomonas aeruginosa, Acinetobacter and Enterobacteriaceae, the pathogens which most often cause ophthalmological infections. Unlike other commonly used beta lactam antibiotics, ceftazidime is resistant to several types of beta lactamases (e.g., TEM, SHV and PSE-1). Because of these advantages, ceftazidime is used in the treatment of eye infections. However, ceftazidime undergoes rapid degradation in aqueous solutions therefore eye drops containing ceftazidime in aqueous solutions are not commercially manufactured. In the present study, liposomal encapsulations of ceftazidime with various lipid compositions, hydrating solutions and pH-values have been studied in order to optimize liposomal composition for a potential eye drop formulation.

A survey of the burden of allergic rhinitis in Hungary from a specialist's perspective.

BACKGROUND: The casual and severity distribution of allergic rhinitis (AR) in Hungary is unknown.The aim of this survey was to evaluate symptom perception, disease severity, concomitant asthma frequency and the impact of AR on everyday life activities in a cross-sectional, multicenter study in Hungary under the supervision of Hungarian Respiratory Society. METHODS: Data were recorded by 933 AR patients (65.93% women) and their treating specialists. The perceptions of patients regarding the symptoms (nasal, ocular and others) of AR and its severity, together with its impact on everyday life were assessed. Physicians recorded data regarding the diagnosis and severity of AR, and comorbidities. RESULTS: 52.5% of patients suffered from seasonal AR, 35.1% from perennial AR. A large proportion of patients had moderate to severe disease (MS-AR) (57.34%), persistent disease (98.0%) and concomitant asthma (53.32% in the mild, 57.52% in the MS-AR group). MS-AR was more frequent among women. Despite the treatment used, in MS-AR the proportions of patients reporting moderate to severe rhinorrhoea, nasal obstruction, ocular itching/redness, watering, itchy throat and sneezing were as high as 52.0%, 54.0%, 33.8%, 26.5%, 44.0% and 31.2%, respectively. Overall, there was a poor agreement between disease severity reported by patients and specialists. The adherence to oral antihistamines and intranasal corticosteroids was found to be between 50 and 65%; mostly depending on the dosage form. CONCLUSIONS: AR remains a significant health problem in Hungary because of the burden of symptoms, high rate of concomitant asthma and the significant proportion of MS-AR affecting general well being.

Natural oils and waxes: studies on stick bases.

The objective of the present article was to examine the role of origin and quantity of selected natural oils and waxes in the determination of the thermal properties and hardness of stick bases. The natural oils and waxes selected for the study were sunflower, castor, jojoba, and coconut oils. The selected waxes were yellow beeswax, candelilla wax, and carnauba wax. The hardness of the formulations is a critical parameter from the aspect of their application. Hardness was characterized by the measurement of compression strength along with the softening point, the drop point, and differential scanning calorimetry (DSC). It can be concluded that coconut oil, jojoba oil, and carnauba wax have the greatest influence on the thermal parameters of stick bases.

Nano-intercalated organophosphorus-hydrolyzing enzymes in organophosphorus antagonism.

A dendritic poly(2-alkyloxazoline)-based polymer was studied as a new carrier system for the organophosphorus-hydrolyzing recombinant enzymes, organophosphorus acid anhydrolase and organophosphorus hydrolase. Paraoxon (PO) and diisopropylfluorophosphate (DFP) were used as model organophosphorus compounds. Changes in plasma cholinesterase activity were monitored. The cholinesterase activity was proportional to the concentrations of DFP or PO. Plasma cholinesterase activity was higher in animals receiving enzyme and oxime before the organophosphates than in the oxime-only pretreated groups. These studies suggest that cholinesterase activity can serve as an indicator for the in vivo protection by the nano-intercalated organophosphorus acid anhydrolase or organophosphorus hydrolase against organophosphorus intoxications. These studies represent a practical application of polymeric nano-delivery systems as enzyme carriers in drug antidotal therapy.

Nanoencapsulated and microencapsulated enzymes in drug antidotal therapy.

A catalytic bioscavenger for the therapeutic and prophylactic defense against recognized chemical threat agents has been a long-standing objective of civilian and military research. Among the toxic agents, organophosphate molecules and cyanide have been widely studied. In order to overcome the limitations of traditional antidotal therapies, isolated, purified, recombinant enzymes with bacterial origin possessing fast catalytic activity were used in in vitro and in vivo experiments. However, the fast degradation, excretion and adverse immunologic reaction against enzymes limit their in vivo use. Development of biodegradable, nontoxic carrier systems, microparticles, and nanoparticles-offering advantageous pharmacokinetic parameters was suggested. Present work deals with the perspectives of carrier systems, such as resealed and annealed erythrocytes and sterically stabilized liposomes. Dendritic polymers and polymer-conjugated enzymes, being in the focus of extensive research efforts nowadays, are also discussed.

Optimization of liposomal lipid composition for a new, reactive sulfur donor, and in vivo efficacy studies on mice to antagonize cyanide intoxication.

Present studies have focused on a novel cyanide antidotal system, on the coencapsulation of a new sulfur donor DTO with rhodanese within sterically stabilized liposomes. The optimal lipid composition for coencapsulation of DTO with rhodanese is the combination of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, cholesterol, cationic lipid (DOTAP), and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] ammonium salt (with molar ratios of 82.7 : 9.2 : 3.0 : 5.1). With the optimized compositions, prophylactic and therapeutic in vivo efficacy studies were carried out in a mice model. When DTO was coencapsulated with rhodanese and thiosulfate the prophylactic antidotal protection was 4.9 × LD(50). Maximum antidotal protection against cyanide intoxication (15 × LD(50)) was achieved with coencapsulated rhodanese and DTO/thiosulfate in combination with sodium nitrite. When applied therapeutically, 100% survival rate (6/6) was achieved at 20 mg/kg cyanide doses with the encapsulated DTO-rhodanese-thiosulfate antidotal systems with and without sodium nitrite. These data are indicating that the appropriately formulated DTO is a promising sulfur donor for cyanide antagonism.

Patterns of erythropoiesis-stimulating agent use for chemotherapy-induced anemia in lung cancer: results of a retrospective Hungarian real-life clinical data analysis.

OBJECTIVE: Lung cancer carries a relatively high risk of chemotherapy-induced anemia, one of the most frequent hematological complications. Previous data show a lack of optimal anemia correction in patients with chemotherapy-induced anemia. This paper analyzes real-life data considering the prevalence and severity of chemotherapy-induced anemia, together with the frequency and efficacy of erythropoietin treatment of anemia in Hungarian lung cancer patients. RESEARCH DESIGN AND METHODS: Data of 482 patients with histological or cytological confirmed lung cancer receiving chemotherapy were collected retrospectively between 1 January and 31 December, 2008. In all, 83 (17%) of them developed chemotherapy-induced moderate to severe anemia (44.6% male, 55.4% female; mean age 70 ± 8.6 years; NSCLC 67.5%, small cell lung cancer 32.5%). RESULTS: More than 50% of the patients suffering from moderate to severe chemotherapy-induced anemia (hemoglobin below 10 g/dl) did not receive erythropoietin treatment. Chemotherapy had to be postponed due to anemia in 32.26% of the patients receiving erythropoietin supplementation, while this was seen in 41.94% of the group without erythropoietin treatment (p < 0.05). In patients not receiving erythropoietin, the severity of anemia increased, while erythropoietin treated patients maintained acceptable hemoglobin levels after the end of the chemotherapy. CONCLUSIONS: The data draws attention to the fact that nowadays chemotherapy-induced anemia is not treated according to current guidelines in many lung cancer cases in Hungary.

Nano-intercalated rhodanese in cyanide antagonism.

Present studies have focused on nano-intercalated rhodanese in combination with sulfur donors to prevent cyanide lethality in a prophylactic mice model for future development of an effective cyanide antidotal system. Our approach is based on the idea of converting cyanide to the less toxic thiocyanate before it reaches the target organs by utilizing sulfurtransferases (e.g., rhodanese) and sulfur donors in a close proximity by injecting them directly into the blood stream. The inorganic thiosulfate (TS) and the garlic component diallydisulfide (DADS) were compared as sulfur donors with the nano-intercalated rhodanese in vitro and in vivo. The in vivo and in vitro experiments showed that DADS is not a more efficient sulfur donor than TS. However, the utilization of external rhodanese significantly enhanced the in vivo efficacy of both sulfur donor-nitrite combinations, indicating the potential usefulness of enzyme nano-delivery systems in developing antidotal therapeutic agents.

[In vivo effect of food on absorption of fluoroquinolones]. / Fluorokinolonok in vivo étel-interakciós vizsgálatai.

Although food-drug interactions have been studied extensively in recent years, in the light of the complex nature of these interactions general guideline for clinical practice can not be given. Drug interactions with food (containing multivalent metal ions or protein) can have an influence on drug absorption with widely variety of mechanism, resulting in changes in both the rate and extent of bioavailability. Food-drug interaction can be important in the clinical practice. Studies of the interaction between food/juice and fluoroquinolones have produced conflicting results. A number of studies give evidence that fluoroquinolones forming slightly soluble complex with metal ions of food show reduced bioavailability. In the same time, concurrent ingestion of food/ juice with fluoroquinolones has been shown not to interfere with their absorption to a clinically significant degree.

Cisplatin-vinorelbine chemotherapy in non-small cell lung cancer is safe and well tolerated: results of a retrospective Hungarian clinical data analysis.

OBJECTIVE: The efficacy of cisplatin-vinorelbine chemotherapy (CT) in NSCLC is well established. In this retrospective data analysis, haematological safety and tolerability, furthermore the effects of cisplatin-vinorelbine combination on patients' quality of life (QoL) are examined by reviewing the clinical data of NSCLC patients in a retrospective manner. RESEARCH DESIGN/METHODS: All patients (n = 25) received the following regimen: cisplatin (80 mg/m(2) on day 1 by i.v. infusion) and vinorelbine (30 mg/m(2) on days 1 and 8 by i.v. infusion; 21-day cycles; patients received four cycles of CT). Haematological laboratory and QoL data on day 1 of all cycles were collected. Quality of life was assessed by reviewing the data of patients' charts considering physical limitation, fatigue, nausea, vomiting, diarrhoea, constipation, social activities, fever, appetite and weight loss. The absence of problems was scored as 0, moderate complaints as 1 and serious deterioration as 2. RESULTS: The QoL data showed no significant deterioration in the analysed symptoms of patients during the four cycles of cisplatin-vinorelbine CT (total QoL score was 3.0 +/- 1.4 points before treatment versus 3.6 +/- 0.5 on day 1 of the last cycle, p > 0.05). Haemoglobin values were 118.4 +/- 12.3 g/l before CT and 109.0 +/- 11.3 g/l on day 1 of last cycle of CT (p > 0.05). The mean number of platelets in the beginning and in the end was 256 +/- 123(*)10(12)/l and 217 +/- 119(*)10(12)/l, respectively (p < 0.05). White blood cell count was 8.36 +/- 3.21(*)10(9)/l, absolute granulocyte count 5.95 +/- 5.81(*)10(9)/l before the treatment, and these data were 4.50 +/- 1.96(*)10(9)/l and 2.15 +/- 1.21(*)10(9)/l, respectively, on day 1 of last cycle of CT (both p < 0.005). CONCLUSIONS: Cisplatin-vinorelbine CT is a safe and well-tolerated chemotherapeutic option of NSCLC.

Physicochemical characterization of stealth liposomes encapsulating an organophosphate hydrolyzing enzyme.

The present studies were focused on the preparation and characterization of stericaly stabilized liposomes (SLs) encapsulating a recombinant organophosphorus hydrolyzing phosphotriesterase (OPH) enzyme for the antagonism of organophosphorus intoxication. Earlier results indicate that the liposomal carrier system provides an enhanced protective effect against the organophosphorus molecule paraoxon, presenting a more effective therapy with less toxicity than the most commonly used antidotes. Physicochemical characterization of the liposomal OPH delivery system is essential in order to get information on its in vitro stability and in vivo fate. Osmolarity, pH, viscosity, and encapsulation efficiency of the SL preparation and the surface potential of the vesicles were determined. The membrane rigidity and the impact of OPH enzyme on it was studied by electron-paramagnetic resonance spectroscopy, using spin probes. The in vitro stability of the liposomal preparations, the vesicle size distribution, and its alteration during a 3-week storage were followed by dynamic light-scattering measurements. Further, the stability of encapsulated and nonencapsulated OPH was compared in puffer and plasma.

[Methods to increase the encapsulation efficiency for liposomal drugs]. / A bezárási hatásfok növelésének lehetoségei liposzómába zárt lomefloxacinnál.

Liposomes as drug delivery systems--in comparison to the traditional dosage forms--offer the advantage of the targeted drug delivery and as a consequence, reduction of the side effects. In case of fluoroquinolone antibiotics, such as lomefloxacin, the liposomal encapsulation of the active ingredient can result in an enhancement of its therapeutic efficacy against intracellular bacteria. The aim to improve the liposomal encapsulation efficiency of drugs--which is one of the main factors influencing the therapeutic effect of vesicular dosage forms--is one of the important challenges in the field of pharmaceutical technology. In our experiments we prepared lomefloxacin containing multilamellar vesicles from various lipids using different hydrating solutions. We intended to study the effect of lipid composition, cholesterol content and surface charge of liposomes on the encapsulation efficiency of lomefloxacin. Our results can contribute to the rational design of fluoroquinolone containing liposomal drugs.

Gels and liposomes in optimized ocular drug delivery: studies on ciprofloxacin formulations.

Ciprofloxacin (CPFX) containing therapeutic systems were developed using gel- and liposome-based formulations to minimize tear-driven dilution in the conjunctival sac, a long-pursued objective in ophthalmology. Physicochemical properties (pH, osmolarity, viscosity, expansivity, membrane fluidity and in vitro CPFX release rate) of the preparations were studied by the appropriate methods. For gel preparation, the bio-adhesive poly(vinyl alcohol) and polymethacrylic acid derivatives were applied in various concentrations. In our liposome-supported carrier systems, multilamellar vesicles from lecithin and alpha-L-dipalmithoyl-phosphatidylcholine provided the encapsulating agent. Electron paramagnetic resonance (EPR) spectroscopy was applied to study the molecular interactions in the ophthalmic formulations. The polymer hydrogels used in our preparations ensured a steady and prolonged active ingredient release. In addition, encapsulation of the CPFX into liposomes prolonged the in vitro release of the antibacterial agent depending on the lipid composition of the vesicles.