Simple and scalable method for peptide inhalable powder production

The aim of this work was to produce capreomycin dry powder and capreomycin loaded PLGA microparticles intended for tuberculosis inhalation therapy, using simple and scalable methods. Capreomycin physico-chemical characteristics have been modified by hydrophobic ion pairing with oleate. The powder suspension was processed by high pressure homogenization and spray-dried. Spray-drying was also used to prepare capreomycin oleate (CO) loaded PLGA microparticles. CO powder was suspended in the organic phase containing PLGA and the suspension was spray-dried. Particle dimensions were determined using photon correlation spectroscopy and Accusizer C770. Morphology was investigated by scanning electron microscopy (SEM) and capreomycin content by spectrophotometry. Capreomycin properties were modified to increase polymeric microparticle content and obtain respirable CO powder. High pressure homogenization allowed to reduce CO particle dimensions obtaining a population in the micrometric (6.18 μm) and one in the nanometric (～317 nm) range. SEM pictures showed not perfectly spherical particles with a wrinkled surface, generally suitable for inhalation. PLGA particles were characterized by a high encapsulation efficiency (about 90%) and dimensions (～6.69 μm) suitable for inhalation. Concluding, two different formulations were successfully developed for capreomycin pulmonary delivery. The hydrophobic ion pair strategy led to a noticeable drug content increase.     

Synthesis and In Vitro Release of Adriamycin from Star-Shaped Poly(Lactide-co-Glycolide) Nano- and Microparticles

The star-shaped poly(lactide-co-glycolide (PLGA)–β-cyclodextrin (PLGA–β-CD) copolymer was synthesized by reacting L-lactide, glycolide, and β-cyclodextrin in the presence of stannous octoate as a catalyst. The structure of PLGA–β-CD copolymer was confirmed with ¹H-NMR, ¹³C-NMR, and FT-IR spectra. Adriamycin (ADR), which is an antitumor antibiotic, was encapsulated within micro- and nanoparticles made of PLGA–β-CD with a modified double emulsion method. Relatively low amount of β-CD and catalyst were used in order to obtain high molecular weight polymers. Differential scanning calorimetry (DSC) was used to determine the thermal properties of star-shaped copolymers. The reduction of interactions between the starshaped polyester molecules is due to their branched structure lowered T_g and T_m compared to linear PLGA copolymers. Effects of the experimental parameters, such as copolymer composition, ADR concentration, copolymer concentration, and poly(vinyl alcohol) concentration, on particular size and encapsulation efficiency were investigated. An increase in the internal aqueous phase volume led to a decrease in particles average size. A decrease in the polymer concentration resulted in increasing the particle average size from 135.5 to 325.6 nm. The high entrapment efficiency (EE) (about 65%) was obtained for 220 μm particles. All of the release profiles indicated a close relationship between each formulation variable and the amount of ADR released.     

Intracellular oxidative stress and cadmium ions release induce cytotoxicity of unmodified cadmium sulfide quantum dots

ObjectiveTo fully understand the cytotoxicity of after-degradation QDs, we synthesized CdS QDs and investigated its toxicity mechanism.MethodsBiomimetic method was proposed to synthesize cadmium sulfide (CdS) QDs. Thereafter MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay was conducted to evaluate their cytotoxicity. To investigate the toxicity mechanism, we subsequently conducted intracellular reactive oxygen species (ROS) measurement with DCFH-DA, glutathione (GSH) measurement with DTNB, and cellular cadmium assay using atomic absorption spectrometer. Microsized CdS were simultaneously tested as a comparison.ResultsMTT assay results indicated that CdS QDs are more toxic than microsized CdS especially at concentrations below 40 μg/ml. While microsized CdS did not trigger ROS elevation, CdS QDs increase ROS by 20–30% over control levels. However, they both deplete cellular GSH significantly at the medium concentration of 20 μg/ml. In the presence of NAC, cells are partially protected from CdS QDs, but not from microsized particles. Additionally, nearly 20% of cadmium was released from CdS nanoparticles within 24 h, which also accounts for QDs’ toxicity.ConclusionIntracellular ROS production, GSH depletion, and cadmium ions (Cd²⁺) release are possible mechanisms for CdS QDs’ cytotoxicity. We also suggested that with QD concentration increasing, the principal toxicity mechanism changes from intracellular oxidative stress to Cd²⁺ release.     

Enhanced Oral Bioavailability of Paclitaxel Formulated in Vitamin E-TPGS Emulsified Nanoparticles of Biodegradable Polymers: In Vitro and In Vivo Studies

This work evaluates the effects of paclitaxel loaded polymeric nanoparticles (NPs) composed of poly(D,L-lactic-co-glycolic acid) (PLGA) with vitamin E TPGS as emulsifier for oral chemotherapy. NPs prepared by a modified solvent extraction/evaporation technique were observed in spherical shape of 200-300 nm diameter with a high drug encapsulation efficiency (EE) of 80.9%. The TPGS-emulsified PLGA NPs formulation of paclitaxel was found of great advantages over that of Taxol®. The in vitro viability experiment showed that the NP formulation could be 1.28,1.38,1.12 times more effective than Taxol® after 24, 48, 72 h incubation with MCF-7 human breast cancer cell line at 2.5 μg/mL paclitaxel concentration. In vivo evaluation confirmed the advantages of the TPGS-emulsified PLGA NP formulation versus Taxol® in promoting oral bioavailability of paclitaxel. Such a NP formulation achieved more than 10 times higher oral bioavailability than Taxol®, which resulted 9.74-fold higher therapeutic effect and 12.56-fold longer sustainable therapeutic time than Taxol®. The present proof-of-concept experimental data proved that the formulation of vitamin E TPGS emulsified PLGA NPs is a promising approach for paclitaxel oral administration. Oral chemotherapy by NPs formulation is feasible. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:3552-3560, 2010     

In vitro mutagenicity and blood compatibility of paclitaxel and curcumin in poly (dl-lactide-co-glicolide) films

Curcumin is considered to be a potential component for drug-eluting stents due to its anti-inflammatory properties. In this study we compared the mutagenicity and blood compatibility of curcumin to first generation drug eluting stent components: paclitaxel and sirolimus. The Ames test was used to assess mutagenicity. Blood compatibility was tested by measuring platelet activation and fibrinogen adsorption on poly (dl-lactide-co-glycolide, PLGA) films. We discovered that there was no significant increase in the number of revertants/plate following treatment with curcumin (up to 0.5 mg/plate) or sirolimus (up to 0.5 μg/plate). However, a significant induction in the frequency of bacterial his⁺ revertant colonies by paclitaxel at concentrations of 0.02, 0.05, 0.1, 0.2 and 0.5 μg/plate was observed. We also discovered a significant reduction in platelet activation by PLGA films containing 30% and 50% by weight curcumin. A similar reduction in platelet activation was also observed for PLGA films containing 1% by weight paclitaxel. In addition, we observed an increase of fibrinogen adsorption to PLGA-films containing curcumin. This would compromise the potential use of curcumin as a component of drug-eluting stents. Moreover, our data challenges the current view that paclitaxel does not significantly induce mutagenesis.     

Enhanced cellular association of paclitaxel delivered in chitosan-PLGA particles

We have previously demonstrated that the cellular association, cytotoxicity, and in vivo anti-tumor efficacy of paclitaxel are significantly greater when delivered in PLGA microparticles compared to nanoparticles. The purpose of this research is to test the hypothesis that mucoadhesive chitosan promotes adhesion of PLGA particles to mucus on the tumor epithelium, resulting in enhanced cellular association and cytotoxicity of paclitaxel. PLGA particles containing paclitaxel or Bodipy(?) were prepared and chitosan was either adsorbed or chemically conjugated to the particle surface. The cellular association and cytotoxicity of paclitaxel in 4T1 cells was determined. A 4-10 fold increase in cellular association of paclitaxel was observed when chitosan was adsorbed or conjugated to the PLGA particles. Chitosan-conjugated PLGA microparticles were most cytotoxic with an IC(50) value of 0.77 μM. Confocal microscopy demonstrated that chitosan-PLGA microparticles adhered to the surface of 4T1 cells. Pretreatment of either 4T1 cells or chitosan-PLGA particles with mucin resulted in significant increase in cellular association of paclitaxel. A linear correlation was established between theoretical amount of chitosan used and experimentally determined amount of chitosan adsorbed or conjugated to PLGA nanoparticles. In conclusion, cellular association and cytotoxicity of paclitaxel was significantly enhanced when delivered in chitosan-PLGA particles.     

Superparamagnetic iron oxide nanoparticles (SPIONs)-loaded Trojan microparticles for targeted aerosol delivery to the lung

Targeted aerosol delivery to specific regions of the lung may improve therapeutic efficiency and minimise unwanted side effects. Targeted delivery could potentially be achieved with porous microparticles loaded with superparamagnetic iron oxide nanoparticles (SPIONs)—in combination with a target-directed magnetic gradient field. The aim of this study was to formulate and evaluate the aerodynamic properties of SPIONs-loaded Trojan microparticles after delivery from a dry powder inhaler. Microparticles made of SPIONs, PEG and hydroxypropyl-β-cyclodextrin (HPβCD) were formulated by spray drying and characterised by various physicochemical methods. Aerodynamic properties were evaluated using a next generation cascade impactor (NGI), with or without a magnet positioned at stage 2. Mixing appropriate proportions of SPIONs, PEG and HPβCD allowed Trojan microparticle to be formulated. These particles had a median geometric diameter of 2.8 ± 0.3 μm and were shown to be sensitive to the magnetic field induced by a magnet having a maximum energy product of 413.8 kJ/m³. However, these particles, characterised by a mass median aerodynamic diameter (MMAD) of 10.2 ± 2.0 μm, were considered to be not inhalable. The poor aerodynamic properties resulted from aggregation of the particles. The addition of (NH₄)₂CO₃ and magnesium stearate (MgST) to the formulation improved the aerodynamic properties of the Trojan particles and resulted in a MMAD of 2.2 ± 0.8 μm. In the presence of a magnetic field on stage 2 of the NGI, the amount of particles deposited at this stage increased 4-fold from 4.8 ± 0.7% to 19.5 ± 3.3%. These Trojan particles appeared highly sensitive to the magnetic field and their deposition on most of the stages of the NGI was changed in the presence compared to the absence of the magnet. If loaded with a pharmaceutical active ingredient, these particles may be useful for treating localised lung disease such as cancer nodules or bacterial infectious foci.     

Mucoadhesive microparticles as potential carriers in inhalation delivery of doxycycline hyclate: a comparative study

The present work compares and evaluates the suitability of different polymer-based microparticles for inhalation delivery of doxycycline hyclate. Mucoadhesive polymers, such as sodium carboxymethyl cellulose, sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, starch, and carbopol were selected as carriers for inhalation delivery. Microparticles were prepared by spray drying and evaluated in terms of yield, moisture content, morphology, tapped density, encapsulation efficiency, in vitro mucoadhesion, thermal properties and in vitro aerosolization performance. Additionally, the cytotoxicity of the microparticles on H1299 human alveolar cell line was examined. Smooth spherical to collapsed doughnut shaped particles were formed. They exhibited tap densities of 0.202–0.502 g/cm³ and mass median aerodynamic diameter of 3.74–6.54 μm. Mucoadhesion was highest in case of carbopol-based microparticles. Drug release from these microparticles exhibited biphasic Fickian type of diffusion. Only at the highest concentration of microparticles (1 mg/mL) less than 90% cell viability was seen in DX loaded sodium alginate microparticles (DXSA, 87.2%), starch microparticles (DXST, 85.1%) and carbopol microparticles (DXCP, 82.7%) preparations after 48 h of exposure to alveolar cells. The results clearly indicate that sodium carboxymethyl cellulose-based microparticles may serve as an ideal carrier for inhalation delivery of doxycycline hyclate.     

Zinc oxide nanoparticle disruption of store-operated calcium entry in a muscarinic receptor signaling pathway

The influences of ZnO nanoparticles on cellular responses to activation of muscarinic receptors were studied in Chinese hamster ovary cells expressing the human M3 muscarinic acetylcholine receptor. ZnO particles (20 nm) induced cytotoxicity in a time and concentration-dependent manner: following a 24 h exposure, toxicity was minimal at concentrations below 20 μg/ml but virtually complete at concentrations above 28 μg/ml. ZnO particles did not affect antagonist binding to M3 receptors or allosteric ligand effects, but increased agonist binding affinity while eliminating guanine nucleotide sensitivity. At a noncytotoxic concentration (10 μg/ml), ZnO increased resting [Ca²⁺]_i from 40 to 130 nM without compromising calcium homeostatic mechanisms. ZnO particles had minimal effects on IP3- or thapsigargin-mediated release of intracellular calcium from the endoplasmic reticulum, but strongly inhibited store-operated calcium entry (capacitive calcium entry). The latter effect was seen as (1) a decrease in the plateau phase of the response and (2) a decrease in Ca²⁺ entry upon introduction of calcium to the extracellular medium following thapsigargin-induced depletion of calcium from the endoplasmic reticulum (EC50’s ≈ 2 μg/ml). Thus, ZnO nanoparticles interfere with two specific aspects of the M3 signaling pathway, agonist binding and store-operated calcium entry.     

Antitumoral activity of camptothecin-loaded nanoparticles in 9L rat glioma model

Camptothecin (CPT), a plant alkaloid, is a potent anticancer drug in cell culture studies but it is clinically inactive due to rapid hydrolysis under physiological conditions. The drug exists in two forms depending on the pH value, an active lactone form at pH below 5 and an inactive carboxylate form at basic pH and this is a reversible reaction. In this study, nanoparticulate delivery systems were developed with either amphiphilic cyclodextrins, poly(lactide-co-glycolide) or poly-?-caprolactone in order to maintain the active lactone form and prevent the drug from hydrolysis. All nanoparticles were prepared with nanoprecipitation technique. Mean particle sizes were 130–280 nm and surface charges were negative. The encapsulation efficiency was significantly higher for amphiphilic cyclodextrin nanoparticles when compared to polymeric nanoparticles. Nanoparticle formulations based on cyclodextrins showed a controlled release profile extended up to 12 days. 6-O-Capro-β-cyclodextrin (1.44 μg/60 μL CPT) and concentrated 6-O-Capro-β-cyclodextrin (2.88 μg/60 μL CPT) nanoparticles significantly modified the growth or lethality of the 9L gliomas, since the median survival time was 26 days for the untreated group and between 27 and 33 days for amphiphilic cyclodextrin nanoparticle groups. These results indicate that, CPT-loaded amphiphilic cyclodextrin nanoparticles may provide a promising carrier system for the effective delivery of CPT in comparison to polymeric analogues.     

Reduction in burst release of PLGA microparticles by incorporation into cubic phase-forming systems

A high initial burst release of an phosphorothioate oligonucleotide drug from poly(lactide-co-glycolide) (PLGA) microparticles prepared by the w/o/w solvent extraction/evaporation was reduced by incorporating the microparticles into the following glycerol monooleate (GMO) formulations: 1) pure molten GMO, 2) preformed cubic phase (GMO + water) or 3) low viscosity in situ cubic phase-forming formulations (GMO + water + cosolvent). The in situ cubic phase-forming formulations had a low viscosity in contrast to the first two formulations resulting in good dispersability of the microparticles and good syringability/injectability. Upon contact with an aqueous phase, a highly viscous cubic phase formed immediately entrapping the microparticles. A low initial burst and a continuous extended release over several weeks was obtained with all investigated formulations. The drug release profile could be well controlled by the cosolvent composition with the in situ systems.     

Spray-Dried Chitosan Microparticles for Cellular Delivery of an Antigenic Protein: Physico-chemical Properties and Cellular Uptake by Dendritic Cells and Macrophages

Purpose

Spray-dried chitosan microparticles for cellular delivery of antigen to dendritic cells (DC) and macrophages (M?) were investigated.

Methods

Chitosan microparticles were prepared by spray drying. For comparison, poly(lactic-co-glycolic acid) (PLGA) and poly(α-butyl cyanoacrylate) (BCA) micro-/nanoparticles were generated. Bovine serum albumin (BSA) was used as a model antigen. The particles were characterized in terms of size, morphology, surface charge, surface composition, protein content, entrapment efficiency, in vitro release, and protein integrity. Additionally, they were subject to cell viability and cellular uptake study with DC and M?.

Results

Size of chitosan, PLGA, and BCA micro-/nanoparticles ranged between 3.11–7.18, 0.94–6.26, and 0.30–6.34 μm, respectively. Particle morphology and in vitro protein release varied, depending on polymer type, particle composition and preparation process parameters. Chitosan microparticles were cationic, while PLGA microparticles were neutral. BCA micro-/nanoparticles were either anionic or cationic, according to polymerization pH. Protein content and entrapment efficiency of chitosan and PLGA microparticles were relatively consistent. Only integrity and conformational structure of protein encapsulated in chitosan microparticles were completely retained. Chitosan and PLGA microparticles were non-toxic to DC and M?, but the former were internalized more efficiently.

Conclusions

Spray-dried chitosan microparticles delivered the antigen efficiently to DC and M?.     

A-1048400 is a novel, orally active, state-dependent neuronal calcium channel blocker that produces dose-dependent antinociception without altering hemodynamic function in rats

Blockade of voltage-gated Ca²⁺ channels on sensory nerves attenuates neurotransmitter release and membrane hyperexcitability associated with chronic pain states. Identification of small molecule Ca²⁺ channel blockers that produce significant antinociception in the absence of deleterious hemodynamic effects has been challenging. In this report, two novel structurally related compounds, A-686085 and A-1048400, were identified that potently block N-type (IC₅₀ = 0.8 μM and 1.4 μM, respectively) and T-type (IC₅₀ = 4.6 μM and 1.2 μM, respectively) Ca²⁺ channels in FLIPR based Ca²⁺ flux assays. A-686085 also potently blocked L-type Ca²⁺ channels (EC₅₀ = 0.6 μM), however, A-1048400 was much less active in blocking this channel (EC₅₀ = 28 μM). Both compounds dose-dependently reversed tactile allodynia in a model of capsaicin-induced secondary hypersensitivity with similar potencies (EC₅₀ = 300–365 ng/ml). However, A-686085 produced dose-related decreases in mean arterial pressure at antinociceptive plasma concentrations in the rat, while A-1048400 did not significantly alter hemodynamic function at supra-efficacious plasma concentrations. Electrophysiological studies demonstrated that A-1048400 blocks native N- and T-type Ca²⁺ currents in rat dorsal root ganglion neurons (IC₅₀ = 3.0 μM and 1.6 μM, respectively) in a voltage-dependent fashion. In other experimental pain models, A-1048400 dose-dependently attenuated nociceptive, neuropathic and inflammatory pain at doses that did not alter psychomotor or hemodynamic function. The identification of A-1048400 provides further evidence that voltage-dependent inhibition of neuronal Ca²⁺ channels coupled with pharmacological selectivity vs. L-type Ca²⁺ channels can provide robust antinociception in the absence of deleterious effects on hemodynamic or psychomotor function.     

Release of Prednisolone and Inulin from a New Calcium-Alginate Chitosan-Coated Matrix System for Colonic Delivery

Putative colonic release formulations of calcium (Ca)-alginate coated with chitosan containing two different actives, prednisolone and inulin, were prepared in three different sizes, beads (D₅₀ = 2104 μm) and microparticles (D₅₀ = 354 and 136 μm). The formulations were tested in standard phosphate buffer and biorelevant Krebs bicarbonate buffer at pH 7.4, and were further evaluated in the presence of the bacterium E. coli. Product yield and encapsulation were higher with prednisolone than with inulin. In Krebs bicarbonate buffer, a clear relationship between particle size and prednisolone release was observed. In contrast, release of inulin was independent of the particle size. In phosphate buffer, the particles eroded quickly, whereas in Krebs buffer, the particles swelled slowly. The difference in behavior can be attributed to the formation of calcium phosphate in the phosphate buffer medium, which in turn weakens the Ca-alginate matrix core. In the presence of E. coli, the formulations were fermented and the release of prednisolone was accelerated. In conclusion, the buffer media affects formulation behavior and drug release, with the bicarbonate media providing a better simulation of in vivo behavior. Moreover, the susceptibility of the formulations to bacterial action indicates their suitability as carriers for colonic drug delivery.     

Theoretical Prediction of Induction Period from Transient Pore Evolvement in Polyester-Based Microparticles

A model was developed and compared to experimental results for prediction of the induction period during drug delivery from various compositions of biodegradable copolymer PLGA microparticles. The uniqueness of this model is that it considers transient pore evolvement and uses the kinetic parameters of polymer degradation, which are independent of experimental measurements of microparticle erosion, in its analysis. Delivery data from PLGA microparticles (50:50, 75:25, and 85:15) releasing ovalbumin (OVA, 46 kDa) and bovine serum albumin (BSA, 66 kDa) were determined and used as the model systems. Experimental measurements were carried out from 85 to 150 days depending on the PLGA characteristics. The predicted induction periods were approximately 45, 70, and 105 days for the release of both OVA and BSA from 50:50, 75:25, and 85:15 PLGA microparticles, respectively. Overall, these values were in very good agreement with experimentally estimated results. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:4477-4487, 2010     

Considerations using silver nitrate as a reference for in vitro tests with silver nanoparticles

Most in vitro tests regarding the cellular toxicology of nanoparticulate metals compare particle to associated metal ion exposure. However, it is also a fact, that for example silver ions are reduced by sugars or transformed to silver chloride by chloride salts which are abundant components of cell culture media. These reactions are likely to either complicate or even invalidate comparisons between effects of ions and particles. Here, we present a fast and quantitative method to determine particle formation and numbers in different cell culture media with non-destructive small-angle X-ray scattering (SAXS). Silver nitrate with a concentration of 25 μg Ag mL^− 1 was dissolved for up to 24 h at 37 °C in Dulbeccos Modified Eagle Medium (DMEM) with and without 10% fetal bovine serum (FBS) and a solution of D-glucose (4.5 μg mL^− 1), respectively. Silver nanoparticles were observed in all solutions after 5 min. The cell culture media displayed a limited particle-growth. FBS showed an effect on the polydispersity of the generated particles but after 5 min the overall particle size was nearly equal in FBS and non FBS supplemented medium. Particles in D-glucose were precipitating after 10 min. Particulate silver concentration was between 3 and 4 μg mL^− 1 in both cell culture media (CCM). These results should be taken into account when performing silver ion-toxicity experiments in relevant media.     

Clinical Pharmacokinetics of Paclitaxel Liposome with a New Route of Administration in Human Based on the Analysis with Ultra Performance Liquid Chromatography

We investigated the clinical pharmacokinetics of paclitaxel liposome with a new route of administration, which was intrapleural infusion, in nine advanced nonsmall-cell lung cancer (NSCLC) patients with malignant pleural effusions after a single administration. Paclitaxel concentrations were measured in pleural fluid and plasma using a simple and rapid ultra performance liquid chromatography (UPLC) method following intra-and inter-day validations. In subjects, AUC_0–96h values in pleural fluid and plasma were 17831 ± 6439 μgh/mL and 778 ± 328 μgh/mL, respectively, and T_max values were initial time and 6.67 h after administration and the corresponding C_max values were 558 ± 44 μg/mL and 12.89 ± 6.86 μg/mL, respectively. The T_{1/2 IP}, CL_IP and Vd_IP values in pleural fluid were 76 ± 48 h, 0.005 ± 0.002 L/hm² and 0.53 ± 0.23 L/m², respectively. The T_1/2,_pla, CL_pla, and Vd_pla values in plasma were 68.34 ± 56.74 h, 0.184 ± 0.080 L/hm², and 17.53 ± 16.57 L/m², respectively. However, some paclitaxel concentrations from several patients in plasma could not be detected at some designed time-points. Our results might offer new opportunities to design and determine individually appropriate therapeutic dosage regimens based on a pharmacokinetic profile.     

Melatonin releasing PLGA micro/nanoparticles and their effect on osteosarcoma cells

Melatonin loaded poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles and microparticles in the diameter of ～200?nm and 3.5?μm, respectively, were prepared by emulsion–diffusion–evaporation method. Melatonin entrapment into the particles was significantly improved with the addition of 0.2% (w/v) melatonin into the aqueous phase and encapsulation efficiencies were found as 14 and 27% for nanoparticles and microparticles, respectively. At the end of 40 days, ～70% of melatonin was released from both of particles, with high burst release. Both blank and melatonin loaded PLGA nanoparticles caused toxic effect on the MG-63 cells due to their uptake by the cells. However, when 0.05?mg microparticle that is carrying ～1.7?μg melatonin was added to the cm² of culture, inhibitory effect of melatonin on the cells were obviously observed. The results would provide an expectation about the usage of melatonin as an adjunct to the routine chemotherapy of osteosarcoma by encapsulating it into a polymeric carrier system.     

Protein–polyelectrolyte interactions: Monitoring particle formation and growth by nanoparticle tracking analysis and flow imaging microscopy

The purpose of this study was to investigate the formation and growth kinetics of complexes of proteins and oppositely charged polyelectrolytes. Equal volumes of IgG and dextran sulfate (DS) solutions, 0.01 mg/ml each in 10 mM phosphate, pH 6.2, were mixed. At different time points, samples were taken and analyzed by nanoparticle tracking analysis (NTA), Micro-Flow Imaging (MFI) and size-exclusion chromatography (SEC). SEC showed a huge drop in monomer content (approximately 85%) already 2 min after mixing, while a very high nanoparticle (size up to 500 nm) concentration (ca. 9 × 10⁸/ml) was detected by NTA. The nanoparticle concentration gradually decreased over time, while the average particle size increased. After a lag time of about 1.5 h, a steady increase in microparticles was measured by MFI. The microparticle concentration kept increasing up to about 1.5 × 10⁶/ml until it started to slightly decrease after 10 h. The average size of the microparticles remained in the low-μm range (1–2 μm) with a slight increase and broadening of the size distribution in time. The experimental data could be fitted with Smoluchowski’s perikinetic coagulation model, which was validated by studying particle growth kinetics in IgG:DS mixtures of different concentrations. In conclusion, the combination of NTA and MFI provided novel insight into the kinetics and mechanism of protein–polyelectrolyte complex formation.     

Effect of total and partial nephrectomy on the elimination of ciprofloxacin in humans

BackgroundRenal cell carcinoma (RCC) is the most common form of kidney cancer. Surgery is a standard procedure to resect the tumor during total (TN) or partial (nephron-sparing) nephrectomy (PN). Ciprofloxacin is most often administered at the usual intravenous dose of 100–400 mg/12 h. The application of such low doses of ciprofloxacin as 200 mg/24 h carries the risk of achieving subtherapeutic concentrations even in patients with limited renal function. The aim of the study was a comparison of concentrations and pharmacokinetics for ciprofloxacin at steady-state in patients after total and partial nephrectomy and evaluation of the effectiveness of the iv dose 200 mg/24 h against the theoretical value of MIC, 0.5 μg/ml.MethodsThe research was carried out on two groups of patients after nephrectomy: total (group 1, n = 21; mean [SD], age, 62.9 [14.4] years; weight, 76.0 [14.6] kg; creatinine clearance, clcr, 90.7 [22.2] ml/min) and partial (group 2, n = 15; 61.7 [9.3] years; 87.8 [16.4] kg; CL_CR, 107.8 [36.4] ml/min). The patients were treated with ciprofloxacin in the dose of 200 mg/24 h (iv). Plasma concentrations of ciprofloxacin at steady state were measured with validated HPLC method with UV detection.ResultsThe mean values of plasma concentrations of ciprofloxacin at steady state in group 1 and 2 were: C^ss_max, 2.012 and 1.345; C^ss_min, 0.437 and 0.244 μg/ml, respectively. The main pharmacokinetic parameters for ciprofloxacin in group 1 and 2 were as follows: AUC_(0–last), 30.9 [17.9] and 19.5 [8.7] μg h/ml; AUMC_(0–last), 177.91 [11.1] and 91.9 [66.5] μg h²/ ml; _t1/2β, 13.9 [7.7] and 9.8 [3.3] h; MRT, 16.5 [12.1] and 9.77 [5.4] h; V_d, 115.0 [67.2] and 142.2 [78.7] l; CL, 6.2 [3.3] and 10.8 [5.7] l/h, respectively. With the assumed MIC = 0.5 μg/ml, the values of C^ss_max/MIC < 10 and AUC/MIC < 125 were obtained in all the patients.ConclusionIn our patients we observed significant differences in some pharmacokinetic parameters of ciprofloxacin after two types of nephrectomy.