CFD-DEM -DDM Model for Spray Coating Process in a Wurster Coater.

A multiscale model by coupling computational fluid dynamics (CFD) with a discrete element model (DEM) and discrete droplet model (DDM) is developed to simulate a lab-scale Wurster coater. Two case studies are conducted to study the effect of particle shape in the system. In the first case study, 45,000 spherical particles are coated for 5 s while for the second case study, a mixture of 22,500 spherical particles and 22,500 cylindrical particles is simulated. The residence time distributions (RTD) of particles in different spray zones are compared, and the best spray zone is derived by analysing the positions of spray droplet-particle contacts. The simulation results show that the RTD of the particles within an accurate spray zone can provide valuable information on the final product's particles size distribution. Furthermore, the coefficient of variation (COV) for the coating mass received by the particles is studied for both case studies.

Comparative binder efficiency modeling of dry granulation binders using roller compaction.

Roller compaction parameters' impact on granules and tableting properties of coprocessed Avicel® DG [ADG], a physical mixture of the two components at the same composition present in ADG [PADCP], and microcrystalline cellulose and Kollidon® VA-64 Fine physical mixture [KVA64] was quantified by analysis of variance (ANOVA) and multivariate methods. Roller force, roller gap, and roller speed levels were selected for evaluation. A 33 full-factorial experimental design with three center points for roller force, roller gap, and roller speed was used. The response parameters studied were granule-to-fines (GF) ratio, compressibility index (CI), tablet thickness (TT), tablet friability (TF), tablet breaking force (TBF) and disintegration time (DT). A model acetaminophen tablet formulation was roller granulated and tableted at 10 kg scale. Principal component analysis of ADG and PADCP formulations were separated from KVA64 formulations, indicating different granule and tableting properties were binder dependent. This difference in binder performance was also confirmed by ANOVA. The ANOVA also showed that there were no statistical performance differences between coprocessed ADG and its comparable physical blend with the exception of TT. Principal component regression (PCR) analyses of ADG and PADCP revealed that these excipients exhibited a statistically significant negative effect on granules-to-fine (GF) ratio, TT, TBF, and DT. KVA64 demonstrated a positive effect on these parameters. The KVA64 physical mixture demonstrated an overall better performance and binding capability. This study strongly suggests that there is no performance advantage of coprocessed Avicel® DG when compared to a physical mixture of the two components at the same composition.

Development of idarubicin and doxorubicin solid lipid nanoparticles to overcome Pgp-mediated multiple drug resistance in leukemia.

The objectives of these studies were to investigate and compare solid lipid nanoparticles (SLNs) of two anthracyclines, idarubicin (IDA) and doxorubicin (DOX), against Pgp-mediated multiple drug resistance (MDR) in-vitro and in-vivo using different human and murine cancer cell models. IDA and DOX SLNs were developed from warm microemulsion precursors comprising emulsifying wax as the oil phase, and polyoxyl 20-stearyl ether (Brij 78) and D-alpha-tocopheryl polyethylene glycol succinate (Vitamin E TPGS) as the surfactants. Anionic ion-pairing agents, sodium taurodeoxycholate (STDC) and sodium tetradecyl sulfate (STS), were used to neutralize the charges of the cationic anthracyclines and enhance entrapment of the drugs in the SLN. The in-vitro cytotoxicity results showed that the IC50 value of DOX NPs was 9-fold lower than that of free DOX solution in resistant P388/ADR cell line. In contrast, free IDA had comparable IC50 values as IDA NPs in Pgp-overexpressing P388/ADR and HCT-15 cells. In the in-vivo P388/ADR leukemia mouse model, the median survival time of DOX NPs was significantly greater than that of free DOX, and controls. In contrast, free IDA was equally as effective as IDA NPs in P388 and Pgp-overexpressing HCT-15 mouse tumor models. The cell uptake of IDA formulated as free IDA and IDA NPs was comparable in Pgp-overexpressing cells. In conclusion, DOX NPs could overcome Pgp-mediated MDR both in-vitro in P388/ADR leukemia cells and in-vivo in the murine leukemia mouse model. The present study suggests that our SLNs may offer potential to deliver anticancer drugs for the treatment of Pgp-mediated MDR in leukemia; however, selection of target drug may be very important.

Elevated copper and oxidative stress in cancer cells as a target for cancer treatment.

As we gain a better understanding of the factors affecting cancer etiology, we can design improved treatment strategies. Over the past three to four decades, there have been numerous successful efforts in recognizing important cellular proteins essential in cancer growth and therefore these proteins have been targeted for cancer treatment. However, studies have shown that targeting one or two proteins in the complex cancer cascade may not be sufficient in controlling and/or inhibiting cancer growth. Therefore, there is a need to examine features which are potentially involved in multiple facets of cancer development. In this review we discuss the targeting of the elevated copper (both in serum and tumor) and oxidative stress levels in cancer with the aid of a copper chelator d-penicillamine (d-pen) for potential cancer treatment. Numerous studies in the literature have reported that both the serum and tumor copper levels are elevated in a variety of malignancies, including both solid tumor and blood cancer. Further, the elevated copper levels have been shown to be directly correlated to cancer progression. Enhanced levels of intrinsic oxidative stress has been shown in variety of tumors, possibly due to the combination of factors such as elevated active metabolism, mitochondrial mutation, cytokines, and inflammation. The cancer cells under sustained ROS stress tend to heavily utilize adaptation mechanisms and may exhaust cellular ROS-buffering capacity. Therefore, the elevated copper levels and increased oxidative stress in cancer cells provide for a prospect of selective cancer treatment.

Enhanced intracellular delivery of the reactive oxygen species (ROS)-generating copper chelator D-penicillamine via a novel gelatin--D-penicillamine conjugate.

D-Penicillamine (D-pen) is an established copper chelator. We have recently shown that the copper-catalyzed D-pen oxidation generates concentration-dependent hydrogen peroxide (H 2O 2). Additionally, D-pen coincubated with cupric sulfate resulted in cytotoxicity in human leukemia and breast cancer cells due to the extracellular generation of reactive oxygen species (ROS). The inherent physicochemical properties of D-pen such as its short in vivo half-life, low partition coefficient, and rapid metal catalyzed oxidation limit its intracellular uptake and the potential utility as an anticancer agent in vivo. Therefore, to enhance the intracellular delivery and to protect the thiol moiety of D-pen, we designed, synthesized, and evaluated a novel gelatin-D-pen conjugate. D-pen was covalently coupled to gelatin with a biologically reversible disulfide bond with the aid of a heterobifunctional cross-linker ( N-succinimidyl-3-(2-pyridyldithio)-propionate) (SPDP). Additionally, fluorescein-labeled gelatin-D-pen conjugate was synthesized for cell uptake studies. D-pen alone was shown not to enter leukemia cells. In contrast, the qualitative intracellular uptake of the conjugate in human leukemia cells (HL-60) was shown with confocal microscopy. The conjugate exhibited slow cell uptake (over the period of 48 to 72 h). A novel HPLC assay was developed to simultaneously quantify both D-pen and glutathione in a single run. The conjugate was shown to completely release D-pen in the presence of glutathione (1 mM) in approximately 3 h in PBS buffer, pH 7.4. The gelatin-D-pen conjugate resulted in significantly greater cytotoxicity compared to free D-pen, gelatin alone, and a physical mixture of gelatin and D-pen in human leukemia cells. Further studies are warranted to assess the potential of D-pen conjugate in the delivery of D-pen as a ROS generating anticancer agent.

Copper chelation by D-penicillamine generates reactive oxygen species that are cytotoxic to human leukemia and breast cancer cells.

Serum and tumor copper levels are significantly elevated in a variety of malignancies including breast, ovarian, gastric, lung, and leukemia. D-Penicillamine (D-pen), a copper-chelating agent, at low concentrations in the presence of copper generates concentration-dependent cytotoxic hydrogen peroxide (H(2)O(2)). The purpose of these studies was to investigate the in vitro cytotoxicity, intracellular reactive oxygen species (ROS) generation, and the reduction in intracellular thiol levels due to H(2)O(2) and other ROS generated from copper-catalyzed D-pen oxidation in human breast cancer cells (BT474, MCF-7) and human leukemia cells (HL-60, HL-60/VCR, HL-60/ADR). D-pen (< or = 400 microM) in the presence of cupric sulfate (10 microM) resulted in concentration-dependent cytotoxicity. Catalase was able to completely protect the cells, substantiating the involvement of H(2)O(2) in cancer cell cytotoxicity. A linear correlation between the D-pen concentration and the intracellular ROS generated was shown in both breast cancer and leukemia cells. D-pen in the presence of copper also resulted in a reduction in intracellular reduced thiol levels. The H(2)O(2)-mediated cytotoxicity was greater in leukemia cells compared to breast cancer cells. These results support the hypothesis that D-pen can be employed as a cytotoxic copper-chelating agent based on its ROS-generating ability.

An investigation into copper catalyzed D-penicillamine oxidation and subsequent hydrogen peroxide generation.

D-Penicillamine is a potent copper (Cu) chelating agent. D-Pen reduces Cu(II) to Cu(I) in the process of chelation while at the same time being oxidized to D-penicillamine disulfide. It has been proposed that hydrogen peroxide is generated during this process. However, definitive experimental proof that hydrogen peroxide is generated remains lacking. Thus, the major aims of these studies were to confirm and quantitatively assess the in vitro production of hydrogen peroxide during copper catalyzed D-penicillamine oxidation. The potential cytotoxic effect of hydrogen peroxide generation was also investigated in vitro against MCF-7 human breast cancer cells. Cell cytotoxicity resulting from the incubation of D-penicillamine with copper was compared to that of D-penicillamine, copper and hydrogen peroxide. The mechanism of copper catalyzed D-penicillamine oxidation and simultaneous hydrogen peroxide production was investigated as a function of time, concentration of cupric sulfate or ferric chloride, temperature, pH, anaerobic condition and chelators such as ethylenediaminetetraacetic acid and bathocuproinedisulfonic acid. A simple, sensitive and rapid HPLC assay was developed to simultaneously detect D-penicillamine, its major oxidation product D-penicillamine disulfide, and hydrogen peroxide in a single run. Hydrogen peroxide was shown to be generated in a concentration dependent manner as a result of D-penicillamine oxidation in the presence of cupric sulfate. Chelators such as ethylenediaminetetraacetic acid and bathocuproinedisulfonic acid were able to inhibit D-penicillamine oxidation. The incubation of MCF-7 human breast cancer cells with D-penicillamine plus cupric sulfate resulted in the production of reactive oxygen species within the cell and cytotoxicity that was comparable to free hydrogen peroxide.

Novel D-penicillamine carrying nanoparticles for metal chelation therapy in Alzheimer's and other CNS diseases.

Metal ions accumulate in the brain with aging and in several neurodegenerative diseases. Aside from the copper storage disease, Wilson's disease, recent attention has focused on the accumulation of zinc, copper and iron in the Alzheimer's disease (AD) brain and the accumulation of iron in Parkinson's disease. In particular, the parenchymal deposition of beta-amyloid (Abeta) and its interaction with metal ions has been postulated to play a role in the progression of AD. Thus, the strategy of lowering brain metal ions and targeting the interaction of Abeta peptide and metal ions through the administration of chelators has merit. Our recent finding that nanoparticle delivery systems can cross the blood-brain barrier has led us to investigate whether chelators delivered conjugated to nanoparticles could act to reverse metal ion induced protein precipitation. In the present studies, the Cu (I) chelator D-penicillamine was covalently conjugated to nanoparticles via a disulfide bond or a thioether bond. Nanoparticle-chelator conjugates were stable between pH 6-8 in aqueous suspension if stored at 4 degrees C, and did not aggregate when challenged with salts and serum. Release of D-penicillamine from the nanoparticles was achieved using reducing agents such as dithiothreitol (as a model for glutathione). Nanoparticles treated only under reducing conditions that released the conjugated D-penicillamine were able to effectively resolubilize copper-Abeta (1-42) aggregates. These results indicate that nanoparticles have potential to deliver D-penicillamine to the brain for the prevention of Abeta (1-42) accumulation, as well as to reduce metal ion accumulation in other CNS diseases.

Formulation and characterization of Paclitaxel, 5-FU and Paclitaxel + 5-FU microspheres.

The purpose of this study was to compare the combination (Paclitaxel + 5-FU microspheres) with a single drug chemotherapy (Paclitaxel and 5-FU microspheres) against metastatic breast cancer cell line (MDA-MB 435 S). The physicochemical characteristics of the microspheres (i.e. encapsulation efficiency, particle size distribution, in vitro release, thermal characteristics) were studied. The results demonstrated that the encapsulation efficiency of Paclitaxel was high (90%) when the drug was encapsulated in poly(lactic-co-glycolic acid) (PLGA) microparticles with or without 5-fluorouracil (5-FU). However, the encapsulation efficiency of 5-FU was low (19%) and increased to 30% when the drug was encapsulated with Paclitaxel. The mean particle size of microspheres was 2.5microm and were spherical in shape. The in vitro release of both 5-FU and Paclitaxel from the microspheres was relatively fast initially followed by a slower and more controlled release. The cytotoxic activity of Paclitaxel microspheres was far greater compared to either the microspheres containing 5-FU + Paclitaxel or 5-FU alone. Overall results demonstrated that incorporation of Paclitaxel or 5-FU in microspheres enhances the cytotoxicity in more controlled manner compared to that of free drugs and also that careful consideration should be made when combining drugs acting in different phases of cell cycle.