Delivery of an anticancer drug and a chemosensitizer to murine breast sarcoma by intratumoral injection of sulfopropyl dextran microspheres

An Updated Insight into Phytomolecules and Novel Approaches used in the Management of Breast Cancer

Breast cancer is a widespread condition that kills more women from cancer-related causes than any other type of cancer globally. Women who have estrogen-dependent, initial metastatic breast cancer frequently receive treatment with surgery, radiation therapy, and chemotherapy. They may also get more specialized treatments like tamoxifen or aromatase inhibitors (anastrozole or letrozole). The World Health Organisation reported in 2012 that by 2030, breast cancer will be more common worldwide. There are several phytochemicals, such as isoflavones, coumestans, lignans, and prenylflavonoides. Isoflavones have been shown in studies to prevent the spread of breast cancer and to trigger apoptosis. Targeting BCs in metastatic breast cancer may be made possible by combining well-formulated phytochemicals in nanoparticles or other novel drug delivery agents with currently accepted endocrine and/or conventional chemotherapies. Cell signaling, regulation of cell cycles, oxidative stress action, and inflammation could be positively impacted by phytoconstituents. They have the ability to alter non-coding RNAs, to prevent the proliferation and regeneration of cancer cells. The availability of novel approaches helps in disease targeting, safety, effectiveness and efficacy. The current literature helps to know the available drugs i.e. phytoconstituents or novel drug delivery like nanoparticle, microsphere, micelles, liposomes and neosomes. The literature has been taken from PubMed, Google Scholar, SciFinder, or other internet sites.

Advances in Nanomedicine Design: Multidisciplinary Strategies for Unmet Medical Needs

Globally, a rising burden of complex diseases takes a heavy toll on human lives and poses substantial clinical and economic challenges. This review covers nanomedicine and nanotechnology-enabled advanced drug delivery systems (DDS) designed to address various unmet medical needs. Key nanomedicine and DDSs, currently employed in the clinic to tackle some of these diseases, are discussed focusing on their versatility in diagnostics, anticancer therapy, and diabetes management. First-hand experiences from our own laboratory and the work of others are presented to provide insights into strategies to design and optimize nanomedicine- and nanotechnology-enabled DDS for enhancing therapeutic outcomes. Computational analysis is also briefly reviewed as a technology for rational design of controlled release DDS. Further explorations of DDS have illuminated the interplay of physiological barriers and their impact on DDS. It is demonstrated how such delivery systems can overcome these barriers for enhanced therapeutic efficacy and how new perspectives of next-generation DDS can be applied clinically.

Cefquinome-loaded microsphere formulations against Klebsiella pneumonia infection during experimental infections

The aim of this study was to prepare cefquinome-loaded polylactic acid microspheres and to evaluate their in vitro and in vivo characteristics and pharmacodynamics for the therapy of pneumonia in a rat model. Microspheres were prepared using a 0.7 mm two-fluid nozzle spray drier in one step resulting in spherical and smooth microspheres of uniform size (9.8 ± 3.6 μm). The encapsulation efficiency and drug loading of cefquinome were 91.6 ± 2.6% and 18.7 ± 1.2%, respectively. In vitro release of cefquinome from the microspheres was sustained for 36 h. Cefquinome-loaded polylactic acid microspheres as a drug delivery system was successful for clearing experimental Klebsiella pneumonia lung infections. A decrease in inflammatory cells and an inhibition of inflammatory cytokines TNF-α, IL-1β and IL-8 after microspheres treatment was found. Changes in cytokine levels and types are secondary manifestations of drug bactericidal effects. Rats were considered to be microbiologically cured because the bacterial load was less than 100 CFU/g. These results also indicated that the spray-drying method of loading therapeutic drug into polylactic acid microspheres is a straightforward and safe method for lung-targeting therapy in animals.

Connecting myelin-related and synaptic dysfunction in schizophrenia with SNP-rich gene expression hubs

Combining genome-wide mapping of SNP-rich regions in schizophrenics and gene expression data in all brain compartments across the human life span revealed that genes with promoters most frequently mutated in schizophrenia are expression hubs interacting with far more genes than the rest of the genome. We summed up the differentially methylated “expression neighbors” of genes that fall into one of 108 distinct schizophrenia-associated loci with high number of SNPs. Surprisingly, the number of expression neighbors of the genes in these loci were 35 times higher for the positively correlating genes (32 times higher for the negatively correlating ones) than for the rest of the ~16000 genes. While the genes in the 108 loci have little known impact in schizophrenia, we identified many more known schizophrenia-related important genes with a high degree of connectedness (e.g. MOBP, SYNGR1 and DGCR6), validating our approach. Both the most connected positive and negative hubs affected synapse-related genes the most, supporting the synaptic origin of schizophrenia. At least half of the top genes in both the correlating and anti-correlating categories are cancer-related, including oncogenes (RRAS and ALDOA), providing further insight into the observed inverse relationship between the two diseases.

Nanomedicine of synergistic drug combinations for cancer therapy - Strategies and perspectives

Nanomedicine of synergistic drug combinations has shown increasing significance in cancer therapy due to its promise in providing superior therapeutic benefits to the current drug combination therapy used in clinical practice. In this article, we will examine the rationale, principles, and advantages of applying nanocarriers to improve anticancer drug combination therapy, review the use of nanocarriers for delivery of a variety of combinations of different classes of anticancer agents including small molecule drugs and biologics, and discuss the challenges and future perspectives of the nanocarrier-based combination therapy. The goal of this review is to provide better understanding of this increasingly important new paradigm of cancer treatment and key considerations for rational design of nanomedicine of synergistic drug combinations for cancer therapy.

Toxicological and Pharmacological Evaluation of New Drug Candidates by in Vitro Robotic High-Throughput Cell Assays

A high-throughput cell-based fluorescence screening assay was used to determine the cytotoxic activity of various cytostatic reference agents, unknown compounds of natural sources and pharmaceutic standard excipients in different cell lines such as HEK-293 and DLD-1 cells. In this paper we exemplarily show results for a selection of compounds and excipients. The cytostatic agent piposulfan has a much higher cytotoxic activity in DLD-1 cells (EC50=0.001 mg/mL) than in HEK-293 cells (EC50=0.3 mg/mL) in contrast to busulfan and vinblastine where the EC50 values are close together in both cell lines.

From 113 tested compounds from natural sources the cytotoxic activity of 75 compounds showed no difference in both cell lines, 34 of them had a higher activity in HEK-293 cells than in DLD-1 cells and 4 compounds showed less cytotoxic activity in HEK-293 cells than in DLD-1 cells. We demonstrate the rather potent cytotoxic action of Cremophor EL; this finding is in accordance with previously published observations. The presented results demonstrate that the used assay system is reliable, enables the ranking of the cytotoxic potential of compounds of various chemical classes, and allows the determination of cell type-specific cytotoxicity. (JALA 2004;9:159-62)

Synergistic nanoparticulate drug combination overcomes multidrug resistance, increases efficacy, and reduces cardiotoxicity in a nonimmunocompromised breast tumor model

Anthracyclines, commonly employed for cancer chemotherapy, suffer from dose-limiting cardiotoxicity and poor efficacy due to multidrug resistance (MDR). We previously demonstrated that simultaneous delivery of the synergistic drugs doxorubicin (DOX) and mitomycin C (MMC) by polymer-lipid hybrid nanoparticles (PLN) circumvented MDR, increased efficacy, and reduced cardiotoxicity in immuncompromised mice superior to poly(ethylene glycol)-coated (PEGylated) lipososmal DOX (PLD). Herein it is shown that the DOX-MMC combination was also synergistic in MDR EMT6/AR1 murine breast cancer cells and that their nanoparticle formulations were able to overcome the MDR phenotype. In contrast PLD exhibited little or no effect on the MDR cells. For the first time, these differences in in vitro efficacy are shown to be strongly correlated with cellular uptake and intracellular distribution of DOX brought about by DOX formulations (e.g., free solution, PLN vs PLD). To take into consideration the role of an intact immune system and tumor stroma in the response of host and tumor to chemotherapy, use was made of nonimmunocomprised mouse models to study the dose tolerance, cardiotoxicity, and efficacy of DOX-MMC coloaded PLN (DMsPLN) compared to PLD. DMsPLN treatment at 50 mg/m(2) DOX and 17 mg/m(2) of MMC singly or once every 4 days for 4 cycles were well tolerated by the mice without elevated systemic toxicity blood markers or myocardial damage. In contrast, PLD was limited to a single treatment due to significant total weight loss. The DMsPLN treatment delayed tumor growth up to 312% and 28% in EMT6/WT and EMT6/AR1 models, respectively. This work supports the translational value of DMsPLN for the aggressive management of either naïve or anthracycline-resistant tumors.

Anti-cancer effects of newly developed chemotherapeutic agent, glycoconjugated palladium (II) complex, against cisplatin-resistant gastric cancer cells

Background

Cisplatin (CDDP) is the most frequently used chemotherapeutic agent for various types of advanced cancer, including gastric cancer. However, almost all cancer cells acquire resistance against CDDP, and this phenomenon adversely affects prognosis. Thus, new chemotherapeutic agents that can overcome the CDDP-resistant cancer cells will improve the survival of advanced cancer patients.

Methods

We synthesized new glycoconjugated platinum (II) and palladium (II) complexes, [PtCl₂ (L)] and [PdCl₂ (L)]. CDDP-resistant gastric cancer cell lines were established by continuous exposure to CDDP, and gene expression in the CDDP-resistant gastric cancer cells was analyzed. The cytotoxicity and apoptosis induced by [PtCl₂ (L)] and [PdCl₂ (L)] in CDDP-sensitive and CDDP-resistant gastric cancer cells were evaluated. DNA double-strand breaks by drugs were assessed by evaluating phosphorylated histone H2AX. Xenograft tumor mouse models were established and antitumor effects were also examined in vivo.

Results

CDDP-resistant gastric cancer cells exhibit ABCB1 and CDKN2A gene up-regulation, as compared with CDDP-sensitive gastric cancer cells. In the analyses of CDDP-resistant gastric cancer cells, [PdCl₂ (L)] overcame cross-resistance to CDDP in vitro and in vivo. [PdCl₂ (L)] induced DNA double-strand breaks.

Conclusion

These results indicate that [PdCl₂ (L)] is a potent chemotherapeutic agent for CDDP-resistant gastric cancer and may have clinical applications.

Chemotherapy targeting by DNA capture in viral protein particles

AIM

This study tests the hypothesis that DNA intercalation and electrophilic interactions can be exploited to noncovalently assemble doxorubicin in a viral protein nanoparticle designed to target and penetrate tumor cells through ligand-directed delivery. We further test whether this new paradigm of doxorubicin targeting shows therapeutic efficacy and safety in vitro and in vivo.

MATERIALS & METHODS

We tested serum stability, tumor targeting and therapeutic efficacy in vitro and in vivo using biochemical, microscopy and cytotoxicity assays.

RESULTS

Self-assembly formed approximately 10-nm diameter serum-stable nanoparticles that can target and ablate HER2+ tumors at >10× lower dose compared with untargeted doxorubicin, while sparing the heart after intravenous delivery. The targeted nanoparticle tested here allows doxorubicin potency to remain unaltered during assembly, transport and release into target cells,while avoiding peripheral tissue damage and enabling lower, and thus safer, drug dose for tumor killing.

CONCLUSION

This nanoparticle may be an improved alternative to chemical conjugates and signal-blocking antibodies for tumor-targeted treatment.

Role of nanomedicine in reversing drug resistance mediated by ATP binding cassette transporters and P-glycoprotein in melanoma

Multidrug resistance (MDR) is one of the most common complex phenomenons exhibited by cancer cells. It is a very common property of melanoma postchemotherapy. MDR transporters, ATP binding cassette (ABC) transporters, play a critical role in conferring this property to melanoma cells. miRNA are post-transcriptional regulators that regulate the expression of these ABC transporters. Targeting these miRNA, in turn targeting ABC transporters with the help of nanodelivery systems to overcome drug resistance, is the primary focus for attaining successful treatment methods for drug-resistant melanoma. These delivery systems are endocytosed by the cancer cells and do not require ABC transporters for their delivery, being a promising therapeutic measure for melanoma.

Spray-dried doxorubicin-albumin microparticulate systems for treatment of multidrug resistant melanomas

As multidrug resistance continues to be a problem in cancer treatment, controlled release delivery systems, such as microspheres, may aid to give a slower release of anticancer drugs into drug resistant tumor cells. In this study doxorubicin microspheres microencapsulated in an albumin matrix were prepared via the spray-drying method and characterized for particle size, content analysis, and release studies. They were then evaluated in vitro using drug resistant murine melanoma tumor cells for uptake and efflux studies. Spray-drying produced a dispersed powder with a mean particle size of 4.91 ± 1.2 µm, 60% product yield, and encapsulation efficiency of 85% and a ζ potential range of 37 to -40 mV. Intracellular doxorubicin concentrations were higher in drug resistant tumor cells treated with microspheres as opposed to solution, and efflux of doxorubicin from the tumor cell was inhibited. Greater cytotoxic effects were seen in tumor cells treated with doxorubicin microspheres versus solution up to and after 3 days. In vivo pharmacokinetic studies conducted in male Sprague-Dawley rats, revealed a plasma-level time curve indicative of a two-compartment model, and showed prolonged half-life of doxorubicin, greater area under the plasma concentration time curve, and increased plasma concentrations of doxorubicin in rats at 8 and 24 h after administration of doxorubicin microspheres.

Injectable intratumoral depot of thermally responsive polypeptide-radionuclide conjugates delays tumor progression in a mouse model

This study evaluated a biodegradable drug delivery system for local cancer radiotherapy consisting of a thermally sensitive elastin-like polypeptide (ELP) conjugated to a therapeutic radionuclide. Two ELPs (49 kDa) were synthesized using genetic engineering to test the hypothesis that injectable biopolymeric depots can retain radionuclides locally and reduce the growth of tumors. A thermally sensitive polypeptide, ELP(1), was designed to spontaneously undergo a soluble-insoluble phase transition (forming viscous microparticles) between room temperature and body temperature upon intratumoral injection, while ELP(2) was designed to remain soluble upon injection and to serve as a negative control for the effect of aggregate assembly. After intratumoral administration of radionuclide conjugates of ELPs into implanted tumor xenografts in nude mice, their retention within the tumor, spatio-temporal distribution, and therapeutic effect were quantified. The residence time of the radionuclide-ELP(1) in the tumor was significantly longer than the thermally insensitive ELP(2) conjugate. In addition, the thermal transition of ELP(1) significantly protected the conjugated radionuclide from dehalogenation, whereas the conjugated radionuclide on ELP(2) was quickly eliminated from the tumor and cleaved from the biopolymer. These attributes of the thermally sensitive ELP(1) depot improved the antitumor efficacy of iodine-131 compared to the soluble ELP(2) control. This novel injectable and biodegradable depot has the potential to control advanced-stage cancers by reducing the bulk of inoperable tumors, enabling surgical removal of de-bulked tumors, and preserving healthy tissues.

Characterization of a microsphere formulation containing glucose oxidase and its in vivo efficacy in a murine solid tumor model

PURPOSE

This work focused on the characterization and in vitro/in vivo evaluation of an alginate/chitosan microsphere (ACMS) formulation of glucose oxidase (GOX) for the locoregional delivery of reactive oxygen species for the treatment of solid tumors.

METHODS

The GOX distribution and ACMS composition were determined by confocal laser scanning microscopy and X-ray photoelectron spectroscopy. The mechanism of GOX loading and GOX-polymer interactions were examined with Fourier transform infrared spectroscopy and differential scanning calorimetry. In vitro cytotoxicity and in vivo efficacy of GOX-encapsulated ACMS (ACMS-GOX) were evaluated in EMT6 breast cancer cells and solid tumors.

RESULTS

GOX was loaded into calcium alginate (CaAlg) gel beads via electrostatic interaction and the CaAlg-GOX-chitosan complexation likely stabilized GOX. Higher concentrations of GOX near the surface of ACMS were detected. GOX retained its integrity upon adsorption to CaAlg gel beads during the coating and after release from ACMS. ACMS-GOX exhibited cytotoxicity to the breast cancer cells in vitro and their efficacy increased with increasing incubation time. Intratumorally delivered ACMS-GOX significantly delayed tumor growth with much lower general toxicity than free GOX.

CONCLUSION

The results suggest that the ACMS-GOX formulation has the potential for the intratumoral delivery of therapeutic proteins to treat solid tumors.

A novel doxorubicin-mitomycin C co-encapsulated nanoparticle formulation exhibits anti-cancer synergy in multidrug resistant human breast cancer cells

Anthracycline-containing treatment regimens are currently the most widely employed regimens for the management of breast cancer. These drug combinations are often designed based on non-cross resistance and minimal overlapping toxicity rather than drug synergism. Moreover, aggressive doses are normally used in chemotherapy to achieve a greater therapeutic benefit at the cost of more acute and long-term toxic effects. To increase chemotherapeutic efficacy while decreasing toxic effects, rational design of drug synergy-based regimens is needed. Our previous work showed a synergistic effect of doxorubicin (DOX) and mitomycin C (MMC) on murine breast cancer cells in vitro and improved efficacy and reduced systemic toxicity of DOX-loaded solid polymer-lipid hybrid nanoparticles (PLN) in animal models of breast cancer. Herein we have demonstrated true anticancer synergy of concurrently applied DOX and MMC, and have rationally designed PLN to effectively deliver this combination to multidrug resistant (MDR) MDA435/LCC6 human breast cancer cells. DOX-MMC co-loaded PLN were effective in killing MDR cells at 20-30-fold lower doses than the free drugs. This synergistic cell killing was correlated with enhanced induction of DNA double strand breaks that preceded apoptosis. Importantly, co-encapsulation of dual agents into a nanoparticle formulation was much more effective than concurrent application of single agent-containing PLN, demonstrating the requirement of simultaneous uptake of both drugs by the same cells to enhance the drug synergy. The rationally designed combination chemotherapeutic PLN can overcome multidrug resistance at a significantly lower dose than free drugs, exhibiting the potential to enhance chemotherapy and reduce the therapeutic limitations imposed by systemic toxicity.

In vivo evaluation of a new polymer-lipid hybrid nanoparticle (PLN) formulation of doxorubicin in a murine solid tumor model

The purpose of this study is to evaluate the in vivo efficacy, unwanted toxicity and loco-regional distribution of a doxorubicin-loaded polymer-lipid hybrid nanoparticle (Dox-PLN) formulation in a murine solid tumor model after intratumoral injection. Dox-PLN were prepared by dispersing Dox in stearic acid and tristearin, with subsequent addition of a novel anionic polymer HPESO (hydrolyzed polymer of epoxidized soybean oil) to enhance the drug incorporation in the lipids. Solid tumors were obtained by injecting EMT6 mouse mammary cancer cells intramuscularly into the hind legs of BALB/c mice. Dox-PLN, blank PLN or surfactant formulations were injected intratumorally (IT) when tumors reached approximately 0.3 g. In vivo efficacy of treatment was measured by tumor growth delay (TGD), defined as the delay in time for the tumor to grow to 1.13 g relative to the untreated control. Signs of unwanted drug toxicity, the histology and morphology of tumor and heart tissues, and the IT distribution of Dox-PLN after IT treatment were examined or monitored. IT-administered Dox-PLN resulted in 70% and 100% TGD (p<0.01) for Dox doses of 0.1 and 0.2 mg, respectively. Dox-PLN treated tumors developed substantially larger central necrotic regions than the untreated tumors, with Dox-PLN residues extensively distributed among the dead cell debris, suggesting that the anticancer effect of Dox-PLN was mainly a combined result of IT nanoparticle distribution and short-ranged, sustained drug release. Except for two of fifteen mice receiving the higher 0.2 mg Dox dose showing transient fur-roughing, all Dox-PLN treated mice showed no signs of toxicity. The present study demonstrates that Dox-PLN possess significant in vivo cytotoxic activity against solid tumors with minimal systemic toxicity. IT administered Dox-PLN have the potential to improve the therapeutic index of loco-regional solid tumor chemotherapy.

Controlled release of bioactive doxorubicin from microspheres embedded within gelatin scaffolds

We have encapsulated the chemotherapeutic agent doxorubicin into biodegradable polymer microspheres, and incorporated these microspheres into gelatin scaffolds, resulting in a controlled delivery system. Doxorubicin was encapsulated in poly(D,L-lactide-co-glycolide) (PLGA) using a double emulsion/solvent extraction method. Characterization of the microspheres including diameter, surface morphology, and in vitro drug release was determined. The release of doxorubicin up to 30 days in phosphate buffered solution was assessed by measuring the absorbance of the releasate solution. Gelatin scaffolds were crosslinked using glutaraldehyde and microspheres were added to gelatin during gelation. The murine mammary mouse tumor cell line, 4T1, was treated with various doses of doxorubicin. A propidium iodide assay was utilized to visualize dead cells. Using a Transwell basket assay, PLGA microspheres and gelatin constructs were suspended above 4T1 cells for 48 h. Viable cells were determined using the CyQUANT cell proliferation assay. Results indicate that the release was controlled by the incorporation of PLGA microspheres into gelatin constructs. A significant difference was seen in the cumulative release over days 5-16 (p < 0.05). The bioactivity of doxorubicin released from the microspheres and scaffolds was maintained as proven by significant reduction in viable cells after treatment with PLGA microspheres as well as with the gelatin constructs (p < 0.001). The drug-polymer conjugate can be used as a controlled drug delivery system in a biocompatible scaffold that could potentially promote preservation of soft tissue contour.

A new polymer-lipid hybrid nanoparticle system increases cytotoxicity of doxorubicin against multidrug-resistant human breast cancer cells

PURPOSE

This work is intended to develop and evaluate a new polymer-lipid hybrid nanoparticle system that can efficiently load and release water-soluble anticancer drug doxorubicin hydrochloride (Dox) and enhance Dox toxicity against multidrug-resistant (MDR) cancer cells.

METHODS

Cationic Dox was complexed with a new soybean-oil-based anionic polymer and dispersed together with a lipid in water to form Dox-loaded solid lipid nanoparticles (Dox-SLNs). Drug loading and release properties were measured spectrophotometrically. The in vitro cytotoxicity of Dox-SLN and the excipients in an MDR human breast cancer cell line (MDA435/LCC6/MDR1) and its wild-type line were evaluated by trypan blue exclusion and clonogenic assays. Cellular uptake and retention of Dox were determined with a microplate fluorometer.

RESULTS

Dox-SLNs were prepared with a drug encapsulation efficiency of 60-80% and a particle size range of 80-350 nm. About 50% of the loaded drug was released in the first few hours and an additional 10-20% in 2 weeks. Treatment of the MDR cells with Dox-SLN resulted in over 8-fold increase in cell kill when compared to Dox solution treatment at equivalent doses. The blank SLN and the excipients exhibited little cytotoxicity. The biological activity of the released Dox remained unchanged from fresh, free Dox. Cellular Dox uptake and retention by the MDR cells were both significantly enhanced (p < 0.05) when Dox was delivered in Dox-SLN form.

CONCLUSIONS

The new polymer-lipid hybrid nanoparticle system is effective for delivery of Dox and enhances its efficacy against MDR breast cancer cells.

Prediction of kinetics of doxorubicin release from sulfopropyl dextran ion-exchange microspheres using artificial neural networks

The purpose of this work was to develop artificial neural networks (ANN) models to predict in vitro release kinetics of doxorubicin (Dox) delivered by sulfopropyl dextran ion-exchange microspheres. Four ANN models for responses at different time points were developed to describe the release profiles of Dox. Model selection was performed using the Akaike information criterion (AIC). Sixteen data sets were used to train the ANN models and two data sets for the validation. Good correlations were obtained between the observed and predicted release profiles for the two randomly selected validation data sets. The difference factor (f1) and similarity factor (f2) between the ANN predicted and the observed release profiles indicated good performance of the ANN models. The established models were then applied to predict release kinetics of Dox from the microspheres of various initial loadings in media of different ionic strengths and NaCl/CaCl2 ratios. The results suggested that ANN offered a flexible and effective approach to predicting the kinetics of Dox release from the ion-exchange microspheres.

A new approach to the in vivo and in vitro investigation of drug release from locoregionally delivered microspheres

The purpose of this work was to determine the in vivo release profile of doxorubicin (Dox) delivered locoregionally by dextran-based microspheres (MS) and to develop an in vitro method for predicting in vivo drug release from MS-- in vitro-in vivo correlation (IVIVC). For the determination of in vivo Dox release, drug-loaded MS were placed into hollow fibers (HF) and implanted subcutaneously into C3H mice. Samples were retrieved at various times following implantation, MS removed from HF, and the amount of Dox remaining determined via ultraviolet/visible (UV/Vis) spectrophotometry. Various in vitro systems were designed and investigated for their ability to link in vivo and in vitro release profiles, including an open system (e.g. a column) with continuous flow of release medium at different flow rates and closed systems (e.g. a cuvette) using different release media and conditions. About 34% of loaded Dox was released from MS in vivo at 48 h. Only an incremental release was observed over the ensuing 72 h. The release kinetics of Dox from MS using three of the investigated in vitro systems, column system and HF immersed in a buffer solution or growth medium gave release profiles that were highly correlated with the in vivo release profile (r(2)>0.9). The relationships, both linear and non-linear, suggest that Level A IVIVC models can be developed for Dox release from locoregionally delivered MS using specially designed release systems.

Development of solid lipid nanoparticles containing ionically complexed chemotherapeutic drugs and chemosensitizers

The purpose of this study was to develop and characterize a solid lipid nanoparticle (SLN) system containing an anionic polymer for the delivery of cationic antineoplastic agents and chemosensitizers. Ionic complexation was utilized to enhance the loading of these highly water-soluble drugs. The influence of anionic compounds and polymers on drug partition and loading into SLNs was investigated, and dextran sulfate (DS) was found to be the most suitable among those studied. SLNs loaded with doxorubicin and various model chemosensitizers (e.g., verapamil) were thus prepared by incorporating DS using a microemulsion method. The particle size was measured with photon correlation spectroscopy. The mean diameter of the SLNs ranged from 180 to 300 nm, depending on the type and content of the drug and the polymer. The particles possessed weakly negative surface charges as determined by zeta potential measurements. Most polymer-loaded SLNs released half of the drug in the first a few hours and the remaining drug in 15 h or more. The presence of counterions in the medium, especially divalent ions, promoted drug release. Dual drug (doxorubicin/verapamil or quinidine/verapamil)-loaded DS-SLNs were also formulated, which released both drugs without noticeable interference to each other. These studies have laid the foundation for a "one-bullet" dosage form that may provide convenient and effective delivery of multiple drug treatment of tumors.