Enhanced Cellular Uptake and Transport of Bovine Lactoferrin Using Pectin- and Chitosan-Modified Solid Lipid Nanoparticles.

AIM: The aim of this project is to use pectin- and chitosan-modified solid lipid nanoparticles for bovine lactoferrin to enhance its cellular uptake and transport. METHODS: Solid lipid particles containing bovine lactoferrin (bLf) were formulated through the solvent evaporation technique, incorporating stearic acid along with either chitosan or pectin modification. bLf cellular uptake and transport were evaluated in vitro using the human adenocarcinoma cell line Caco-2 cell model. RESULTS AND DISCUSSION: The bLf-loaded SLPs showed no significant effect on cytotoxicity and did not induce apoptosis within the eight-hour investigation. The use of confocal laser scanning microscopy confirmed that bLf follows the receptor-mediated endocytosis, whereas the primary mechanism for the cellular uptake of SLPs was endocytosis. The bLf-loaded SLPs had significantly more cellular uptake compared to bLf alone, and it was observed that this impact varied based on the time, temperature, and concentration. Verapamil and EDTA were determined to raise the apparent permeability coefficients (App) of bLf and bLf-loaded SLPs. CONCLUSION: This occurred because they hindered efflux by interacting with P-glycoproteins and had a penetration-enhancing influence. These findings propose the possibility of an additional absorption mechanism for SLPs, potentially involving active transportation facilitated by the P-glycoprotein transporter in Caco-2 cells. These results suggest that SLPs have the potential to be applied as effective carriers to improve the oral bioavailability of proteins and peptides.

Natural mineral fibers: conducting inhalation toxicology studies-part B: development of a nose-only exposure system for repeat-exposure in vivo study of Libby amphibole aerosol.

BACKGROUND: Exposure to asbestos is associated with malignant and nonmalignant respiratory disease. To strengthen the scientific basis for risk assessment on fibers, the National Institute of Environmental Health Sciences (NIEHS) has initiated a series of studies to address fundamental questions on the toxicology of naturally occurring asbestos and related mineral fibers after inhalation exposure. A prototype nose-only exposure system was previously developed and validated. The prototype system was expanded to a large-scale exposure system in this study for conducting subsequent in vivo rodent inhalation studies of Libby amphibole (LA) 2007, selected as a model fiber. RESULTS: The exposure system consisting of six exposure carousels was able to independently deliver stable LA 2007 aerosol to individual carousels at target concentrations of 0 (control group), 0.1, 0.3, 1, 3, or 10 mg/m3. A single aerosol generator was used to provide aerosol to all carousels to ensure that exposure atmospheres were chemically and physically similar, with aerosol concentration as the only major variable among the carousels. Transmission electron microscopy (TEM) coupled with energy dispersive spectrometry (EDS) and selected area electron diffraction (SAED) analysis of aerosol samples collected at the exposure ports indicated the fiber dimensions, chemical composition, and mineralogy were equivalent across exposure carousels and were comparable to the bulk LA 2007 material. CONCLUSION: The exposure system developed is ready for use in conducting nose-only inhalation toxicity studies of LA 2007 in rats. The exposure system is anticipated to have applicability for the inhalation toxicity evaluation of other natural mineral fibers of concern.

Natural mineral fibers: conducting inhalation toxicology studies - part A: Libby Amphibole aerosol generation and characterization method development.

BACKGROUND: Asbestos has been classified as a human carcinogen, and exposure may increase the risk of diseases associated with impaired respiratory function. As the range of health effects and airborne concentrations that result in health effects across asbestos-related natural mineral fiber types are not fully understood, the National Institute of Environmental Health Sciences has established a series of research studies to characterize hazards of natural mineral fibers after inhalation exposure. This paper presents the method development work of this research project. RESULTS: A prototype nose-only exposure system was fabricated to explore the feasibility of generating natural mineral fiber aerosol for in vivo inhalation toxicity studies. The prototype system consisted of a slide bar aerosol generator, a distribution/delivery system and an exposure carousel. Characterization tests conducted using Libby Amphibole 2007 (LA 2007) demonstrated the prototype system delivered stable and controllable aerosol concentration to the exposure carousel. Transmission electron microscopy (TEM) analysis of aerosol samples collected at the exposure port showed the average fiber length and width were comparable to the bulk LA 2007. TEM coupled with energy dispersive spectrometry (EDS) and selected area electron diffraction (SAED) analysis further confirmed fibers from the aerosol samples were consistent with the bulk LA 2007 chemically and physically. CONCLUSIONS: Characterization of the prototype system demonstrated feasibility of generating LA 2007 fiber aerosols appropriate for in vivo inhalation toxicity studies. The methods developed in this study are suitable to apply to a multiple-carousel exposure system for a rat inhalation toxicity testing using LA 2007.

Early discontinuation of adjuvant chemotherapy in patients with early-stage pancreatic cancer correlates with inferior survival: A multicenter population-based cohort study.

BACKGROUND: The current study aimed to determine the association between timing and completion of adjuvant chemotherapy and outcomes in real-world patients with early-stage pancreatic cancer. METHODS: In this multi-center cohort study patients with early-stage pancreatic cancer who were diagnosed from 2007-2017 and underwent complete resection in the province of Saskatchewan were examined. Cox proportional multivariate analyses were performed for correlation with recurrence and survival. RESULTS: Of 168 patients, 71 eligible patients with median age of 69 years and M:F of 37:34 were identified. Median time to the start of adjuvant therapy from surgery was 73 days. Of all patients, 49 (69%) patients completed adjuvant chemotherapy and 22 (31%) required early treatment discontinuation. Median recurrence-free survival of patients who completed treatment was 22 months (95%CI:15.8-28.2) vs. 9 months (3.3-14.7) if treatment was discontinued early (P<0.001). Median overall survival of those who completed treatment was 33 (17.5-48.5) vs. 16 months (17.5-48.5) with early treatment discontinuation (P<0.001). In the multivariate analysis, treatment discontinuation was significantly correlated with recurrent disease, hazard ratio (HR), 2.57 (1.41-4.68), P = 0.002 and inferior survival, HR, 2.55 (1.39-4.68), P = 0.003. No correlation between treatment timing and survival was noted. CONCLUSIONS: Early discontinuation but not the timing of adjuvant chemotherapy correlates with inferior outcomes.

A framework for role allocation in education, research and leadership services in Canadian academic divisions of general surgery: a modified Delphi consensus.

BACKGROUND: Moving toward a funding standard similar to that for clinical services for roles essential to the functioning of education, research and leadership services within divisions of general surgery is necessary to strengthen divisional resilience. We aimed to identify roles and underlying tasks in these services central to sustainable functioning of Canadian academic divisions of general surgery. METHODS: Between June 2018 and October 2020, we used a 4-step modified Delphi method (online survey, face-to-face nominal group technique [n = 12], semistructured telephone interview [n = 8] and nominal group technique [n = 12]) to achieve national consensus from an expert panel of all 17 heads of academic divisions of general surgery in Canada on the roles and accompanying tasks essential to education, research and leadership services within an academic division of general surgery. We used 70% agreement to determine consensus. RESULTS: The expert panel agreed that a framework for role allocation in education, research and leadership services was relevant and necessary. Consensus was reached for 7 roles within the educational service, 3 roles within the research service and 5 roles within the leadership service. CONCLUSION: Our framework represents a national consensus that defines role standards for education, research and leadership services in Canadian academic divisions of general surgery. The framework can help divisions build resiliency, and enable sustained and deliberate advances in these services.

Early Single-Center Experience With Irreversible Electroporation for Stage 2, 3, and 4 Pancreatic Adenocarcinomas.

OBJECTIVES: Irreversible electroporation (IRE) is an ablation technology that uses electrical energy delivered between electrodes. If the electrodes are placed atraumatically, there is little to no risk of collateral injury, making IRE appealing for the treatment of pancreatic tumors. METHODS: We report on 20 patients with pancreatic adenocarcinoma (PAC) who underwent 21 IRE in our center. There were 6 IRE for stage 2 PAC, 11 for stage 3 PAC, 1 for stage 4 PAC, and 2 patients treated with IRE for recurrence after pancreaticoduodenectomy. One patient had local progression 18 months after IRE and received a second IRE treatment. Using propensity score matching (age, sex, stage, tumor size, and chemotherapy), cases were matched 2 to 1 with patients from the Surveillance, Epidemiology, and End Results database. RESULTS: A total of 7 cases experienced 8 complications; 4 complications were mild, and 4 were severe. Significant survival benefit was seen for patients with stage 3 PAC (27.5 vs 14.6 months for the matched group, P = 0.003); for stage 2, median survival was 15 months, and the single stage 4 patient survived 9 months after IRE treatment. CONCLUSIONS: Pancreatic cancers were safely and effectively treated with image-guided IRE in our medium-sized center.

Rate of Curative Surgery in Real-world Patients with Unresectable Metastatic Colorectal Cancer Treated with FOLFOXIRI ± Bevacizumab: A Western Canadian Province Experience.

BACKGROUND: Recent evidence from randomized trials suggests that FOLFOXIRI (fluorouracil, oxaliplatin, and irinotecan) ± bevacizumab is associated with higher response rates, with the potential for conversion of unresectable to resectable disease in metastatic colorectal cancer (mCRC). However, limited evidence is available on the efficacy and safety of this regimen in real-world patients with mCRC. The current study aims to evaluate the conversion rate and safety of FOLFOXIRI ± bevacizumab in real-world patients with unresectable mCRC. METHODS: In this retrospective multicenter population-based cohort study, patients who were diagnosed with unresectable mCRC between January 2015 and December 2018 in Saskatchewan and received FOLFOXIRI ± bevacizumab were assessed. Kaplan-Meier survival methods and the log-rank test were performed. RESULTS: A total of 28 eligible patients with a median age of 51 years (interquartile range 39-60) and a male:female ratio of 11:17 were identified; 39% had rectal cancer, 46% had extrahepatic disease, and 46% had bilobar liver metastases. Overall, 63% of the patients had a positive response to FOLFOXIRI ± bevacizumab and 53% underwent metastasectomy. Of all patients 60% had grade 3/4 toxicity and 32% required hospital admission. No treatment-related mortality was noted. After 4 years, 50% of the patients were alive. Median progression-free survival of patients who underwent surgery was 18 months (95% CI 11.3-24.7) versus 11 months (4-18.1) without surgery (p = 0.28). Median overall survival of patients with surgery was 33 months (17.5-48.5) versus 16 months (8.3-23.7) without surgery (p = 0.03). CONCLUSION: The current study suggests that FOLFOXIRI ± bevacizumab therapy in real-world patients with mCRC is associated with a high rate of conversion from unresectable to resectable metastatic disease. Patients with metastasectomy had better survival.

Prognosticating Outcome in Pancreatic Head Cancer With the use of a Machine Learning Algorithm.

Background: The purpose of this project is to identify prognostic features in resectable pancreatic head adenocarcinoma and use these features to develop a machine learning algorithm that prognosticates survival for patients pursuing pancreaticoduodenectomy. Methods: A retrospective cohort study of 93 patients who underwent a pancreaticoduodenectomy was performed. The patients were analyzed in 2 groups: Group 1 (n = 38) comprised of patients who survived < 2 years, and Group 2 (n = 55) comprised of patients who survived > 2 years. After comparing the two groups, 9 categorical features and 2 continuous features (11 total) were selected to be statistically significant (p < .05) in predicting outcome after surgery. These 11 features were used to train a machine learning algorithm that prognosticates survival. Results: The algorithm obtained 75% accuracy, 41.9% sensitivity, and 97.5% specificity in predicting whether survival is less than 2 years after surgery. Conclusion: A supervised machine learning algorithm that prognosticates survival can be a useful tool to personalize treatment plans for patients with pancreatic cancer.

Outcomes of Patients with Borderline Resectable Pancreatic Cancer Treated with Combination Chemotherapy.

BACKGROUND: Patients with borderline resectable pancreatic cancer are at high risk of incomplete resection with upfront surgery. Currently, no standard induction chemotherapy regimen exists for these patients. Both FOLFIRINOX (5-FU, irinotecan, & oxaliplatin) and gemcitabine plus nab-paclitaxel (GnP) have shown better efficacy than gemcitabine alone in advanced pancreatic cancer. The current study aims to assess outcomes of real-world patients with borderline resectable pancreatic cancer who received induction FOLFIRINOX or GnP. METHODS: In this population-based multicenter retrospective cohort study, patients with biopsy-proven borderline resectable pancreatic cancer diagnosed from 2011 to 2017, in the province of Saskatchewan, Canada, who received FOLFIRINOX or GnP were assessed. Kaplan Meier methods and log rank tests were performed for survival analyses. RESULTS: Of 161 patients with pancreatic cancer who received FOLFIRINOX or GnP during the study period, 20 eligible patients with borderline resectable pancreatic cancer were identified. Ten patients each received FOLFIRINOX or GnP. Eleven patients had partial response (5, FOLFIRINOX; 6, GnP); 3 progressed during treatment. Five patients (4, FOLFIRINOX; 1, GnP; p = NS) underwent curative surgery. The median progression-free survival was 17 months in FOLFIRINOX (95% CI, 5.3-28.6) vs. 9 months (95% CI, 3.0-15) in GnP groups (p = 0.27). Overall, 80% patients in GnP vs. 40% in FOLFIRINOX died from progressive disease. The median overall survival has not been reached in FOLFIRINOX group versus 16 months (95% CI, 9.3-22.7) in GnP group (p = 0.15). CONCLUSION: The current study suggests that patients with borderline resectable pancreatic cancer who received FOLFIRINOX tend to have better outcomes. Future studies are warranted to establish a preferred systemic therapy for patients with borderline resectable pancreatic cancer.

Second-line Chemotherapy Prolongs Survival in Real World Patients With Advanced Biliary Tract and Gallbladder Cancers: A Multicenter Retrospective Population-based Cohort Study.

BACKGROUND: Limited evidence is available regarding the survival benefit of second-line therapy in real world patients with advanced biliary tract and gallbladder cancer. Until very recently, there was a lack of randomized clinical trials to address this important question. In this multicenter population-based cohort study, the authors evaluated whether second-line therapy improves the survival of real world patients with advanced biliary tract and gallbladder cancer. METHODS: Patients with biopsy-proven advanced biliary tract and gallbladder cancer who were diagnosed during the period of 2006 to 2015 and had received first-line chemotherapy were assessed. Cox proportional multivariate analysis was performed to determine the survival benefit of second-line therapy. RESULTS: One hundred thirty-six eligible patients with a median age of 66 years and male:female ratio of 1:1.34 were identified. Sixty-eight percent of patients had metastatic disease. Primary tumor sites were as follows: gallbladder 31%, intrahepatic cholangiocarcinoma 36%, extrahepatic bile duct 23%, and ampullary cancer 10%. Overall, 37% of patients received second-line therapy. The median overall survival of the treatment group was 17 months (95% confidence interval [CI]: 12.5-21.5) compared with 7 months (95% CI: 5.3-8.7) in the control (P<0.0001). Patients who received combination chemotherapy had a median overall survival of 20 months (14.0-26.1) compared with 17 months (13.5-20.5) if they received single-agent second-line therapy (P=0.73). Multivariate analysis of second-line therapy, hazard ratio: 0.55 (95% CI: 0.36-0.83) and neutrophil to lymphocyte ratio >2, HR: 1.10 (1.05-1.15) showed a significant correlation with survival. CONCLUSIONS: This well-designed population-based retrospective cohort study suggests that second-line chemotherapy improves survival of real world patients with advanced biliary tract and gallbladder cancers and should be offered to the patients who are potential candidates for chemotherapy.

Comparisons of Outcomes of Real-World Patients With Advanced Pancreatic Cancer Treated With FOLFIRINOX Versus Gemcitabine and Nab-Paclitaxel: A Population-Based Cohort Study.

OBJECTIVES: The aim of this study was to compare the efficacy and safety of FOLFIRINOX (5-FU/leucovorin, irinotecan, and oxaliplatin) and gemcitabine/nab-paclitaxel (GnP) in patients with advanced pancreatic cancer. METHODS: Patients with newly diagnosed advanced pancreatic cancer in Saskatchewan, Canada, from 2011 to 2016, who received FOLFIRINOX or GnP were assessed. A Cox proportional multivariate analysis was performed to evaluate prognostic variables. RESULTS: One hundred nineteen eligible patients with median age of 61 years and male/female ratio of 70:49 were identified. Seventy-seven percent had metastatic disease. Of 119 patients, 86 (72%) received FOLFIRINOX and 33 (28%) were treated with GnP. Median progression-free survival of the FOLFIRINOX group was 6.0 months [95% confidence interval (CI), 4.5-7.5] versus 4.0 months (95% CI, 2.9-5.1) with GnP (P = 0.39). The median overall survival of the FOLFIRINOX group was 9.0 months (95% CI, 7-11) compared with 9.0 months (95% CI, 4.2-13.8) with GnP (P = 0.88). On multivariate analysis, albumin [hazard ratio (HR), 0.63; 95% CI, 0.41-0.97], male sex (HR, 0.65; 95% CI, 0.43-0.97), and second-line therapy (HR, 0.50; 95% CI, 0.28-0.86) were correlated with survival. CONCLUSIONS: Our results showed that real-world patients with advanced pancreatic cancer treated with FOLFIIRNOX or GnP had comparable survival with different safety profile.

Multiseed liposomal drug delivery system using micelle gradient as driving force to improve amphiphilic drug retention and its anti-tumor efficacy.

To improve drug retention in carriers for amphiphilic asulacrine (ASL), a novel active loading method using micelle gradient was developed to fabricate the ASL-loaded multiseed liposomes (ASL-ML). The empty ML were prepared by hydrating a thin film with empty micelles. Then the micelles in liposomal compartment acting as 'micelle pool' drove the drug to be loaded after the outer micelles were removed. Some reasoning studies including critical micelle concentration (CMC) determination, influencing factors tests on entrapment efficiency (EE), structure visualization, and drug release were carried out to explore the mechanism of active loading, ASL location, and the structure of ASL-ML. Comparisons were made between pre-loading and active loading method. Finally, the extended drug retention capacity of ML was evaluated through pharmacokinetic, drug tissue irritancy, and in vivo anti-tumor activity studies. Comprehensive results from fluorescent and transmission electron microscope (TEM) observation, encapsulation efficiency (EE) comparison, and release studies demonstrated the formation of ML-shell structure for ASL-ML without inter-carrier fusion. The location of drug mainly in inner micelles as well as the superiority of post-loading to the pre-loading method , in which drug in micelles shifted onto the bilayer membrane was an additional positive of this delivery system. It was observed that the drug amphiphilicity and interaction of micelles with drug were the two prerequisites for this active loading method. The extended retention capacity of ML has been verified through the prolonged half-life, reduced paw-lick responses in rats, and enhanced tumor inhibition in model mice. In conclusion, ASL-ML prepared by active loading method can effectively load drug into micelles with expected structure and improve drug retention.

Optimization of Weight Ratio for DSPE-PEG/TPGS Hybrid Micelles to Improve Drug Retention and Tumor Penetration.

PURPOSE: To enhance therapeutic efficacy and prevent phlebitis caused by Asulacrine (ASL) precipitation post intravenous injection, ASL-loaded hybrid micelles with size below 40 nm were developed to improve drug retention and tumor penetration. METHODS: ASL-micelles were prepared using different weight ratios of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-polyethyleneglycol-2000 (DSPE-PEG2000) and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) polymers. Stability of micelles was optimized in terms of critical micelle concentration (CMC) and drug release properties. The encapsulation efficiency (EE) and drug loading were determined using an established dialysis-mathematic fitting method. Multicellular spheroids (MCTS) penetration and cytotoxicity were investigated on MCF-7 cell line. Pharmacokinetics of ASL-micelles was evaluated in rats with ASL-solution as control. RESULTS: The ASL-micelles prepared with DSPE-PEG2000 and TPGS (1:1, w/w) exhibited small size (~18.5 nm), higher EE (~94.12%), better sustained in vitro drug release with lower CMC which may be ascribed to the interaction between drug and carriers. Compared to free ASL, ASL-micelles showed better MCTS penetration capacity and more potent cytotoxicity. Pharmacokinetic studies demonstrated that the half-life and AUC values of ASL-micelles were approximately 1.37-fold and 3.49-fold greater than that of free ASL. CONCLUSIONS: The optimized DSPE-PEG2000/TPGS micelles could serve as a promising vehicle to improve drug retention and penetration in tumor.

The E3 ubiquitin ligase NEDD4 is an LC3-interactive protein and regulates autophagy.

The MAP1LC3/LC3 family plays an essential role in autophagosomal biogenesis and transport. In this report, we show that the HECT family E3 ubiquitin ligase NEDD4 interacts with LC3 and is involved in autophagosomal biogenesis. NEDD4 binds to LC3 through a conserved WXXL LC3-binding motif in a region between the C2 and the WW2 domains. Knockdown of NEDD4 impaired starvation- or rapamycin-induced activation of autophagy and autophagosomal biogenesis and caused aggregates of the LC3 puncta colocalized with endoplasmic reticulum membrane markers. Electron microscopy observed gigantic deformed mitochondria in NEDD4 knockdown cells, suggesting that NEDD4 might function in mitophagy. Furthermore, SQSTM1 is ubiquitinated by NEDD4 while LC3 functions as an activator of NEDD4 ligase activity. Taken together, our studies define an important role of NEDD4 in regulation of autophagy.

A simulator-based nuclear reactor emergency response training exercise.

Training offsite emergency response personnel basic awareness of onsite control room operations during nuclear power plant emergency conditions was the primary objective of a week-long workshop conducted on a CANDU® virtual nuclear reactor simulator available at the University of Ontario Institute of Technology, Oshawa, Canada. The workshop was designed to examine both normal and abnormal reactor operating conditions, and to observe the conditions in the control room that may have impact on the subsequent offsite emergency response. The workshop was attended by participants from a number of countries encompassing diverse job functions related to nuclear emergency response. Objectives of the workshop were to provide opportunities for participants to act in the roles of control room personnel under different reactor operating scenarios, providing a unique experience for participants to interact with the simulator in real-time, and providing increased awareness of control room operations during accident conditions. The ability to "pause" the simulator during exercises allowed the instructors to evaluate and critique the performance of participants, and to provide context with respect to potential offsite emergency actions. Feedback from the participants highlighted (i) advantages of observing and participating "hands-on" with operational exercises, (ii) their general unfamiliarity with control room operational procedures and arrangements prior to the workshop, (iii) awareness of the vast quantity of detailed control room procedures for both normal and transient conditions, and (iv) appreciation of the increased workload for the operators in the control room during a transient from normal operations. Based upon participant feedback, it was determined that the objectives of the training had been met, and that future workshops should be conducted.

Optimization of the formation of embedded multicellular spheroids of MCF-7 cells: How to reliably produce a biomimetic 3D model.

To obtain a multicellular MCF-7 spheroid model to mimic the three-dimensional (3D) of tumors, the microwell liquid overlay (A) and hanging-drop/agar (B) methods were first compared for their technical parameters. Then a method for embedding spheroids within collagen was optimized. For method A, centrifugation assisted cells form irregular aggregates but not spheroids. For method B, an extended sedimentation period of over 24 h for cell suspensions and increased viscosity of the culture medium using methylcellulose were necessary to harvest a dense and regular cell spheroid. When the number was less than 5000 cells/drop, embedded spheroids showed no tight cores and higher viability than the unembedded. However, above 5000 cells/drop, cellular viability of embedded spheroids was not significantly different from unembedded spheroids and cells invading through the collagen were in a sun-burst pattern with tight cores. Propidium Iodide staining indicated that spheroids had necrotic cores. The doxorubicin cytotoxicity demonstrated that spheroids were less susceptible to DOX than their monolayer cells. A reliable and reproducible method for embedding spheroids using the hanging-drop/agarose method within collagen is described herein. The cell culture model can be used to guide experimental manipulation of 3D cell cultures and to evaluate anticancer drug efficacy.

Improving drug retention in liposomes by aging with the aid of glucose.

This paper describes a novel method to improve drug retention in liposomes for the poorly water-soluble (lipophilic) model drug asulacrine (ASL). ASL was loaded in the aqueous phase of liposomes and the effects of aging conditions and drug loading levels on drug retention were investigated using an in vitro bio-relevant drug release test established in this study. The status of intra-liposomal drug was investigated using differential scanning calorimetry (DSC) and cryo-transmission electron microscopy (cryo-TEM). Pharmacokinetics and venous tolerance of the formulations were simultaneously studied in rabbits following one-hour intravenous infusion via the ear vein. The presence of glucose during aging was found to be crucial to accelerate drug precipitation and to stabilize the liposomal membrane with high drug loading (8.9% over 4.5% w/w) as a prerequisite. Although no drug crystals were detected, DSC showed a lower phase-transition peak in the glucose-assisted aged ASL-liposomes, indicating interaction of phospholipids with the sugar. Cryo-TEM revealed more 'coffee bean' like drug precipitate in the ASL-liposomes aged in the glucose solution. In rabbits, these liposomes gave rise to a 1.9 times longer half-life than the fresh liposomes, with no venous irritation observed. Inducing and stabilizing drug precipitation in the liposome cores by aging in the presence of sugar provided an easy approach to improve drug retention in liposomes. The study also highlighted the importance of bio-relevance of in vitro release methods to predict in vivo drug release.

Post-insertion of poloxamer 188 strengthened liposomal membrane and reduced drug irritancy and in vivo precipitation, superior to PEGylation.

The ultimate aim of this study was to develop asulacrine (ASL)-loaded long-circulating liposomes to prevent phlebitis during intravenous (i.v.) infusion for chemotherapy. Poly(ethylene)glycol (PEG) and poloxamer 188-modified liposomes (ASL-PEGL and ASL-P188L) were developed, and ASL was loaded using a remote loading method facilitated with a low concentration of sulfobutyl ether-ß-cyclodextrin as a drug solubilizer. The liposomes were characterized in terms of morphology, size, release properties and stability. Pharmacokinetics and venous tissue tolerance of the formulations were simultaneously studied in rabbits following one-hour i.v. infusion via the ear vein. The irritancy was assessed using a rat paw-lift/lick model after subplantar injections. High drug loading 9.0% w/w was achieved with no drug leakage found from ASL-PEGL or ASL-P188L suspended in a 5% glucose solution at 30days. However, a rapid release (leakage) from ASL-PEGL was observed when PBS was used as release medium, partially related to the use of cyclodextrin in drug loading. Post-insertion of poloxamer 188 to the liposomes appeared to be able to restore the drug retention possibly by increasing the packing density of phospholipids in the membrane. In rabbits (n=5), ASL-P188L had a prolonged half-life with no drug precipitation or inflammation in the rabbit ear vein in contrast to ASL solution. Following subplantar (footpad) injections in rats ASL solution induced paw-lick/lift responses in all rats whereas ASL-P188L caused no response (n=8). PEGylation showed less benefit possibly due to the drug 'leakage'. In conclusion, drug precipitation in the vein and the drug mild irritancy may both contribute to the occurrence of phlebitis caused by the ASL solution, and could both be prevented by encapsulation of the drug in liposomes. Poloxamer 188 appeared to be able to 'seal' the liposomal membrane and enhance drug retention. The study also highlighted the importance of bio-relevant in vitro release study in formulation screening.

Strategies to maximize liposomal drug loading for a poorly water-soluble anticancer drug.

PURPOSE: To develop a liposomal system with high drug loading (DL) for intravenous (i.v.) delivery of a poorly water-soluble basic drug, asulacrine (ASL). METHODS: A thin-film hydration and extrusion method was used to fabricate the PEGylated liposomal membranes followed by a freeze and thaw process. A novel active drug loading method was developed using ammonium sulphate gradient as an influx driving force of ASL solubilized with sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD). DL was maximized by optimizing liposomal preparation and loading conditions. Pharmacokinetics was evaluated following i.v. infusion in rabbits. RESULTS: Freeze-thaw resulted in unilamellar liposome formation (180 nm) free of micelles. Higher DL was obtained when dialysis was used to remove the untrapped ammonium sulphate compared to ultracentrifuge. The pH and SBE-ß-CD level in the loading solution played key roles in enhancing DL. High DL ASL-liposomes (8.9%w/w, drug-to-lipid mole ratio 26%) were obtained with some drug "bundles" in the liposomal cores and were stable in a 5% glucose solution for >80 days with minimal leakage (<2%). Surprisingly, following administration of ASL-liposomes prepared with or without SBE-ß-CD, the half-lives were similar to the drug solution despite an increased area under the curve, indicating drug leakage from the carriers. CONCLUSIONS: High liposomal DL was achieved with multiple strategies for a poorly-water soluble weak base. However, the liposomal permeability needed to be tailored to improve drug retention.

Physicochemical characterization of asulacrine towards the development of an anticancer liposomal formulation via active drug loading: stability, solubility, lipophilicity and ionization.

To facilitate the development of a liposomal formulation for cancer therapy, the physicochemical properties of asulacrine (ASL), an anticancer drug candidate, were characterized. Nano-liposomes were prepared by thin-film hydration in conjugation with active drug loading using ammonium sulphate and post-insertion with Poloxamer 188. A stability-indicating HPLC assay with diode array detection was developed for the determination of ASL concentrations. The U-shaped pH-solubility profile in aqueous solutions, with a lowest solubility at pH 7.4 (0.843 µg/mL), indicated that ASL is an ampholyte, and dilution or neutralization of acidic drug solutions used in clinical trials with physiological fluids may cause drug precipitation. The basic pKa value measured by absorbance spectroscopy was 6.72. The logD value at pH 3.8 was 1.15 which increased to 3.24 as pH increased to 7.4. ASL was found to be the most stable in acidic conditions and degraded most rapidly in alkaline conditions. An extra-liposomal pH of 5.6 during drug loading was found to be optimal to achieve the highest drug loading (DL) of 4.76% and entrapment efficiency (EE) of 99.9%. At this pH, >90% of ASL was ionized conferring high drug solubility (1mg/mL) and acted as a reservoir of unionized ASL to be transported into liposomal cores. As a suspension the optimized liposomes showed great physicochemical stability for five months at 4°C. In summary, the obtained physicochemical parameters provided insightful information useful to maximise DL into the liposomes, and explain a tendency of drug precipitation of pH-solubilized formulations following intravenous infusion.