Pharmaceutical Research (v.34, #10)
Reflections on the Future of Pharmaceutical Public-Private Partnerships: From Input to Impact by Remco L. A. de Vrueh; Daan J. A. Crommelin (1985-1999).
Public Private Partnerships (PPPs) are multiple stakeholder partnerships designed to improve research efficacy. We focus on PPPs in the biomedical/pharmaceutical field, which emerged as a logical result of the open innovation model. Originally, a typical PPP was based on an academic and an industrial pillar, with governmental or other third party funding as an incentive. Over time, other players joined in, often health foundations, patient organizations, and regulatory scientists. This review discusses reasons for initiating a PPP, focusing on precompetitive research. It looks at typical expectations and challenges when starting such an endeavor, the characteristics of PPPs, and approaches to assessing the success of the concept. Finally, four case studies are presented, of PPPs differing in size, geographical spread, and research focus.
Keywords: key drivers; performance evaluation; public-private-partnerships; R&D business models
Optimizing the Bioavailability of Subcutaneously Administered Biotherapeutics Through Mechanochemical Drivers by D. S. Collins; L. C. Kourtis; N. R. Thyagarajapuram; R. Sirkar; S. Kapur; M. W. Harrison; D. J. Bryan; G. B. Jones; J. M. Wright (2000-2011).
The subcutaneous route offers myriad benefits for the administration of biotherapeutics in both acute and chronic diseases, including convenience, cost effectiveness and the potential for automation through closed-loop systems. Recent advances in parenteral administration devices and the use of additives which enhance drug dispersion have generated substantial additional interest in IV to SQ switching studies. Designing pre-clinical and clinical studies using SQ mediated delivery however requires deep understanding of complex inter-related physiologies and transport pathways governing the interstitial matrix, vascular system and lymphatic channels. This expert review will highlight key structural features which contribute to transport and biodistribution in the subcutaneous space and also assess the impact of drug formulations. Based on the rapidly growing interest in the SQ delivery route, a number of potential areas for future development are highlighted, which are likely to allow continued evolution and innovation in this important area.
Keywords: biodistribution; biologics; drug delivery; lymphatics; subcutaneous
Scanning Electron Microscope Observations of Powder Sticking on Punches during a Limited Number (N < 5) of Compactions of Acetylsalicylic Acid by Henrietta Tsosie; James Thomas; John Strong; Antonios Zavaliangos (2012-2024).
To obtain quantitative information and mechanistic insight into the problem of sticking of acetylsalicylic acid tablets on a metallic punch.Low voltage scanning electron microscopy was used to observe punch area coverage and morphology of adhered powder on a flat punch used for a limited number of compactions.Material accumulation in terms of area coverage of the punch per compaction cycle was determined at two pressures over five compactions. The distribution of the adhered material on the punch was non-uniform with more material left on the center of the punch. The sizes of the adhered particles range from 1 to 100 μm, with 50% of the punch surface coverage from particles of an equivalent diameter > 30 μm. Three types of adhered particles were identified after the first compaction: (a) fragments of initial particles with very high aspect ratio, (b) nearly equiaxed fragments with multiple cracks, (c) heavily deformed islands of low profile. Some preliminary ideas that explain these observations are presented and discussed.The ability of SEM to provide quantitative information on sticking from few compactions presents an interesting possibility for a material sparing technique that provides insight on the propensity of sticking.
Keywords: acetylsalicylic acid; scanning electron microscopy; sticking
Drug Delivery Nanoparticles with Locally Tunable Toxicity Made Entirely from a Light-Activatable Prodrug of Doxorubicin by Carolyn Schutt; Stuart Ibsen; Eran Zahavy; Santosh Aryal; Stacey Kuo; Selin Esener; Michael Berns; Sadik Esener (2025-2035).
A major challenge facing nanoparticle-based delivery of chemotherapy agents is the natural and unavoidable accumulation of these particles in healthy tissue resulting in local toxicity and dose-limiting side effects. To address this issue, we have designed and characterized a new prodrug nanoparticle with controllable toxicity allowing a locally-delivered light trigger to convert the payload of the particle from a low to a high toxicity state.The nanoparticles are created entirely from light-activatable prodrug molecules using a nanoprecipitation process. The prodrug is a conjugate of doxorubicin and photocleavable biotin (DOX-PCB).These DOX-PCB nanoparticles are 30 times less toxic to cells than doxorubicin, but can be activated to release pure therapeutic doxorubicin when exposed to 365 nm light. These nanoparticles have an average diameter of around 100 nm and achieve the maximum possible prodrug loading capacity since no support structure or coating is required to prevent loss of prodrug from the nanoparticle.These light activatable nanoparticles demonstrate tunable toxicity and can be used to facilitate future therapy development whereby light delivered specifically to the tumor tissue would locally convert the nanoparticles to doxorubicin while leaving nanoparticles accumulated in healthy tissue in the less toxic prodrug form.
Keywords: DNA intercalation; Doxorubicin; Light-activatable; Nanoparticle drug delivery vehicle; Prodrug
Development of a Two-Dimensional Model for Predicting Transdermal Permeation with the Follicular Pathway: Demonstration with a Caffeine Study by Panayiotis Kattou; Guoping Lian; Stephen Glavin; Ian Sorrell; Tao Chen (2036-2048).
The development of a new two-dimensional (2D) model to predict follicular permeation, with integration into a recently reported multi-scale model of transdermal permeation is presented.The follicular pathway is modelled by diffusion in sebum. The mass transfer and partition properties of solutes in lipid, corneocytes, viable dermis, dermis and systemic circulation are calculated as reported previously [Pharm Res 33 (2016) 1602]. The mass transfer and partition properties in sebum are collected from existing literature. None of the model input parameters was fit to the clinical data with which the model prediction is compared.The integrated model has been applied to predict the published clinical data of transdermal permeation of caffeine. The relative importance of the follicular pathway is analysed. Good agreement of the model prediction with the clinical data has been obtained. The simulation confirms that for caffeine the follicular route is important; the maximum bioavailable concentration of caffeine in systemic circulation with open hair follicles is predicted to be 20% higher than that when hair follicles are blocked.The follicular pathway contributes to not only short time fast penetration, but also the overall systemic bioavailability. With such in silico model, useful information can be obtained for caffeine disposition and localised delivery in lipid, corneocytes, viable dermis, dermis and the hair follicle. Such detailed information is difficult to obtain experimentally.
Keywords: bioavailability; diffusion; in silico modelling; pharmacokinetic model; transdermal drug delivery
Small Airway Absorption and Microdosimetry of Inhaled Corticosteroid Particles after Deposition by P. Worth Longest; Michael Hindle (2049-2065).
To predict the cellular-level epithelial absorbed dose from deposited inhaled corticosteroid (ICS) particles in a model of an expanding and contracting small airway segment for different particle forms.A computational fluid dynamics (CFD)-based model of drug dissolution, absorption and clearance occurring in the surface liquid of a representative small airway generation (G13) was developed and used to evaluate epithelial dose for the same deposited drug mass of conventional microparticles, nanoaggregates and a true nanoaerosol. The ICS medications considered were budesonide (BD) and fluticasone propionate (FP). Within G13, total epithelial absorption efficiency (AE) and dose uniformity (microdosimetry) were evaluated.Conventional microparticles resulted in very poor AE of FP (0.37%) and highly nonuniform epithelial absorption, such that <5% of cells received drug. Nanoaggregates improved AE of FP by a factor of 57-fold and improved dose delivery to reach approximately 40% of epithelial cells. True nanoaerosol resulted in near 100% AE for both drugs and more uniform drug delivery to all cells.Current ICS therapies are absorbed by respiratory epithelial cells in a highly nonuniform manner that may partially explain poor clinical performance in the small airways. Both nanoaggregates and nanoaerosols can significantly improve ICS absorption efficiency and uniformity.
Keywords: Asthma; Computational fluid dynamics; Nanoaerosol; Nanoaggregate; Pharmaceutical aerosols
Computational Analysis on Down-Regulated Images of Macrophage Scavenger Receptor by Byeongtaek Oh; Yugyung Lee; Mingui Fu; Chi H. Lee (2066-2074).
Thiolated-graphene quantum dots (SH-GQDs) were developed and assessed for an efficient preventive means against atherosclerosis and potential toxicity through computational image analysis and animal model studies.Zebrafish (wild-type, wt) were used for evaluation of toxicity through the assessment of embryonic mortality, malformation and ROS generation. The amounts of SH-GQDs uptaken by mouse macrophage cells (Raw264.7) were analyzed using a flow cytometer. For the time-dependent cellular uptake study, Raw264.7 cells were treated with SH-GQDs (200 μg/ml) at specific time intervals (0.5, 1, 2, 5, 10 and 24 h). The efficacy of SH-GQDs on DiO-oxLDL efflux by Raw264.7 cells was evaluated (DiO, 3,3′-dioctadecyl-oxacarbocyanine) based on the percentage of positive cells containing DiO-oxLDL. TEER of human primary umbilical vein endothelial cells (hUVECs) were examined to assess the barrier function of the cell layers upon being treated with oxLDL.SH-GQDs significantly enhanced the efflux of oxLDL and down-regulated macrophage scavenger receptor (MSR) in Raw264.7. The ROS levels stimulated by oxidative stress were alleviated by SH-GQDs. oxLDL (10 μg/ml) significantly impaired the barrier function (TEER) of adherence junctions, which was recovered by SH-GQDs (10 μg/ml) (oxLDL: 67.2 ± 2.2 Ω-cm2 for 24 h; SH-GQDs: 114.6 ± 8.5 Ω-cm2 for 24 h). The mortality rate (46% for 1 mg/ml) of the zebra fish increased, as the concentrations and exposure duration of SH-GQDs increased. SH-GQDs exerted negligible side effects.SH-GQDs have target specificity to macrophage scavenger receptor (MSR) and efficiently recovered the ROS levels and TEER. SH-GQDs did not induce endothelial cell layer disruption nor affected zebrafish larvae survival.
Keywords: macrophage scavenger receptor (MSR); oxLDL; theranostic carrier; thiolated-graphene quantum dots (SH-GQDs)
Gentamicin-Loaded Polysaccharide Membranes for Prevention and Treatment of Post-operative Wound Infections in the Skeletal System by Urszula Cibor; Małgorzata Krok-Borkowicz; Monika Brzychczy-Włoch; Łucja Rumian; Krzysztof Pietryga; Dominika Kulig; Wojciech Chrzanowski; Elżbieta Pamuła (2075-2083).
To develop polysaccharide-based membranes that allow controlled and localized delivery of gentamicin for the treatment of post-operative bone infections.Membranes made of gellan gum (GUM), sodium alginate (ALG), GUM and ALG crosslinked with calcium ions (GUM + Ca and ALG + Ca, respectively) as well as reference collagen (COL) were produced by freeze-drying. Mechanical properties, drug release, antimicrobial activity and cytocompatibility of the membranes were assessed.The most appropriate handling and mechanical properties (Young’s modulus, E = 92 ± 4 MPa and breaking force, F MAX = 2.6 ± 0.1 N) had GUM + Ca membrane. In contrast, COL membrane showed F MAX = 0.14 ± 0.02 N, E = 1.0 ± 0.3 MPa and was deemed to be unsuitable for antibiotic delivery. The pharmacokinetic data demonstrated a uniform and sustainable delivery of gentamicin from GUM + Ca (44.4 ± 1.3% within 3 weeks), while for COL, ALG and ALG + Ca membranes the most of the drug was released within 24 h (55.3 ± 1.9%, 52.5 ± 1.5% and 37.5 ± 1.8%, respectively). Antimicrobial activity against S. aureus and S. epidermidis was confirmed for all the membranes. GUM + Ca and COL membranes supported osteoblasts growth, whereas on ALG and ALG + Ca membranes cell growth was reduced.GUM + Ca membrane holds promise for effective treatment of bone infections thanks to favorable pharmacokinetics, bactericidal activity, cytocompatibility and good mechanical properties.
Keywords: alginate; gellan gum; gentamicin; local drug delivery; membranes
Anti-Tuberculosis Bacteriophage D29 Delivery with a Vibrating Mesh Nebulizer, Jet Nebulizer, and Soft Mist Inhaler by Nicholas B. Carrigy; Rachel Y. Chang; Sharon S. Y. Leung; Melissa Harrison; Zaritza Petrova; Welkin H. Pope; Graham F. Hatfull; Warwick J. Britton; Hak-Kim Chan; Dominic Sauvageau; Warren H. Finlay; Reinhard Vehring (2084-2096).
To compare titer reduction and delivery rate of active anti-tuberculosis bacteriophage (phage) D29 with three inhalation devices.Phage D29 lysate was amplified to a titer of 11.8 ± 0.3 log10(pfu/mL) and diluted 1:100 in isotonic saline. Filters captured the aerosolized saline D29 preparation emitted from three types of inhalation devices: 1) vibrating mesh nebulizer; 2) jet nebulizer; 3) soft mist inhaler. Full-plate plaque assays, performed in triplicate at multiple dilution levels with the surrogate host Mycobacterium smegmatis, were used to quantify phage titer. Respective titer reductions for the vibrating mesh nebulizer, jet nebulizer, and soft mist inhaler were 0.4 ± 0.1, 3.7 ± 0.1, and 0.6 ± 0.3 log10(pfu/mL). Active phage delivery rate was significantly greater (p < 0.01) for the vibrating mesh nebulizer (3.3x108 ± 0.8x108 pfu/min) than for the jet nebulizer (5.4x104 ± 1.3x104 pfu/min). The soft mist inhaler delivered 4.6x106 ± 2.0x106 pfu per 11.6 ± 1.6 μL ex-actuator dose.Delivering active phage requires a prudent choice of inhalation device. The jet nebulizer was not a good choice for aerosolizing phage D29 under the tested conditions, due to substantial titer reduction likely occurring during droplet production. The vibrating mesh nebulizer is recommended for animal inhalation studies requiring large amounts of D29 aerosol, whereas the soft mist inhaler may be useful for self-administration of D29 aerosol.
Keywords: aerosol; Mycobacterium tuberculosis ; nebulization; phage therapy; titer reduction
Galactosyl Pentadecene Reversibly Enhances Transdermal and Topical Drug Delivery by Monika Kopečná; Miloslav Macháček; Eva Prchalová; Petr Štěpánek; Pavel Drašar; Martin Kotora; Kateřina Vávrová (2097-2108).
To study new skin penetration/permeation enhancers based on amphiphilic galactose derivatives.Two series of alkyl and alkenyl galactosides were synthesized and evaluated for their enhancing effect on transdermal/topical delivery of theophylline (TH), hydrocortisone (HC) and cidofovir (CDV), reversibility of their effects on transepidermal water loss (TEWL) and skin impedance, interaction with the stratum corneum using infrared spectroscopy, and cytotoxicity on keratinocytes and fibroblasts.Initial evaluation identified 1-(α-d-galactopyranosyl)-(2E)-pentadec-2-ene A15 as a highly potent enhancer – it increased TH and HC flux through human skin 8.5 and 5 times, respectively. Compound A15 increased the epidermal concentration of a potent antiviral CDV 7 times over that reached by control and Span 20 (an established sugar-based enhancer). Infrared spectroscopy of human stratum corneum indicated interaction of A15 with skin barrier lipids but not proteins. These effects of A15 on the skin barrier were reversible (both TEWL and skin impedance returned to baseline values within 24 h after A15 had been removed from skin). In vitro toxicity of A15 on HaCaT keratinocytes and 3T3 fibroblasts was acceptable, with IC50 values over 60 μM.Galactosyl pentadecene A15 is a potent enhancer with low toxicity and reversible action.
Keywords: galactoside; penetration enhancers; sugar; topical drug delivery; transdermal drug delivery
Item Response Theory as an Efficient Tool to Describe a Heterogeneous Clinical Rating Scale in De Novo Idiopathic Parkinson’s Disease Patients by Simon Buatois; Sylvie Retout; Nicolas Frey; Sebastian Ueckert (2109-2118).
This manuscript aims to precisely describe the natural disease progression of Parkinson’s disease (PD) patients and evaluate approaches to increase the drug effect detection power.An item response theory (IRT) longitudinal model was built to describe the natural disease progression of 423 de novo PD patients followed during 48 months while taking into account the heterogeneous nature of the MDS-UPDRS. Clinical trial simulations were then used to compare drug effect detection power from IRT and sum of item scores based analysis under different analysis endpoints and drug effects.The IRT longitudinal model accurately describes the evolution of patients with and without PD medications while estimating different progression rates for the subscales. When comparing analysis methods, the IRT-based one consistently provided the highest power.IRT is a powerful tool which enables to capture the heterogeneous nature of the MDS-UPDRS.
Keywords: drug effect; item response theory; MDS-UPDRS; Parkinson’s disease; pharmacometrics
Individual Bayesian Information Matrix for Predicting Estimation Error and Shrinkage of Individual Parameters Accounting for Data Below the Limit of Quantification by Thi Huyen Tram Nguyen; Thu Thuy Nguyen; France Mentré (2119-2130).
In mixed models, the relative standard errors (RSE) and shrinkage of individual parameters can be predicted from the individual Bayesian information matrix (MBF). We proposed an approach accounting for data below the limit of quantification (LOQ) in MBF.MBF is the sum of the expectation of the individual Fisher information (MIF) which can be evaluated by First-Order linearization and the inverse of random effect variance. We expressed the individual information as a weighted sum of predicted MIF for every possible design composing of measurements above and/or below LOQ. When evaluating MIF, we derived the likelihood expressed as the product of the likelihood of observed data and the probability for data to be below LOQ. The relevance of RSE and shrinkage predicted by MBF in absence or presence of data below LOQ were evaluated by simulations, using a pharmacokinetic/viral kinetic model defined by differential equations.Simulations showed good agreement between predicted and observed RSE and shrinkage in absence or presence of data below LOQ. We found that RSE and shrinkage increased with sparser designs and with data below LOQ.The proposed method based on MBF adequately predicted individual RSE and shrinkage, allowing for evaluation of a large number of scenarios without extensive simulations.
Keywords: Bayesian fisher information matrix; data below the limit of quantification; nonlinear mixed effect models; optimal design; shrinkage
Influence of Molecular size on the clearance of antibody fragments by Zhe Li; Ben-Fillippo Krippendorff; Dhaval K. Shah (2131-2141).
To establish a continuous relationship between the size of various antibody fragments and their systemic clearance (CL) in mice.Two different orthogonal approaches have been used to establish the relationship. First approach uses CL values estimated by non-compartmental analysis (NCA) to establish a correlation with protein size. The second approach simultaneously characterizes the PK data for all the proteins using a 2-compartment model to establish a relationship between protein size and pharmacokinetic (PK) parameters.Simple mathematical functions (e.g. sigmoidal, power law) were able to characterize the CL vs. protein size relationship generated using the investigated proteins. The relationship established in mouse was used to predict rat, rabbit, monkey, and human relationships using allometric scaling. The predicted relationships were found to capture the available spares data from each species reasonably well.The CL vs. protein size relationship is important for establishing a robust quantitative structure-PK relationship (QSPKR) for protein therapeutics. The relationship presented here can help in a priori predicting plasma exposure of therapeutic proteins, and together with our previously established relationship between plasma and tissue concentrations of proteins, it can predict the tissue exposure of non-binding proteins simply based on molecular weight/radius and dose.
Keywords: Antibody Fragments; Compartmental Modeling; Monoclonal Antibody (mAb); QSPKR; Systemic Clearance
Evaluation of the Crystallization Tendency of Commercially Available Amorphous Tacrolimus Formulations Exposed to Different Stress Conditions by Niraj S. Trasi; Hitesh S. Purohit; Lynne S. Taylor (2142-2155).
Tacrolimus, an immunosuppressant, is a poorly water soluble compound whereby the commercially available capsule formulations contain the drug in amorphous form. The goal of this study was to evaluate the robustness of the innovator product and five generic formulations to crystallization following storage at stress conditions.Products were purchased from a pharmacy and stored at 40°C/75% relative humidity (RH), open dish conditions. Crystallinity was determined using X-ray diffraction. The quantity of the ingredients in the formulations were determined using different approaches and the various factors that might cause instability in the formulations were studied.After 4 weeks of open dish storage at 40°C/75% RH, one of the generic formulations showed evidence of tacrolimus crystallization. Further investigations revealed batch-to-batch variations in crystallization tendency with the extent of crystallinity varying between 50 and 100% for different batches. Crystallization was also observed at lower storage temperatures (30°C) when the RH was maintained at 75%. It was found that crystallization could be induced in a model formulation by wet granulating an ethanolic solution of the drug with lactose and drying at 60–70°C followed by exposure to stress conditions.It seems probable that the generic that was susceptible to crystallization contains amorphous drug physically mixed with polymeric excipients, rather than as an amorphous solid dispersion. This study highlights the importance of considering the manufacturing process on the stability of the resultant amorphous product.
Keywords: amorphous; crystallization; generic; stability; tacrolimus
Hemodynamic Effects of Lipid-Based Oxygen Microbubbles via Rapid Intravenous Injection in Rodents by Katherine J. Black; Andrew T. Lock; Lindsay M. Thomson; Alexis R. Cole; Xiaoqi Tang; Brian D. Polizzotti; John N. Kheir (2156-2162).
Low oxygen levels, or hypoxemia, is a common cause of morbidity and mortality in critically ill patients. Hypoxemia is typically addressed by increasing the fraction of inspired oxygen, the use of mechanical ventilation, or more invasive measures. Recently, the injection of oxygen gas directly into the bloodstream by packaging it within lipid-based oxygen microbubbles (LOMs) has been explored. The purpose of this work is to examine the acute hemodynamic effects of intravenous injections of LOMs.LOMs composed of 1,2-distearoyl-sn-glycero-3-phosphocoline and cholesterol were manufactured using a process of shear homogenization under an oxygen headspace. A 5 mL aliquot of either PlasmaLyte A, or low (37%) or high (55%) concentration LOMs (n = 10 per group) was injected over a 1 min period into Sprague Dawley rats instrumented for measurement of cardiac index and pulmonary (PVR) and systemic (SVR) vascular resistance during a 60 min observation period. Hemodynamics were compared between groups by linear mixed modeling.Approximately 1011 LOMs with mean diameter 3.77 ± 1.19 μm were injected over the 1 min period. Relative to controls, rodents treated with high concentration LOMs exhibited a higher pulmonary artery pressure (20 ± 0.4 mmHg vs 18 ± 0.4 mmHg, P < 0.001) and higher PVR (0.31 ± 0.01 vs 0.23 ± 0.01 mmHg/mL*min*kg, P < 0.001. Despite a stable cardiac index (62.2 ± 3.5 vs 62.3 ± 3.4 mL/min*kg, P < 0.001), mean arterial blood pressure decreased significantly in LOM-treated animals (46 ± 2 vs 60 ± 2 mmHg, P < 0.001) due to a decrease in SVR. Injections with aged LOM emulsions (>48 h since manufacture) resulted in a higher incidence of hemodynamic collapse during the observation period (P = 0.02).LOMs may be injected in quantities sufficient to deliver clinically meaningful volumes of oxygen but cause significant decrements in blood pressure and elevations in PVR.
Keywords: hemodynamics; hypoxia; microbubble; oxygen; phospholipid
A Dose Ranging Pharmacokinetic Evaluation of IQP-0528 Released from Intravaginal Rings in Non-Human Primates by Jonathan T. Su; Ryan S. Teller; Priya Srinivasan; Jining Zhang; Amy Martin; Samuel Sung; James M. Smith; Patrick F. Kiser (2163-2171).
Design of intravaginal rings (IVRs) for delivery of antiretrovirals is often guided by in vitro release under sink conditions, based on the assumption that in vivo release will follow a similar release profile.We conducted a dose-ranging study in the female reproductive tract of pigtail macaques using matrix IVRs containing IQP-0528, a poorly soluble but highly potent antiretroviral drug with an IC90 of 146 ng/mL. These IVRs consisted of drug-loaded segments, 15.6% IQP-0528 in Tecoflex 85A, comprising either all, half, or a quarter of the entire ring. In vitro release under sink conditions demonstrates loading-proportional release, with a cumulative 30-day release of 48.5 ± 2.2 mg for our 100% loaded ring, 24.8 ± .36 mg from our 50% loaded ring, and 13.99 ± 1.58 mg from our 25% loaded ring. In vivo, while drug concentration in vaginal fluid is well in excess of IQP-0528’s EC90, we find no statistical difference between the different ring loadings in either swab drug levels or drug released from our rings.We show that in vitro release may not accurately reflect in vivo release, particularly for poorly soluble drugs. All tested loadings of our IVRs are capable of delivering IQP-0528 well in excess of the IC90.
Keywords: intravaginal rings; IQP-0528; macaque; pharmacokinetics
Chitooligosaccharides Modified Reduction-Sensitive Liposomes: Enhanced Cytoplasmic Drug Delivery and Osteosarcomas-Tumor Inhibition in Animal Models by Xuelei Yin; Yingying Chi; Chuanyou Guo; Shuaishuai Feng; Jinhu Liu; Kaoxiang Sun; Zimei Wu (2172-2184).
To investigate the potential of a reduction-sensitive and fusogenic liposomes, enabled by surface-coating with chotooligosaccharides (COS) via a disulfide linker, for tumor-targeted cytoplasmic drug delivery.COS (MW2000-5000) were chemically tethered onto the liposomes through a disulfide linker (-SS-) to cholesterol (Chol). Doxorubicin (DOX) was actively loaded in the liposomes. Their reduction-sensitivities, cellular uptake, cytotoxicity, pharmacokinetics and antitumor efficacy were investigated.The Chol-SS-COS/DOX liposomes (100 nm) had zeta potential of 33.9 mV and high drug loading (13% w/w). The liposomes were stable with minimal drug leakage under physiological conditions but destabilized in the presence of reducing agents, dithiothreitol (DTT) or glutathione (GSH) at 10 mM, the cytosolic level. MTT assay revealed that the cationic Chol-SS-COS/DOX liposomes had higher cytotoxicity to MG63-osteosarcoma cells than non-reduction sensitive liposome (Chol-COS/DOX). Flow cytometry and confocal microscopy revealed that Chol-SS-COS/DOX internalized more efficiently than Chol-COS/DOX with more content to cytoplasm whereas Chol-COS/DOX located around the cell membrane. Chol-SS-COS/DOX preferentially internalized into MG63 cancer cell over LO2 normal liver cells. In rats both liposomes produced a prolonged half-life of DOX by 4 - 5.5 fold (p < 0.001) compared with the DOX solution. Chol-SS-COS/DOX exhibited strong inhibitory effect on tumor growth in MG63 cell-bearing nude mice (n = 6), and extended animal survival rate.Reduction-responsive Chol-SS-COS liposomes may be an excellent platform for cytoplasmic delivery of anticancer drugs. Conjugation of liposomes with COS enhanced tumor cell uptake, antitumor effect and survival rate in animal models.
Keywords: Chotooligosaccharides (COS); Cationic liposomes; Reduction-sensitivity; Cytoplasmic delivery; Tumor-suppression; Survival rate
Design, Preparation and Evaluation of HPMC-Based PAA or SA Freeze-Dried Scaffolds for Vaginal Delivery of Fluconazole by Carmen Anatolia Gafitanu; Daniela Filip; Corina Cernatescu; Daniela Rusu; Cristina Gabriela Tuchilus; Doina Macocinschi; Mirela-Fernanda Zaltariov (2185-2196).
Aim of this work was preparation of bioadhesive gel formulations based on Hydroxypropyl methylcellulose (HPMC), Poly(acrylic acid) (PAA) or Sodium alginate (SA) loaded with anise/fluconazole β-cyclodextrin inclusion complexes in 1:2 and 1:3 ratios intended for vaginal applications.Freeze-drying method was effectively utilized and superporous morphology was obtained. The superporous morphology of the lyophilized gels, dynamic water vapor sorption measurements, drug release kinetics studies and their antimicrobial activities are presented.HPMC content influences especially the sorption/desorption behaviour of HPMC-based PAA gels and the morphology of the gel formulations with fluconazole/β-cyclodextrin inclusion complexes, due to the interactions among the gel networks absorbing water molecules. It was found that fluconazole release kinetics correspond to quasi-Fickian, Fickian diffusion and non-Fickian mechanisms for the studied hydrogels. The tested vaginal formulations with β-cyclodextrin inclusion complexes exhibited selectivity toward S. aureus ATCC 25923 and all tested Candida strains in comparison with the gel formulation without β-cyclodextrin.The fluconazole/β cyclodextrin inclusion complexes ensure a controlled release of fluconazole over a few days, the highest amount of drug release (92%) being observed after 43 h. These bioadhesive gel formulations could be very promising topical alternative for treatment of vaginal fungal infections.
Keywords: antimicrobial activity; bioadhesive formulations; fluconazole release; vaginal gel
Rhamnolipids Enhance in Vivo Oral Bioavailability of Poorly Absorbed Molecules by El-Sayed Khafagy; Mona F. El-Azab; Mohamed E. H. ElSayed (2197-2210).
This report describes the effect of rhamnolipids (RLs) on the tight junctions (TJ) of the intestinal epithelium using the rat in-situ closed loop model.We investigated the transport of 5 (6)-carboxyfluorescein (CF) and fluorescein isothiocyanate-labeled dextrans with average molecular weights of 4.4 and 10 kDa (FD-4 and FD-10) when co-administered with different concentrations of RLs. Lactate dehydrogenase (LDH) leakage assay and histopathological examination of treated intestinal loops were used to assess potential toxicity of RLs. Further, the effect of kaempferol on accelerating the resealing of the tight junctions in vivo was also investigatedData shows that administration of different RLs concentrations (1.0–5.0% v/v) increased CF absorption through rat intestine by 2.84- and 15.82-folds with RLs concentrations of 1.0% and 5.0% v/v, respectively. RLs exhibited size-dependent increase on FD-4 and FD-10 absorption. Dosing RLs at 1.0% v/v didn’t cause a significant LDH leakage or histopathological changes to intestinal mucosa compared to higher concentrations, which showed a progressive damaging effect. Using kaempferol, a natural flavonoid that stimulates the assembly of the TJs, proved to enhance the recovery of barrier properties of the intestinal mucosa treated with high concentrations of RLs (2.5% and 5% v/v).These results collectively illustrate the ability of RLs to enhance oral bioavailability of different molecules across the intestinal epithelial membrane in a concentration- and time-dependent fashion.
Keywords: Biosurfactant; Intestinal absorption; Kaempferol; Paracellular absorption; Rhamnolipids
Injectable Sustained-Release Depots of PLGA Microspheres for Insoluble Drugs Prepared by hot-Melt Extrusion by Yuting Guo; Yunning Yang; Luying He; Rong Sun; Chenguang Pu; Bin Xie; Haibing He; Yu Zhang; Tian Yin; Yanjiao Wang; Xing Tang (2211-2222).
Progesterone (PRG) was selected as a model drug to develop a long-acting injection system for poorly water-soluble drugs.Microspheres with high density-low porosity were prepared by hot-melt extrusion (HME) combined with wet-milling as the representative formulation, and a microcrystal suspension was also studied as a comparison. The morphology, particle size and distribution, polymorphism, drug distribution, density and porosity were characterized by scanning electron microscopy, laser diffraction particle size analyzer, power X-ray diffraction and DSC respectively. The in vivo performance of the different formulations within 7 days after intramuscular injection was evaluated in male SD rats.The drug-loading rate of the microspheres could be as high as 40%. The average initial burst release of the microspheres (PLGA lactide:glycolide = 75:25) was only 6.7% much lower than that of the microsuspension (25.7%) and a sustained release was exhibited for at least 7 days. The release mechanism was speculated to be as follows. The microspheres are a drug depot with drug microcrystals in the PLGA matrix which is a layer by layer honeycomb structure.Microspheres prepared by HME combined with wet-milling could achieve a long-term sustained release effect as a novel long-acting formulation strategy.
Keywords: HME; in vivo ; microsphere; PLGA; progesterone