Pharmaceutical Research (v.31, #9)
ABC Transporters in Multi-Drug Resistance and ADME-Tox of Small Molecule Tyrosine Kinase Inhibitors by Jiexin Deng; Jie Shao; John S. Markowitz; Guohua An (2237-2255).
The past decade has seen tremendous efforts in the research and development of new chemotherapeutic drugs using target-based approaches. These efforts have led to the discovery of small molecule tyrosine kinase inhibitors (TKIs). Following the initial approval of imatinib by the US FDA in 2001, more than 15 TKIs targeting different tyrosine kinases have been approved, and numerous others are in various phases of clinical evaluation. Unlike conventional chemotherapy that can cause non-discriminating damage to both normal and cancerous cells, TKIs attack cancer-specific targets and therefore have a more favorable safety profile. However, although TKIs have had outstanding success in cancer therapy, there has been increasing evidence of resistance to TKIs. The enhanced efflux of TKIs by ATP-binding cassette (ABC) transporters over-expressed in cancer cells has been found to be one such important resistance mechanism. Another major drawback of TKI therapies that has been increasingly recognized is the extensive inter-individual pharmacokinetic variability, in which ABC transporters seem to play a major role as well. This review covers recent findings on the interactions of small molecule TKIs with ABC transporters. The effects of ABC transporters on anticancer efficacy and the absorption, distribution, metabolism, excretion, and toxicity (ADME-Tox) of the small molecule TKIs are summarized in detail. Since TKIs have been found to not only serve as substrates of ABC transporters, but also as modulators of these proteins via inhibition or induction, their influence upon ABC transporters and potential role on TKI-drug interactions are discussed as well.
Keywords: ABC transporters; multi-drug resistance ; ADME-Tox; tyrosine kinase inhibitors; molecular targeted anticancer therapy
Scale of Health: Indices of Safety and Efficacy in the Evolving Environment of Large Biological Datasets by Christie M. Sayes; Herman Staats; Anthony J. Hickey (2256-2265).
The interdependent relationship between pharmacology and toxicology is fundamental to the concepts of efficacy and safety of both drugs and xenobiotics. The traditional concept of establishing efficacious and tolerated doses to define a ‘therapeutic window’ appears simplistic in the context of an exponentially increasing database on molecular mechanisms and cell biology that inform our understanding of homeostasis. Recent advances in nano medicine illustrate the convergence of efficacy and safety considerations that are central to establishing a clear pathway for regulatory review. The following overview considers biological responses to the administration of nanoparticles and the scale of balanced, within a range that might be considered ‘normal’, to unbalanced, abnormal responses associated with health and disease.
Keywords: drugs; immunity; inflammation; nanoparticles; vaccines
Directed Self-assembled Nanoparticles of Probucol Improve Oral Delivery: Fabrication, Performance and Correlation by Zhiwen Zhang; Shijun Jiang; Zeying Liu; Baohua Niu; Wangwen Gu; Yaping Li; Jingbin Cui (2266-2275).
We are reporting on the development of a unique drug delivery platform by directed self-assembly technique to improve the oral delivery of hydrophobic drugs.Herein, a series of probucol directed self-assembled nanoparticles (PDN) were developed with two components of probucol and surfactant such as Tween 20, Tween 80, D-alpha-tocopheryl polyethylene glycol 1,000 succinate (TPGS) and HS-15, which was respectively named as T20-PDN, T80-PDN, TP-PDN and HS-PDN. The formation of various PDNs was determined by in vitro characterization and the physicochemical properties of these PDNs were determined. Moreover, the performance of PDN in enhancing the oral delivery and possible correlation between the in vitro properties and in vivo performances were investigated.PDN was homogenous nanometer-sized particles with negative surface charge. The cellular uptake of probucol in Caco-2 cell monolayer was respectively increased 1.15, 1.82, 1.59 and 5.31-fold by these PDN. In particular, the oral bioavailability of these PDN was significantly improved 3.0, 4.1, 5.4 and 10.4 folds compared with the free drug suspension. The enhanced cellular uptake and oral bioavailability were correlated with the characters of involved surfactants and the particle size of PDN.Thereby, the directed self-assembled nanoparticles could provide a new strategy for enhancing the oral delivery of hydrophobic drugs.
Keywords: correlation; directed self-assembly; nanoparticles; oral delivery; probucol
Gemcitabine Treatment of Rat Soft Tissue Sarcoma with Phosphatidyldiglycerol-Based Thermosensitive Liposomes by Simone Limmer; Jasmin Hahn; Rebecca Schmidt; Kirsten Wachholz; Anja Zengerle; Katharina Lechner; Hansjörg Eibl; Rolf D. Issels; Martin Hossann; Lars H. Lindner (2276-2286).
The pyrimidine analogue gemcitabine (dFdC) is frequently used in the treatment of patients with solid tumors. However, after i.v. application dFdC is rapidly inactivated by metabolization. Here, the potential of thermosensitive liposomes based on 1,2-dipalmitoyl-sn-glycero-3-phosphodiglycerol (DPPG2-TSL) were investigated as carrier and targeting system for delivery of dFdC in combination with local hyperthermia (HT).DPPG2-TSL were prepared by the lipid film hydration and extrusion method and characterized by dynamic light scattering, thin layer chromatography, phosphate assay and HPLC. In vivo experiments were performed in Brown Norway rats with a syngeneic soft tissue sarcoma. Local HT treatment was performed by light exposure.DPPG2-TSL were stable at 37°C in serum and showed a temperature dependent dFdC release >40°C. Plasma half-life of dFdC was strongly increased from 0.07 h (non-liposomal) to 0.53 h (liposomal, vesicle size 105 nm) or 2.59 h (liposomal, 129 nm). Therapy of BN175 tumors with dFdC encapsulated in DPPG2-TSL + HT showed significant improvement in tumor growth delay compared to non-liposomal dFdC without HT (p < 0.05), non-liposomal dFdC with HT (p < 0.01), and liposomal dFdC without HT (p < 0.05), respectively.Gemcitabine encapsulated in DPPG2-TSL in combination with local HT is a promising tool for the treatment of solid tumors. Therefore, these encouraging results ask for further investigation and evaluation.
Keywords: drug delivery; gemcitabine; hyperthermia; phosphatidyloligoglycerol; thermosensitive liposomes
A Mechanism Enhancing Macromolecule Transport Through Paracellular Spaces Induced by Poly-L-Arginine: Poly-L-Arginine Induces the Internalization of Tight Junction Proteins via Clathrin-Mediated Endocytosis by Tsutomu Yamaki; Yusuke Kamiya; Kazuo Ohtake; Masaki Uchida; Toshinobu Seki; Hideo Ueda; Jun Kobayashi; Yasunori Morimoto; Hideshi Natsume (2287-2296).
Poly-L-arginine (PLA) enhances the paracellular permeability of the Caco-2 cell monolayer to hydrophilic macromolecules by disappearance of tight junction (TJ) proteins from cell–cell junctions. However, the mechanism of the disappearance of TJ proteins in response to PLA has been unclear. In this study, we investigated the mechanism of disappearance of TJ proteins from cell–cell junctions after the application of PLA to Caco-2 cell monolayers.The membrane conductance (Gt), FITC-dextran (FD-4) permeability, and localization of TJ proteins were examined after the treatment of Caco-2 cell monolayers with PLA in the presence of various endocytosis inhibitors. In addition, the localization of endosome marker proteins was also observed.Clathrin-mediated endocytosis inhibitors suppressed the increase in Gt and Papp of FD-4 induced by PLA, and also significantly suppressed the disappearance of TJ proteins induced by PLA. Furthermore, occludin, one of the TJ proteins, colocalized with early endosome and recycling endosomes after the internalization of occludin induced by PLA, and then was recycled to the cell–cell junctions.PLA induced the transient internalization of TJ proteins in cell–cell junctions via clathrin-mediated endocytosis, subsequently increasing the permeability of the Caco-2 cell monolayer to FD-4 via a paracellular route.
Keywords: absorption enhancer; drug delivery; hydrophilic-macromolecules; poly-L-arginine; tight junction
Prediction of Passive Drug Permeability Across the Blood-Retinal Barrier by Aapo Tervonen; Iina Vainio; Soile Nymark; Jari Hyttinen (2297-2311).
The purpose of this study is to develop a computational model of the physical barrier function of the outer blood-retinal barrier (BRB), which is vital for normal retinal function. To our best knowledge no comprehensive models of BRB has been reported.The model construction is based on the three-layered structure of the BRB: retinal pigment epithelium (RPE), Bruch’s membrane and choriocapillaris endothelium. Their permeabilities were calculated based on the physical theories and experimental material and permeability studies in the literature, which were used to describe diffusional hindrance in specific environments.Our compartmental BRB model predicts permeabilities with magnitudes similar to the experimental values in the literature. However, due to the small number and varying experimental conditions there is a large variability in the available experimental data, rendering validation of the model difficult. The model suggests that the paracellular pathway of the RPE largely defines the total BRB permeability.Our model is the first BRB model of its level and combines the present knowledge of the BRB barrier function. Furthermore, the model forms a platform for the future model development to be used for the design of new drugs and drug administration systems.
Keywords: blood-retinal barrier; permeability; structure-based model; compartmental model; lipophilicity
Investigation of the Effect of Hydroxypropyl Methylcellulose on the Phase Transformation and Release Profiles of Carbamazepine-Nicotinamide Cocrystal by Mingzhong Li; Shi Qiu; Yan Lu; Ke Wang; Xiaojun Lai; Mohammad Rehan (2312-2325).
The aim of this work was to investigate the influence of hydroxypropyl methylcellulose (HPMC) on the phase transformation and release profile of carbamazepine-nicotinamide (CBZ-NIC) cocrystal in solution and in sustained release matrix tablets.The polymorphic transitions of the CBZ-NIC cocrystal and its crystalline properties were examined by differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), Raman spectroscopy, and scanning electron microscopy (SEM).The apparent CBZ solubility and dissolution rate of CBZ-NIC cocrystal were constant in different concentrations of HPMC solutions. In a lower percentage of HPMC in the matrix tablets, the CBZ release profile of the CBZ-NIC cocrystal was nonlinear and declined over time. With an increased HPMC content in the tablets, the CBZ-NIC cocrystal formulation showed a significantly higher CBZ release rate in comparison with the other two formulations of CBZ III and the physical mixture.Because of a significantly improved dissolution rate of the CBZ-NIC cocrystal, the rate of CBZ entering into solution is significantly faster than the rate of formation of the CBZ-HPMC soluble complex in solution, leading to a higher supersaturation level of CBZ and subsequently precipitation of CBZ dihydrate.
Keywords: carbamazepine-nicotinamide (CBZ-NIC) cocrystal; hydroxypropyl methylcellulose (HPMC); inhibition; phase transformation; UV imaging
In Vitro Efficacy of Polysaccharide-Based Nanoparticles Containing Disease-Modifying Antirheumatic Drugs by Nan Zhang; Patricia R. Wardwell; Rebecca A. Bader (2326-2334).
To evaluate the therapeutic efficacy of dexamethasone (DM) and methotrexate (MTX) entrapped within polysialic acid (PSA)-trimethyl chitosan (TMC) nanoparticles using an in vitro model of rheumatoid arthritis (RA).The loading capacity of the PSA-TMC nanoparticles was determined. An RA in vitro model was developed by stimulating a synovial cell line with a proinflammatory mediator. Multiplex immunoassay was used to determine changes in the secretion of interleukin-6 (IL-6), interleukin-8 (IL-8), and granulocyte-macrophage colony-stimulating factor (GM-CSF) by the in vitro model following administration of the DM- and MTX-loaded nanoparticles.The loading capacity of the PSA-TMC nanoparticles was approximately 0.1 mg of drug/mg of nanoparticle. When applied to our in vitro model of RA, there were no significant differences in the concentrations of IL-6 and IL-8 when comparing the free drugs and drug-loaded nanoparticles, administered at concentration of 0.1 mg/ml and 1.0 mg/ml, respectively.The present study verified that MTX and DM are able to retain bioactivity when loaded into PSA-TMC nanoparticles. Although in vitro efficacy was not increased, the in vivo efficacy will likely be enhanced by the site-specific targeting conferred by nanoparticle entrapment.
Keywords: chitosan; drug delivery; nanoparticles; polysialic acid; rheumatoid arthritis
Impact of Airborne Particle Size, Acoustic Airflow and Breathing Pattern on Delivery of Nebulized Antibiotic into the Maxillary Sinuses Using a Realistic Human Nasal Replica by Lara Leclerc; Jérémie Pourchez; Gérald Aubert; Sandrine Leguellec; Laurent Vecellio; Michèle Cottier; Marc Durand (2335-2343).
Improvement of clinical outcome in patients with sinuses disorders involves targeting delivery of nebulized drug into the maxillary sinuses. We investigated the impact of nebulization conditions (with and without 100 Hz acoustic airflow), particle size (9.9 μm, 2.8 μm, 550 nm and 230 nm) and breathing pattern (nasal vs. no nasal breathing) on enhancement of aerosol delivery into the sinuses using a realistic nasal replica developed by our team.After segmentation of the airways by means of high-resolution computed tomography scans, a well-characterized nasal replica was created using a rapid prototyping technology. A total of 168 intrasinus aerosol depositions were performed with changes of aerosol particle size and breathing patterns under different nebulization conditions using gentamicin as a marker.The results demonstrate that the fraction of aerosol deposited in the maxillary sinuses is enhanced by use of submicrometric aerosols, e.g. 8.155 ± 1.476 mg/L of gentamicin in the left maxillary sinus for the 2.8 μm particles vs. 2.056 ± 0.0474 for the 550 nm particles. Utilization of 100-Hz acoustic airflow nebulization also produced a 2- to 3-fold increase in drug deposition in the maxillary sinuses (e.g. 8.155 ± 1.476 vs. 3.990 ± 1.690 for the 2.8 μm particles).Our study clearly shows that optimum deposition was achieved using submicrometric particles and 100-Hz acoustic airflow nebulization with no nasal breathing. It is hoped that our new respiratory nasal replica will greatly facilitate the development of more effective delivery systems in the future.
Keywords: aerosol therapy; drug deposition; maxillary sinuses; nasal replica
Intravaginal Flux Controlled Pump for Sustained Release of Macromolecules by Ryan S. Teller; Rachna Rastogi; Todd J. Johnson; Michael J. Blair; Robert W. Hitchcock; Patrick F. Kiser (2344-2353).
To design a flux controlled pump (FCP) capable of 30-day, controlled release of macromolecules to the vaginal mucosa.The FCP is composed of a single chamber fabricated from a rigid thermoplastic with orifices and encloses a pellet of water-swellable polymer containing the drug substance. We performed testing both in vitro and in rabbits. To ensure vaginal retention in the rabbit, we designed and attached an oval shape-memory polyether urethane retainer to the FCP allowing for long-term intravaginal evaluation of a solid dosage form without invasive surgical implantation.The orifices and swelling properties of the polymer pellet control water entry for polymer hydration and expansion, and subsequent extrusion of the drug-containing gel from the orifice. A FCP device containing a pellet composed of hydroxypropyl cellulose compounded with a model macromolecule, achieved controlled in vitro release for 30 days with an average release rate of 24 ± 2 μg/day (mean ± SD) and range of 16 to 42 μg/day. We observed a slightly lower average release rate in vivo of 20 ± 0.6 μg/day (mean ± SD).The size of the orifice and nature of the swelling polymer controls the hydration rate and thereby macromolecule release rate and duration from this FCP.
Keywords: in vivo evaluation; macromolecules; non-surgical implantation; vaginal delivery
Ultrasound Enhanced PEI-Mediated Gene Delivery Through Increasing the Intracellular Calcium Level and PKC-δ Protein Expression by Jyun-Lin Lee; Chia-Wen Lo; Claude Inserra; Jean-Christophe Béra; Wen-Shiang Chen (2354-2366).
Polyethylenimine (PEI), a cationic polymer, has been shown to aggregate plasmid DNA and facilitate its internalization. It has also been shown that combining ultrasound (US) with PEI could enhance and prolong in vitro and in vivo transgene expression. However, the role US in the enhancement of PEI uptake is poorly understood. This study investigates the impact of US on PEI-mediated gene transfection.Specific endocytosis pathway siRNA, including clathrin HC siRNA, caveolin-1 siRNA and protein kinase C-delta (PKC-δ) siRNA, are used to block the corresponding endocytosis pathways prior to the transfection of luciferase DNA/PEI polyplexes to cultured cells by 1-MHz pulsed US with ultrasound contrast agent SonoVue®.Transgene expression was found not to be enhanced by US treatment in the presence of the PKC-δ siRNA. We further demonstrated that PKC-δ protein could be enhanced at 6 h after US exposure. Moreover, intracellular calcium levels were found to be significantly increased at 3 h after US exposure, while transgene expressions were significantly reduced in the presence of calcium channel blockers both in vitro and in vivo.Our results suggest that US enhanced PEI-mediated gene transfection specifically by increasing PKC-δ related fluid phase endocytosis, which was induced by increasing the intracellular calcium levels.
Keywords: calcium; fluid phase endocytosis; PKC-δ; polyethylenimine; ultrasound
Reduced Physiologically-Based Pharmacokinetic Model of Repaglinide: Impact of OATP1B1 and CYP2C8 Genotype and Source of In Vitro Data on the Prediction of Drug-Drug Interaction Risk by Michael Gertz; Nikolaos Tsamandouras; Carolina Säll; J. Brian Houston; Aleksandra Galetin (2367-2382).
To investigate the effect of OATP1B1 genotype as a covariate on repaglinide pharmacokinetics and drug-drug interaction (DDIs) risk using a reduced physiologically-based pharmacokinetic (PBPK) model.Twenty nine mean plasma concentration-time profiles for SLCO1B1 c.521T>C were used to estimate hepatic uptake clearance (CLuptake) in different genotype groups applying a population approach in NONMEM v.7.2.Estimated repaglinide CLuptake corresponded to 217 and 113 μL/min/106 cells for SLCO1B1 c.521TT/TC and CC, respectively. A significant effect of OATP1B1 genotype was seen on CLuptake (48% reduction for CC relative to wild type). Sensitivity analysis highlighted the impact of CLmet and CLdiff uncertainty on the CLuptake optimization using plasma data. Propagation of this uncertainty had a marginal effect on the prediction of repaglinide OATP1B1-mediated DDI with cyclosporine; however, sensitivity of the predicted magnitude of repaglinide metabolic DDI was high. In addition, the reduced PBPK model was used to assess the effect of both CYP2C8*3 and SLCO1B1 c.521T>C on repaglinide exposure by simulations; power calculations were performed to guide prospective DDI and pharmacogenetic studies.The application of reduced PBPK model for parameter optimization and limitations of this process associated with the use of plasma rather than tissue profiles are illustrated.
Keywords: drug-drug interactions; OATP1B1; physiologically-based pharmacokinetic models; repaglinide
Magnetic Resonance Microscopy for Assessment of Morphological Changes in Hydrating Hydroxypropylmethylcellulose Matrix Tablets In Situ–Is it Possible to Detect Phenomena Related to Drug Dissolution Within the Hydrated Matrices? by Piotr Kulinowski; Anna Młynarczyk; Krzysztof Jasiński; Przemysław Talik; Marco L. H. Gruwel; Bogusław Tomanek; Władysław P. Węglarz; Przemysław Dorożyński (2383-2392).
So far, the hydrated part of the HPMC matrix has commonly been denoted as a “gel” or “pseudogel” layer. No MRI-based results have been published regarding observation of internal phenomena related to drug dissolution inside swelling polymeric matrices during hydration. The purpose of the study was to detect such phenomena.Multiparametric, spatially and temporally resolved T2 MR relaxometry, in situ, was applied to study formation of the hydration progress in HPMC matrix tablets loaded with L-dopa and ketoprofen using a 11.7 T MRI system. Two spin-echo based pulse sequences were used, one of them specifically designed to study short T2 signals.Two components in the T2 decay envelope were estimated and spatial distributions of their parameters, i.e. amplitudes and T2 values, were obtained. Based on the data, different region formation patterns (i.e. multilayer structure) were registered depending on drug presence and solubility. Inside the matrix with incorporated sparingly soluble drug a specific layer formation due to drug dissolution was detected, whereas a matrix with very slightly soluble drug does not form distinct external “gel-like” layer.We have introduced a new paradigm in the characterization of hydrating matrices using 1H MRI methods. It reflects molecular mobility and concentration of water inside the hydrated matrix. For the first time, drug dissolution related phenomena, i.e. particular front and region formation, were observed by MRI methods.
Keywords: controlled release (CR); HPMC; hydrophilic matrices; magnetic resonance imaging (MRI); MR T2 relaxometry
Vaccine Delivery to the Oral Cavity Using Coated Microneedles Induces Systemic and Mucosal Immunity by Yunzhe Ma; Wenqian Tao; Shelly J. Krebs; William F. Sutton; Nancy L. Haigwood; Harvinder S. Gill (2393-2403).
The objective of this study is to evaluate the feasibility of using coated microneedles to deliver vaccines into the oral cavity to induce systemic and mucosal immune responses.Microneedles were coated with sulforhodamine, ovalbumin and two HIV antigens. Coated microneedles were inserted into the inner lower lip and dorsal surface of the tongue of rabbits. Histology was used to confirm microneedle insertion, and systemic and mucosal immune responses were characterized by measuring antigen-specific immunoglobulin G (IgG) in serum and immunoglobulin A (IgA) in saliva, respectively.Histological evaluation of tissues shows that coated microneedles can penetrate the lip and tongue to deliver coatings. Using ovalbumin as a model antigen it was found that the lip and the tongue are equally immunogenic sites for vaccination. Importantly, both sites also induced a significant (p < 0.05) secretory IgA in saliva compared to pre-immune saliva. Microneedle-based oral cavity vaccination was also compared to the intramuscular route using two HIV antigens, a virus-like particle and a DNA vaccine. Microneedle-based delivery to the oral cavity and the intramuscular route exhibited similar (p > 0.05) yet significant (p < 0.05) levels of antigen-specific IgG in serum. However, only the microneedle-based oral cavity vaccination group stimulated a significantly higher (p < 0.05) antigen-specific IgA response in saliva, but not intramuscular injection.In conclusion, this study provides a novel method using microneedles to induce systemic IgG and secretory IgA in saliva, and could offer a versatile technique for oral mucosal vaccination. Figure ᅟ
Keywords: lip vaccination; mucosal vaccination; oral cavity vaccination; oral HIV; tongue vaccination
In Vitro and In Situ Evaluation of pH-Dependence of Atazanavir Intestinal Permeability and Interactions with Acid-Reducing Agents by Olena Kis; Sharon L. Walmsley; Reina Bendayan (2404-2419).
The objectives of this study were to evaluate the effects of intestinal lumen pH, food intake, and acid-reducing agents on the intestinal permeability of atazanavir, an HIV-1 protease inhibitor.Atazanavir permeability across Caco-2 cell monolayers (P app) and in situ steady-state permeability across rat jejunum and ileum (P eff) were evaluated in buffers of varied pH (4.5–8.5), in fasted- or fed-state simulated intestinal fluid, or in presence of acid-reducing drugs (e.g., omeprazole). In vitro accumulation and apical-to-basolateral P app of atazanavir increased with decreasing pH. This effect appeared to be associated with lower atazanavir efflux by P-glycoprotein at acidic pH (5.5) compared to neutral pH. In situ atazanavir P eff across rat jejunum and ileum also decreased 2.7 and 2.3-fold, respectively, when pH was increased from 4.5 to 8.5. Several acid-reducing agents (e.g., omeprazole) moderately inhibited atazanavir efflux in Caco-2 monolayers; however, this effect was not observed in situ. Fed-state buffer significantly increased atazanavir apical-to-basolateral P app (p < 0.001) and in situ P eff (p < 0.05) compared to fasted-state buffer.Atazanavir permeability is sensitive to changes in intestinal lumen pH. This pH-sensitivity may contribute to atazanavir clinical interactions with acid-reducing agents and variable oral bioavailability.
Keywords: acid-reducing agents; atazanavir; HIV-1 protease inhibitors; intestinal permeability; pH dependence
Solid Lipid Particles for Oral Delivery of Peptide and Protein Drugs II – The Digestion of Trilaurin Protects Desmopressin from Proteolytic Degradation by Philip Carsten Christophersen; Long Zhang; Anette Müllertz; Hanne Mørck Nielsen; Mingshi Yang; Huiling Mu (2420-2428).
To investigate the in vitro release and degradation of desmopressin from saturated triglyceride microparticles under both lipolytic and proteolytic conditions.The release of desmopressin from different solid lipid microparticles in the absence and presence of a microbial lipase and protease was determined. Trilaurin (TG12), trimyristin (TG14), tripalmitin (TG16), and tristearin (TG18) were used as lipid excipients to produce solid lipid microparticles.In the presence of lipase, the rate of drug release from different lipid particles was in the order of TG14 > TG16 > TG18, which is the same rank order as the lipid degradation rate. A reverse rank order was found for the protection of desmopressin from enzymatic degradation due to spatial separation of desmopressin from the protease. TG12 accelerated the release of desmopressin from all lipid particles when added as either drug-free microparticles to the lipolysis medium or incorporated in TG16 particles. Additionally, TG12 particles protected desmopressin from degradation when present in the lipolysis medium with the other lipid microparticles.TG12 is a very interesting lipid for oral lipid formulations containing peptides and proteins as it alters release and degradation of the incorporated desmopressin. The present study demonstrates the possibility of bio-relevant in vitro evaluation of lipid-based solid particles.
Keywords: lipid hydrolysis; peptide and protein drugs; proteolysis; solid lipid particles; triglycerides
Intracellular Ca2+ Release Mediates Cationic but Not Anionic Poly(amidoamine) (PAMAM) Dendrimer-Induced Tight Junction Modulation by Brittany R. Avaritt; Peter W. Swaan (2429-2438).
Poly(amidoamine) (PAMAM) dendrimers show great promise for utilization as oral drug delivery vehicles. These polymers are capable of traversing epithelial barriers, and have been shown to translocate by both transcellular and paracellular routes. While many proof-of-concept studies have shown that PAMAM dendrimers improve intestinal transport, little information exists on the mechanisms of paracellular transport, specifically dendrimer-induced tight junction modulation.Using anionic G3.5 and cationic G4 PAMAM dendrimers with known absorption enhancers, we investigated tight junction modulation in Caco-2 monolayers by visualization and mannitol permeability and compared dendrimer-mediated tight junction modulation to that of established permeation enhancers. [14C]-Mannitol permeability in the presence and absence of phospholipase C-dependent signaling pathway inhibitors was also examined and indicated that this pathway may mediate dendrimer-induced changes in permeability.Differences between G3.5 and G4 in tight junction protein staining and permeability with inhibitors were evident, suggesting divergent mechanisms were responsible for tight junction modulation. These dissimilarities are further intimated by the intracellular calcium release caused by G4 but not G3.5. Based on our results, it is apparent that the underlying mechanisms of dendrimer permeability are complex, and the complexities are likely a result of the density and sign of the surface charges of PAMAM dendrimers.The results of this study will have implications on the future use of PAMAM dendrimers for oral drug delivery.
Keywords: nanomedicine; oral drug delivery; PAMAM dendrimers; paracellular transport; tight junctions
Uptake and Cytotoxicity of Docetaxel-Loaded Hyaluronic Acid-Grafted Oily Core Nanocapsules in MDA-MB 231 Cancer Cells by Ibrahima Youm; Vivek Agrahari; James B. Murowchick; Bi-Botti C. Youan (2439-2452).
It is hypothesized that docetaxel (Doc)-loaded hyaluronic acid (HA)-polyethylene glycol/poly(ε-caprolactone)-grafted oily core nanocapsules (NCs) can enhance the drug cytotoxicity and uptake in CD44 expressing breast cancer (BC) cells (MDA-MB 231).NCs were prepared, optimized and characterized by dynamic light scattering, transmission electron microscopy (TEM), and powder X-ray diffraction (PXRD). In vitro cytotoxicity tests [MTS, level of reactive oxygen species (ROS) and level of reduced glutathione (GSH)] were performed in BC cells. The contribution of CD44 to the NCs cellular uptake was elucidated using an anti CD44 antibody blockage and a CD44 negative NIH3T3 cell line.The optimum formulation of Doc-loaded HA oily core NCs had respective mean diameter, polydispersity, and drug encapsulation efficiency of 224.18 nm, 0.32, and 60.38%. The NCs appeared spherical with low drug crystallinity, while the drug release data fitted to first order equation. Compared to that of ungrafted NCs, the cytotoxicity of Doc-loaded HA-grafted NCs was significantly enhanced (p<0.05). A decrease of the intracellular level of ROS was reversely correlated with that of GSH. Interestingly, the cellular internalization of HA-grafted NCs mediated CD44 was dramatically enhanced (3 to 4-fold) with respect to the absence of specific biomarker or targeting ligand. The use of HA-grafted NCs enhanced the selective drug payload, cytotoxicity and uptake in MDA-MB 231 cells. Therefore, it could be a promising template for safe and effective delivery of Doc and similar chemotherapeutic agents in cancer cells.
Keywords: breast cancer; cancer chemotherapy; CD44 receptor; cytotoxicity; hyaluronic acid; nanocapsules; particle cellular uptake
Local Co-Delivery of Pancreatic Islets and Liposomal Clodronate Using Injectable Hydrogel to Prevent Acute Immune Reactions in a Type 1 Diabetes by Muhammad R. Haque; Dong Yun Lee; Cheol-Hee Ahn; Jee-Heon Jeong; Youngro Byun (2453-2462).
The purpose of this study was to investigate the effect of locally delivered pancreatic islet with liposomal clodronate (Clodrosome®) as an immunoprotection agent for the treatment of type 1 diabetes.The bio-distribution of liposomal clodronate in matrigel was checked by imaging analyzer. To verify the therapeutic efficacy of locally delivered islet with liposomal clodronate using injectable hydrogel, four groups of islet transplanted mice (n = 6 in each group) were prepared: 1) the islet group, 2) the islet-Clodrosome group, 3) the islet-Matrigel group, and 4) the islet-Matrigel-Clodrosome group. Immune cell migration and activation, and pro-inflammatory cytokine secretion was evaluated by immunohistochemistry staining and ELISA assay.Cy5.5 labeled liposomes remained in the matrigel for over 7 days. The median survival time of transplanted islets (Islet-Matrigel-Clodrosome group) was significantly increased (>60 days), compared to other groups. Locally delivered liposomal clodronate in matrigel effectively inhibited the activation of macrophages, immune cell migration and activation, and pro-inflammatory cytokine secretion from macrophages.Locally co-delivered pancreatic islets and liposomal clodronate using injectable hydrogel effectively cured type 1 diabetes. Especially, the inhibition of macrophage attack in the early stage after local delivery of islets was very important for the successful long-term survival of delivered islets.
Keywords: pancreatic islets; liposomal clodronate; injectable hydrogel; local delivery; macrophage depletion
Nanofiber-Coated Drug Eluting Stent for the Stabilization of Mast Cells by Byeongtaek Oh; Chi H. Lee (2463-2478).
The nanofiber-hydrogel blend containing nitric oxide (NO) donors and reactive oxygen species (ROS) scavengers (Edaravone: EDV) was explored as an advanced strategy for stabilization of Mast cells (MCs) to achieve efficient immune-suppressive effects.Three types of nanofiber hydrogel composites (Bare-Nanofibers (BNF), Nanofiber-Hydrogels (NF-Gel) and Cross-linked Nanofiber-Hydrogels (NF-Gel-X)), were evaluated. The degranulation rates of MCs were determined by measurement of the extracellular levels of hydrogen peroxide and the released amounts of β-hexosaminidase from the activated-MCs (a-MCs). In addition, the effects of EDV on the selective scavenging of the oxygen radicals and prevention of peroxynitrite formation were evaluated. The roles of a-MCs in re-endothelialization and viability of coronary artery endothelial cells (hPCAECs) were defined using alamar blue and LDH assay, respectively.Each polymer matrix has unique morphological characteristics. The effects of EDV (~1.0 mM) on the production of NO were greatly influenced by the presence of superoxide or hydroxyl radicals. NF-G-X containing a mixture of EDV and S-Nitroglutathione (GSNO) produced the highest level of NO under the oxidative stress conditions. GSNO alone or a mixture of GSNO and EDV significantly lowered the degranulation rate of a-MCs (GSNO only: 55.8 ± 5.4%; GSNO with EDV: 50.6 ± 0.6%), indicating that NO plays an integral role in degranulation of a-MCs. There were no significant biochemical evidences of cytotoxic effects of GSNO and EDV on the hPCAECs.Nanofibers containing a mixture of nitric oxide donors and ROS scavengers could be used as a promising strategy to stabilize MCs from the ROS-mediated immune responses.
Keywords: Edaravone (EDV); mast cells; nanofiber; nitric oxide (NO); reactive oxygen species (ROS)
Characterization and Evaluation of Multi-Component Crystals of Hydrochlorothiazide by Renu Chadha; Swati Bhandari; Sadhika Khullar; Sanjay K. Mandal; D. V. S. Jain (2479-2489).
The present work aims at improving the physicochemical properties of hydrochlorothiazide, a poorly water soluble antihypertensive drug by preparing its multi-component crystals with nicotinic acid (HCT-NA) and 2-picolinic acid (HCT-PIC).The crystals prepared by solution crystallization were investigated by thermoanalytical techniques. The crystal structures of HCT-NA (1) and HCT-PIC (2) were determined by the single crystal X-ray diffraction and were assessed for their aqueous solubility, antihypertensive activity and acute toxicity in rats.Both 1 and 2 crystallized in the orthorhombic space group P212121 and formation of salts were confirmed. The solubility profiles of 1 and 2 in basic media showed a maximum release of 2.5 mg/ml and 1.9 mg/ml, respectively, in comparison to the drug (0.82 mg/ml). The in-vivo antihypertensive activity of 1 in deoxycorticosterone acetate salt induced hypertensive rats showed 1.5 fold improvement. No increase in the signs of toxicity were revealed in rats during the acute toxicity studies even at doses of 2,000 mg/kg by body weight in comparison to the free drug. Histopathological findings supported the safety of these multi-component crystals.The new solid phases exhibit potential to be explored for the oral drug delivery of HCT with improved solubility and therapeutic outcome.
Keywords: acute toxicity; antihypertensive activity; multi-component crystals; poorly water soluble drugs; solubility
Development of EGFR-Targeted Nanoemulsion for Imaging and Novel Platinum Therapy of Ovarian Cancer by Srinivas Ganta; Amit Singh; Niravkumar R. Patel; Joseph Cacaccio; Yashesh H. Rawal; Barbara J. Davis; Mansoor M. Amiji; Timothy P. Coleman (2490-2502).
Platinum-based chemotherapy is the treatment of choice for malignant epithelial ovarian cancers, but generalized toxicity and platinum resistance limits its use. Theranostic nanoemulsion with a novel platinum prodrug, myrisplatin, and the pro-apoptotic agent, C6-ceramide, were designed to overcome these limitations.The nanoemulsions, including ones with an EGFR binding peptide and gadolinium, were made using generally regarded as safe grade excipients and a high shear microfluidization process. Efficacy was evaluated in ovarian cancer cells, SKOV3, A2780 and A2780CP.The nanoemulsion with particle size <150 nm were stable in plasma and parenteral fluids for 24 h. Ovarian cancer cells in vitro efficiently took up the non-targeted and EGFR-targeted nanoemulsions; improved cytotoxicity was observed for the these nanoemulsions with the latter showing a 50-fold drop in the IC50 in SKOV3 cells as compared to cisplatin alone. The addition of gadolinium did not affect cell viability in vitro, but showed relaxation times comparable to Magnevist®.The myrisplatin/C6-ceramide nanoemulsion synergistically enhanced in vitro cytotoxicity. An EGFR binding peptide addition further increased in vitro cytotoxicity in EGFR positive cancer cells. The diagnostic version showed MR imaging similar to the clinically relevant Magnevist® and may be suitable as a theranostic for ovarian cancer.
Keywords: C6-ceramide; EGFR; gadolinium; MRI; nanoemulsion; ovarian cancer; platinum
Delivery of a Monomeric p53 Subdomain with Mitochondrial Targeting Signals from Pro-Apoptotic Bak or Bax by Karina J. Matissek; Abood Okal; Mohanad Mossalam; Carol S. Lim (2503-2515).
p53 targeted to the mitochondria is the fastest and most direct pathway for executing p53 death signaling. The purpose of this work was to determine if mitochondrial targeting signals (MTSs) from pro-apoptotic Bak and Bax are capable of targeting p53 to the mitochondria and inducing rapid apoptosis.p53 and its DNA-binding domain (DBD) were fused to MTSs from Bak (p53-BakMTS, DBD-BakMTS) or Bax (p53-BaxMTS, DBD-BaxMTS). Mitochondrial localization was tested via fluorescence microscopy in 1471.1 cells, and apoptosis was detected via 7-AAD in breast (T47D), non-small cell lung (H1373), ovarian (SKOV-3) and cervical (HeLa) cancer cells. To determine that apoptosis is via the intrinsic apoptotic pathway, TMRE and caspase-9 assays were conducted. Finally, the involvement of p53/Bak specific pathway was tested.MTSs from Bak and Bax are capable of targeting p53 to the mitochondria, and p53-BakMTS and p53-BaxMTS cause apoptosis through the intrinsic apoptotic pathway. Additionally, p53-BakMTS, DBD-BakMTS, p53-BaxMTS and DBD-BaxMTS caused apoptosis in T47D, H1373, SKOV-3 and HeLa cells. The apoptotic mechanism of p53-BakMTS and DBD-BakMTS was Bak dependent.Our data demonstrates that p53-BakMTS (or BaxMTS) and DBD-BakMTS (or BaxMTS) cause apoptosis at the mitochondria and can be used as a potential gene therapeutic in cancer.
Keywords: apoptosis; Bak; Bax; mitochondria; p53
Co-delivery of Sildenafil (Viagra®) and Crizotinib for Synergistic and Improved Anti-tumoral Therapy by João G. Marques; Vítor M. Gaspar; David Markl; Elisabete C. Costa; Eugénia Gallardo; Ilídio J. Correia (2516-2528).
Cancer multi-drug resistance is a major issue associated with current anti-tumoral therapeutics. In this work, Crizotinib an anti-tumoral drug approved for the treatment of non-small lung cancer in humans, and Sildenafil (Viagra®), were loaded into micellar carriers to evaluate the establishment of a possible synergistic anti-tumoral effect in breast cancer cells.Micellar carriers comprised by PEG-PLA block co-polymers were formulated by the solvent displacement method in which the simultaneous encapsulation of Crizotinib and Sildenafil was promoted. Encapsulation efficiency was analyzed by a new UPLC method validated for this combination of compounds. Micelle physicochemical characterization and cellular uptake were characterized by light scattering and confocal microscopy. The bio- and hemocompatibility of the carriers was also evaluated. MCF-7 breast cancer cells were used to investigate the synergistic anti-tumoral effect.Our results demonstrate that this particular combination induces massive apoptosis of breast cancer cells. The co-delivery of Crizotinib and Sildenafil was only possible due to the high encapsulation efficiency of the micellar systems (>70%). The micelles with size ranging between 93 and 127 nm were internalized by breast cancer cells and subsequently released their payload in the intracellular compartment. The results obtained demonstrated that the delivery of both drugs by micellar carriers led to a 2.7 fold increase in the anti-tumoral effect, when using only half of the concentration that is required when free drugs are administered.Altogether, co-delivery promoted a synergistic effect and demonstrated for the first time the potential of PEG-PLA-Crizotinib-Sildenafil combination for application in cancer therapy.
Keywords: anti-tumoral effect; block co-polymers; breast cancer; co-delivery; synergistic effect
In Vitro- In Vivo Correlation’s Dissolution Limits Setting by B. Roudier; B. M. Davit; E. Beyssac; J-M. Cardot (2529-2538).
In vitro in vivo correlation (IVIVC) is a biopharmaceutical tool recommended for use in formulation development. When validated, IVIVC can be used to set dissolution limits and, based on the dissolution limits, as a surrogate for an in vivo study. The purpose of this paper is to study the various methods used to fix dissolution limits.Fixing dissolution limits is not a straightforward process; various approaches exist. The classical ±10% of dissolution limits was compared to the recommended ±10% of Cmax and AUC and to an innovative back calculation of the 90% CI. Based on simulated values the influence of the calculation method as well as of the variability of the results and pharmacokinetic processes was investigated.Depending upon the method, the results are different and their comparison leads to possible rules. It appears that the usage of a back calculation of a 90% CI is an accurate and advantageous method when intra-individual variability associated with the drug is low. Those findings are in accordance with the current practice of IVIVC, which is not recommended for highly variable drugs.The approach of using a 90% CI allows the intra-subject variability to be taken into account and fixes limits that ensure a greater chance to show acceptable BE, in case of reasonable intra-subject variability, leading to setting broader in vitro dissolution limits compared to classical solutions.
Keywords: in vitro in vivo correlation (IVIVC); dissolution limits; biowaiver; prediction; predictability
Laurate Permeates the Paracellular Pathway for Small Molecules in the Intestinal Epithelial Cell Model HT-29/B6 via Opening the Tight Junctions by Reversible Relocation of Claudin-5 by Isabel Dittmann; Maren Amasheh; Susanne M. Krug; Alexander G. Markov; Michael Fromm; Salah Amasheh (2539-2548).
To mechanistically analyze effects of the medium-chain fatty acid laurate on transepithelial permeability in confluent monolayers of the intestinal epithelial cell line HT-29/B6, in context with an application as an absorption enhancer improving transepithelial drug permeation.Transepithelial resistance and apparent permeability for paracellular flux markers was measured using Ussing-type chambers. Two-path impedance spectroscopy was employed to differentiate between transcellular and paracellular resistance, and confocal imaging and Western blotting was performed.Laurate resulted in a substantial and reversible decrease in transepithelial resistance by 50% which was attributed to a decrease in paracellular resistance. Simultaneously, an increase in permeability for fluorescein (330 Da) was detected, while permeabilities for 4 kDa FITC-dextran and sulpho-NHS-SS-biotin (607 Da) remained unaltered. Confocal laser-scanning microscopy revealed a marked reduction of claudin-5, while other tight junction proteins including tricellulin, a protein preventing the paracellular passage of macromolecules, were not affected.Laurate induces an increase in paracellular permeability for molecules up to a molecular mass of 330 Da by retrieval of claudin-5 from tight junctions without affecting tricellular contacts and the paracellular passage of macromolecules. We hereby provide, for the first time, a mechanistical explanation of laurate-induced permeability enhancement on molecular level.
Keywords: absorption enhancer; drug uptake; epithelial cell; tight junctions
Dipole-Dipole Interaction in Antibody Solutions: Correlation with Viscosity Behavior at High Concentration by Shubhadra N. Singh; Sandeep Yadav; Steven J. Shire; Devendra S. Kalonia (2549-2558).
The purpose of this study was to investigate the contribution of the dipole moment to overall protein-protein interactions and viscosity of a monoclonal antibody MAb1.The dipole moment of MAb1 was measured at various solution pH conditions using dielectric relaxation spectroscopy.The dipole moment for MAb1 was highest at pH 6.5, and the pH dependent change in molecular dipole correlated fairly well with previously observed trends of viscosity and storage modulus versus pH. Moreover, the magnitude of the dielectric increment at pH 6.5 and 7.0 showed strong concentration dependence, indicating the presence of relatively strong dipole-dipole interactions at these pHs. To test if the cluster of charged residues present in the Fab contributes to the mean dipole moment observed for MAb1, additional mutants involving charge mutations in the CDR were investigated. In contrast to MAb1, all of the other MAbs showed significantly reduced pH and concentration dependence of the measured dipole moments and dielectric increments, respectively.The solution pH dependent measured dipole moments of MAb1 appears to be in line with the observed intermolecular interactions and viscosity behavior suggesting that dipole-dipole interaction plays an important role in governing the high concentration solution behavior of this MAb.
Keywords: dielectric relaxation spectroscopy; dipole interactions; high concentration solutions; self-association; short-range interactions
AAPS Connection (2559-2561).