Pharmaceutical Research (v.33, #11)

BDDCS, ECCS and ECCCS are compound disposition classification concepts that aim to streamline, de-risk and speed-up drug development. Although all three systems have the same purpose and are based on classifying drugs into four main categories, they have different backgrounds and contrast in their criteria. Here the details, differences and most important applications of the three systems are reviewed with particular emphasis of their roles for drug discovery and development.
Keywords: BDDCS; drug disposition classification; ECCCS; ECCS; enzyme/transporter interplay

Over the past decade we have witnessed the increasing sophistication of machine learning algorithms applied in daily use from internet searches, voice recognition, social network software to machine vision software in cameras, phones, robots and self-driving cars. Pharmaceutical research has also seen its fair share of machine learning developments. For example, applying such methods to mine the growing datasets that are created in drug discovery not only enables us to learn from the past but to predict a molecule’s properties and behavior in future. The latest machine learning algorithm garnering significant attention is deep learning, which is an artificial neural network with multiple hidden layers. Publications over the last 3 years suggest that this algorithm may have advantages over previous machine learning methods and offer a slight but discernable edge in predictive performance. The time has come for a balanced review of this technique but also to apply machine learning methods such as deep learning across a wider array of endpoints relevant to pharmaceutical research for which the datasets are growing such as physicochemical property prediction, formulation prediction, absorption, distribution, metabolism, excretion and toxicity (ADME/Tox), target prediction and skin permeation, etc. We also show that there are many potential applications of deep learning beyond cheminformatics. It will be important to perform prospective testing (which has been carried out rarely to date) in order to convince skeptics that there will be benefits from investing in this technique.
Keywords: artificial intelligence; deep Learning; drug discovery; machine learning; pharmaceutics

We developed and tested a novel Quantitative Structure-Activity Relationship (QSAR) model to better understand the physicochemical drivers of pulmonary absorption, and to facilitate compound design through improved prediction of absorption. The model was tested using a large array of both existing and newly designed compounds.Pulmonary absorption data was generated using the isolated perfused respiring rat lung (IPRLu) model for 82 drug discovery compounds and 17 marketed drugs. This dataset was used to build a novel QSAR model based on calculated physicochemical properties. A further 9 compounds were used to test the model’s predictive capability.The QSAR model performed well on the 9 compounds in the “Test set” with a predicted versus observed correlation of R2 = 0.85, and >65% of compounds correctly categorised. Calculated descriptors associated with permeability and hydrophobicity positively correlated with pulmonary absorption, whereas those associated with charge, ionisation and size negatively correlated.The novel QSAR model described here can replace routine generation of IPRLu model data for ranking and classifying compounds prior to synthesis. It will also provide scientists working in the field of inhaled drug discovery with a deeper understanding of the physicochemical drivers of pulmonary absorption based on a relevant respiratory compound dataset.
Keywords: intratracheal delivery; isolated perfused lung; physicochemical properties; pulmonary absorption; quantitative structure-activity relationship model

Bioinspired Calcium Phosphate Nanoparticles Featuring as Efficient Carrier and Prompter for Macrophage Intervention in Experimental Leishmaniasis by Mohini Chaurasia; Pankaj K. Singh; Anil K. Jaiswal; Animesh Kumar; Vivek K. Pawar; Anuradha Dube; Sarvesh K. Paliwal; Manish K. Chourasia (2617-2629).
To develop a biocompatible and bioresorbable calcium phosphate (CaP) nanoparticles (NPs) bearing Amphotericin B (AmB) with an aim to provide macrophage specific targeting in visceral leishmaniasis (VL).CaP-AmB-NPs were architectured through emulsion precipitation method. The developed formulation was extensively characterized for various parameters including in-vitro and in-vivo antileishmanial activity. Moreover, plasma pharmacokinetics, tissue biodistribution and toxicity profile were also assessed.Optimized CaP-AmB-NPs exhibited higher entrapment (71.1 ± 6.68%) of AmB. No trend related to higher hemolysis was apparent in the developed formulation as evidenced in commercially available colloidal and liposomal formulations. Cellular uptake of the developed CaP-AmB-NPs was quantified through flow cytometry in J774A.1 cell line, and a 23.90 fold rise in uptake was observed. Fluorescent microscopy also confirmed the time dependent rise in uptake. In-vivo multiple dose toxicity study demonstrated no toxicity upto 5 mg/kg dose of AmB. Plasma kinetics and tissue distribution studies established significantly higher concentration of AmB in group treated with CaP-AmB-NPs in liver and spleen as compared to CAmB, LAmB and AmB suspension group. In-vivo animal experimental results revealed that the CaP-AmB-NPs showed higher splenic parasite inhibition compared to CAmB and LAmB in leishmania parasite infected hamsters.The investigated CaP-AmB-NPs are effective in provoking macrophage mediated uptake and collectively features lower toxicity and offers a suitable replacement for available AmB-formulations for the obliteration of intra-macrophage VL parasite.
Keywords: amphotericin B; calcium phosphate; macrophage targeting; nanoparticles; visceral leishmaniasis

Population Pharmacokinetic Modelling of Morphine, Gabapentin and their Combination in the Rat by Theodoros Papathanasiou; Rasmus Vestergaard Juul; Charlotte Gabel-Jensen; Mads Kreilgaard; Trine Meldgaard Lund (2630-2643).
The combination of morphine and gabapentin seems promising for the treatment of postoperative and neuropathic pain. Despite the well characterised pharmacodynamic interaction, little is known about possible pharmacokinetic interactions. The aim of this study was to evaluate whether co-administration of the two drugs leads to modifications of their pharmacokinetic profiles.The pharmacokinetics of morphine, morphine-3-glucuronide and gabapentin were characterised in rats following subcutaneous injections of morphine, gabapentin or their combination. Non-linear mixed effects modelling was applied to describe the pharmacokinetics of the compounds and possible interactions.The plasma-concentration-time profiles of morphine and gabapentin were best described using a three- and a one-compartment disposition model respectively. Dose dependencies were found for morphine absorption rate and gabapentin bioavailability. Enterohepatic circulation of morphine-3-glucuronide was modelled using an oscillatory model. The combination did not lead to pharmacokinetic interactions for morphine or gabapentin but resulted in an estimated ~33% diminished morphine-3-glucuronide formation.The finding of a lack of pharmacokinetic interaction strengthens the notion that the combination of the two drugs leads to better efficacy in pain treatment due to interaction at the pharmacodynamic level. The interaction found between gabapentin and morphine-3-glucuronide, the latter being inactive, might not have any clinical relevance.
Keywords: drug-drug interactions; enterohepatic circulation; gabapentin; morphine; NONMEM

Exploring Variation in Known Pharmacogenetic Variants and its Association with Drug Response in Different Mexican Populations by Vanessa Gonzalez-Covarrubias; José Jaime Martínez-Magaña; Regina Coronado-Sosa; Beatriz Villegas-Torres; Alma D. Genis-Mendoza; Pablo Canales-Herrerias; Humberto Nicolini; Xavier Soberón (2644-2652).
Information on genetic variants that affect the pharmacokinetics and pharmacodynamics (PK/PD) of drugs in different populations from Mexico is still an ongoing endeavor. Here, we investigate allele frequencies on pharmacogenetic targets in Mexican Mestizos and Natives from three different States and its association with drug efficacy in individuals receiving either anticoagulants or antipsychotic drugs.Natives from three different states and Mestizo patients receiving acenocoumarol or antipsychotics were genotyped using the DMET microarray (Affymetrix).We provide a collection of genetic variants that indicate that there are 3-times more variation than similarities between populations from Mexico and major continental groups. These differences were observed in several relevant targets including ABCB1, SLCO1A1, NAT2, UGTs, TYMS, VKORC1, and NR1I3. Moreover, Mexican Mestizos also showed allele frequency differences when compared to Natives for variants on DPYD, ADH1A, CYP3A4, SLC28A3, and SLC28A1. Significant allele differences also arose among the three Native groups here studied, mostly for transporters of the ABC-binding cassette and the solute carrier gene family. Finally, we explored genotype-drug response associations and pinpointed variants on FMOs (coumarins), and GSTM1 (haloperidol).These findings confirm previous results and further delve into the pharmacogenetics of Mexican populations including different Native groups.
Keywords: antipsychotics; coumarins; Mexican populations; pharmacogenetics

Large Size Microneedle Patch to Deliver Lidocaine through Skin by Himanshu Kathuria; Hairui Li; Jing Pan; Seng Han Lim; Jaspreet Singh Kochhar; Chunyong Wu; Lifeng Kang (2653-2667).
Current topical treatments using lidocaine (LD) for analgesia have limited applications due to their delayed analgesic actions, resulted from slow drug permeation through skin. The aim of this study is to fabricate a large size microneedle (MN) array patch containing LD, with fast onset of action, for the treatment of acute and chronic pain.The MN patch was developed through photolithography and tested for its mechanical characteristics. In vitro and in vivo skin permeation, plasma pharmacokinetics, histology and skin irritation testing have also been performed for the MN patches.The MN have a mechanical strength of 10–30 N and more than 90% of the microneedles on the patch penetrated skin. It was shown that LD permeated through skin within 5 min of patch application. Subsequently, the in vivo skin permeation study using a porcine model showed that LD administrated by the MN patch was able to achieve the therapeutic level locally within 10 min and sustained for 8 h. It shows most of the drug diffuses perpendicularly against skin, with little lateral diffusion. After skin permeation LD remains within skin and unquantifiable amount of LD was found in the plasma of the pigs. Minor skin irritations were observed after 6 h of microneedle contact. However, the skin irritations resolved within 1 day following the removal of MN patch.The large size MN patches showed fast onset and sustained delivery of LD through skin, potentially useful to increase the application scope of topical LD for pain management.
Keywords: drug diffusion; lidocaine; microneedle; pain; skin permeation; transdermal patch

For passive dry powder inhalers (DPIs) entrainment and emission of the aerosolized drug dose depends strongly on device geometry and the patient’s inhalation manoeuvre. We propose a computational method for optimizing the entrainment part of a DPI. The approach assumes that the pulmonary delivery location of aerosol can be determined by the timing of dose emission into the tidal airstream.An optimization algorithm was used to iteratively perform computational fluid dynamic (CFD) simulations of the drug emission of a DPI. The algorithm seeks to improve performance by changing the device geometry. Objectives were to achieve drug emission that was: A) independent of inhalation manoeuvre; B) similar to a target profile. The simulations used complete inhalation flow-rate profiles generated dependent on the device resistance. The CFD solver was OpenFOAM with drug/air flow simulated by the Eulerian-Eulerian method.To demonstrate the method, a 2D geometry was optimized for inhalation independence (comparing two breath profiles) and an early-bolus delivery. Entrainment was both shear-driven and gas-assisted. Optimization for a delay in the bolus delivery was not possible with the chosen geometry.Computational optimization of a DPI geometry for most similar drug delivery has been accomplished for an example entrainment geometry.
Keywords: boundary-condition; cost-function; DPI; entrainment; optimization

General Pharmacokinetic Model for Topically Administered Ocular Drug Dosage Forms by Feng Deng; Veli-Pekka Ranta; Heidi Kidron; Arto Urtti (2680-2690).
In ocular drug development, an early estimate of drug behavior before any in vivo experiments is important. The pharmacokinetics (PK) and bioavailability depend not only on active compound and excipients but also on physicochemical properties of the ocular drug formulation. We propose to utilize PK modelling to predict how drug and formulational properties affect drug bioavailability and pharmacokinetics.A physiologically relevant PK model based on the rabbit eye was built to simulate the effect of formulation and physicochemical properties on PK of pilocarpine solutions and fluorometholone suspensions. The model consists of four compartments: solid and dissolved drug in tear fluid, drug in corneal epithelium and aqueous humor. Parameter values and in vivo PK data in rabbits were taken from published literature.The model predicted the pilocarpine and fluorometholone concentrations in the corneal epithelium and aqueous humor with a reasonable accuracy for many different formulations. The model includes a graphical user interface that enables the user to modify parameters easily and thus simulate various formulations.The model is suitable for the development of ophthalmic formulations and the planning of bioequivalence studies.
Keywords: bioequivalence; drug development; fluorometholone; ocular absorption; pilocarpine

Ursolic Acid Loaded PLGA Nanoparticles: in vitro and in vivo Evaluation to Explore Tumor Targeting Ability on B16F10 Melanoma Cell Lines by Rinku Baishya; Dipak K. Nayak; Deepak Kumar; Samarendu Sinha; Amit Gupta; Shantanu Ganguly; Mita Chatterjee Debnath (2691-2703).
Ursolic acid (UA), a pentacyclic triterpenoid extracted from plants, shows promising inhibitory effect in different tumor bearing cell lines. In the present study we fabricated UA loaded PLGA nanoparticles (UA-NPs) as the drug carrier and thoroughly evaluated in vitro and in vivo the differential tumor targeting effects of UA and UA-NPs in B16F10 melanoma cells.Ursolic acid loaded PLGA nanoparticles were prepared by emulsion solvent evaporation technique and evaluated for particle size, polydispersity, zeta potential and drug release potency. MTT assay as well as flow cytometric and confocal microscopic analyses were done in B16F10 mouse melanoma cell lines. Formulations were labeled with technetium-99m to evaluate the biodistribution and perform scintigraphic imaging studies following intravenous administration in tumor bearing mice model.Single emulsification technique produced smooth spherical nanoparticles of small size with relatively narrow size distribution (154 ± 4.56 nm). On B16F10 cell line, the formulation showed higher cytotoxicity compared to the free drug due to increased in vitro cellular uptake. The formulation was successfully radiolabeled and remained substantially (>90%) stable when incubated (37°C, 6 h) separately in normal saline or freshly collected rat serum or histidine solution. The radiolabeled UA-NPs exhibited slower blood clearance and comparatively high uptake in tumor region as evidenced by biodistribution and scintigraphic studies.The in vitro and in vivo studies have proved the tumor targeting potential of UA-NPs in B16F10 melanoma cell lines.
Keywords: B16F10 cell line; biodistribution; PLGA nanoparticle; radiolabeling; tumor; ursolic acid

A Lower Temperature FDM 3D Printing for the Manufacture of Patient-Specific Immediate Release Tablets by Tochukwu C. Okwuosa; Dominika Stefaniak; Basel Arafat; Abdullah Isreb; Ka-Wai Wan; Mohamed A. Alhnan (2704-2712).
The fabrication of ready-to-use immediate release tablets via 3D printing provides a powerful tool to on-demand individualization of dosage form. This work aims to adapt a widely used pharmaceutical grade polymer, polyvinylpyrrolidone (PVP), for instant on-demand production of immediate release tablets via FDM 3D printing.Dipyridamole or theophylline loaded filaments were produced via processing a physical mixture of API (10%) and PVP in the presence of plasticizer through hot-melt extrusion (HME). Computer software was utilized to design a caplet-shaped tablet. The surface morphology of the printed tablet was assessed using scanning electron microscopy (SEM). The physical form of the drugs and its integrity following an FDM 3D printing were assessed using x-ray powder diffractometry (XRPD), thermal analysis and HPLC. In vitro drug release studies for all 3D printed tablets were conducted in a USP II dissolution apparatus.Bridging 3D printing process with HME in the presence of a thermostable filler, talc, enabled the fabrication of immediate release tablets at temperatures as low as 110°C. The integrity of two model drugs was maintained following HME and FDM 3D printing. XRPD indicated that a portion of the loaded theophylline remained crystalline in the tablet. The fabricated tablets demonstrated excellent mechanical properties, acceptable in-batch variability and an immediate in vitro release pattern.Combining the advantages of PVP as an impeding polymer with FDM 3D printing at low temperatures, this approach holds a potential in expanding the spectrum of drugs that could be used in FDM 3D printing for on demand manufacturing of individualised dosage forms.
Keywords: fused filament fabrication; HME; immediate release; patient-specific

Alterations in P-Glycoprotein Expression and Function Between Macrophage Subsets by Theodore J. Cory; Hui He; Lee C. Winchester; Santosh Kumar; Courtney V. Fletcher (2713-2721).
Macrophages are an important cellular reservoir in HIV, and exist in two phenotypically dissimilar subsets, the pro-inflammatory M1 phenotype, and the anti-inflammatory M2 phenotype. The role of these two subsets is uncertain. We hypothesized that differences in drug efflux transporters exist between the subsets, which would result in altered intracellular drug concentrations between these cells.U937 monocytic cells were polarized to the M1 or M2 phenotype via treatment with interferon-gamma and LPS, or interleukins 4, 13, and LPS, respectively. PGP function was assessed with Hoechst 33342, and expression via western blotting. Intracellular lopinavir was assessed via LC-MS/MS. Data was confirmed with primary monocyte derived macrophages.We observed significant differences in intracellular concentrations of lopinavir, a PGP substrate, with higher concentrations in M1 cells. PGP function and expression was higher in the M2 macrophages. These results were confirmed with primary monocyte derived macrophages.This data shows that there are previously unreported differences in P-glycoprotein expression between macrophage subsets, and suggests that there may be differences for other transporters. These differences can play a role in intracellular drug concentrations in these cells, and may allow for low-level HIV replication.
Keywords: alternatively activated macrophage; classically activated macrophage; Hoechst 33342; P-glycoprotein

Preparation and Evaluation of a Novel Class of Amphiphilic Amines as Antitumor Agents and Nanocarriers for Bioactive Molecules by Isabella Orienti; Mirella Falconi; Gabriella Teti; Mark A. Currier; Jiang Wang; Mitch Phelps; Timothy P. Cripe (2722-2735).
We describe a novel class of antitumor amphiphilic amines (RCn) based on a tricyclic amine hydrophilic head and a hydrophobic linear alkyl tail of variable length.We tested the lead compound, RC16, for cytotoxicity and mechanism of cell death in several cancer cell lines, anti tumor efficacy in mouse tumor models, and ability to encapsulate chemotherapy drugs.These compounds displayed strong cytotoxic activity against cell lines derived from both pediatric and adult cancers. The IC50 of the lead compound, RC16, for normal cells including human keratinocytes, human fibroblasts and human umbilical vein endothelial cells was tenfold higher than for tumor cells. RC16 exhibited significant antitumor effects in vivo using several human xenografts and a metastatic model of murine neuroblastoma by both intravenous and oral administration routes. The amphiphilic character of RC16 triggered a spontaneous molecular self-assembling in water with formation of micelles allowing complexation of Doxorubicin, Etoposide and Paclitaxel. These micelles significantly improved the in vitro antitumor activity of these drugs as the enhancement of their aqueous solubility also improved their biologic availability.RC16 and related amphiphilic amines may be useful as a novel cancer treatment.
Keywords: antitumor activity; encapsulation of bioactive molecules in micelles; formation of micelles in water; novel amphiphilic amines; pharmacokinetics and biodistribution

The current study was designed to develop thiolated-graphene quantum dots (SH-GQDs) as a theranostic nanocarrier and evaluate its potential for the optimal scavenging of reactive oxygen species (ROS) in macrophages.SH-GQDs were prepared by hydrothermal pyrolysis of carbon source (citric acid) in the presence of reduced-glutathione (GSH). Raw264.7 cells were treated with varying concentrations of oxLDL (0.5, 1 and 2 μg/ml) in the presence or absence of SH-GQDs and cells were stained with peroxide-sensitive fluorescent dye (DCFDA). Flow cytometry analysis was performed to investigate the expression of MSR and ATP-binding cassette transporter (ABCA1) after such treatments as the negative control, oxLDL treatment and oxLDL treatment in the presence of either GQDs or SH-GQDs.SH-GQDs had a size ranging from 10 to 30 nm with an average size of 21.3 ± 5.2 nm. The elemental analysis indicated that SH-GQDs are mainly composed of carbon, nitrogen, oxygen and sulfur. The expression levels of ABCA1 in macrophages treated with either LDL or oxLDL were lower than those treated with the media control (the negative control: 100 ± 7.6%; LDL: 82.7 ± 1.2%; and oxLDL: 79.2 ± 1.7%). The level of ABCA1 expression increased as cells were incubated with SH-GQDs (SH-GQDs: 101.5 ± 3.1%). The level of MSR on the surface of macrophages upon being treated with SH-GQDs was lower than those with oxLDL (oxLDL: 112.1 ± 8.8% and SH-GQDs: 91.5 ± 4.2%).The enhancement of lipid efflux and down-regulation of MSR in macrophages by SH-GQDs supported its promising usage as a theranostic nanocarrier to prevent foam cell formation and plaque development.
Keywords: a theranostic carrier; macrophage scavenger receptor (MSR); ROS production; thiolated-graphene quantum dots (SH-GQDs)

Tuning Ciprofloxacin Release Profiles from Liposomally Encapsulated Nanocrystalline Drug by David Cipolla; Huiying Wu; Simon Eastman; Tom Redelmeier; Igor Gonda; Hak-Kim Chan (2748-2762).
In order to attenuate the drug release rate, a single freeze-thaw step was previously shown to convert encapsulated drug into a single nanocrystal within each liposome vesicle. The goal of this study was to alter the nanocrystalline character, and thus the drug encapsulation state and release profile, by addition of surfactant prior to freeze-thaw.A liposomal ciprofloxacin (CFI) formulation was modified by the addition of surfactant and frozen. After thawing, these formulations were characterized in terms of drug encapsulation by centrifugation-filtration, liposome structure by cryo-TEM imaging, vesicle size by dynamic light scattering, and in vitro release (IVR) performance.The addition of increasing levels of polysorbate 20 (0.05 to 0.4%) or Brij 30 (0.05 to 0.3%) to the CFI preparations followed by subsequent freeze-thaw, resulted in a greater proportion of vesicles without drug nanocrystals and reduced the extent of growth of the nanocrystals thus leading to modified release rates including an increase in the ratio of non-encapsulated to sustained release of drug.This study provides another lever to achieve the desired release rate profile from a liposomal formulation by addition of surfactant and subsequent freeze-thaw, and thus may provide a personalized approach to treating patients.
Keywords: in vitro release; liposome; nanocrystal; personalized medicine; surfactant

Optimization of Spray Drying Conditions for Yield, Particle Size and Biological Activity of Thermally Stable Viral Vectors by Daniel A. LeClair; Emily D. Cranston; Zhou Xing; Michael R. Thompson (2763-2776).
This work examines the relevance of viral activity in the optimization of spray drying process parameters for the development of thermally stable vaccine powders. In some instances, the actual active pharmaceutical ingredient (API) is not included in the process optimization as it is deemed too costly to use until the final selection of operating conditions, however, that approach is inappropriate for highly labile biopharmaceutics. We investigate the effects of spray drying parameters on i) yield, ii) particle size and iii) viral vector activity of a mannitol/dextran encapsulated recombinant human type 5 adenoviral vector vaccine, to demonstrate the effects and magnitude of each effect on the three responses, and further show that the API must be included earlier in the optimization.A design of experiments approach was used with response surface methodology (RSM) to optimize parameters including inlet temperature, spray gas flow rate, liquid feed rate and solute concentration in the feed.In general, good conditions for maintaining viral activity led to reduced yield and fewer particles of the desired size. Within the range of parameters tested, the yield varied from 50 to 90%, the percentage of ideally size particles was 10–50%, and the viral vector titre loss was 0.25–4.0 log loss.RSM indicates that the most significant spray drying parameters are the inlet temperature and spray gas flow rate. It was not possible to optimize all three output variables with one set of parameters, indicating that there will only be one dominant criteria for processing which in the case of viral vaccines will likely be viral vector activity.
Keywords: adenovirus; optimization; particle size; process parameters; spray dry; surface response methodology; titre; viral vector; yield

Effect of the Freezing Step in the Stability and Bioactivity of Protein-Loaded PLGA Nanoparticles Upon Lyophilization by Pedro Fonte; Fernanda Andrade; Cláudia Azevedo; João Pinto; Vítor Seabra; Marco van de Weert; Salette Reis; Bruno Sarmento (2777-2793).
The freezing step in lyophilization is the most determinant for the quality of biopharmaceutics. Using insulin as model of therapeutic protein, our aim was to evaluate the freezing effect in the stability and bioactivity of insulin-loaded PLGA nanoparticles. The performance of trehalose, sucrose and sorbitol as cryoprotectants was evaluated.Cryoprotectants were co-encapsulated with insulin into PLGA nanoparticles and lyophilized using an optimized cycle with freezing at −80°C, in liquid nitrogen, or ramped cooling at −40°C. Upon lyophilization, the stability of protein structure and in vivo bioactivity were assessed.Insulin was co-encapsulated with cryoprotectants resulting in particles of 243–394 nm, zeta potential of −32 to −35 mV, and an association efficiency above 90%. The cryoprotectants were crucial to mitigate the freezing stresses and better stabilize the protein. The insulin structure maintenance was evident and close to 90%. Trehalose co-encapsulated insulin-loaded PLGA nanoparticles demonstrated enhanced hypoglycemic effect, comparatively to nanoparticles without cryoprotectant and added with trehalose, due to a superior insulin stabilization and bioactivity.The freezing process may be detrimental to the structure of protein loaded into nanoparticles, with negative consequences to bioactivity. The co-encapsulation of cryoprotectants mitigated the freezing stresses with benefits to protein bioactivity.
Keywords: cryoprotectant; freezing; insulin; lyophilization; PLGA nanoparticles

Computational Screening of Drug Solvates by Christoph Loschen; Andreas Klamt (2794-2804).
Solvates are mainly undesired by-products during the pharmaceutical development of new drugs. In addition, solvate formation may also distort solubility measurements. The presented study introduces a simple computational approach that allows for the identification of drug solvent pairs which most likely form crystalline solid phases.The mixing enthalpy as a measure for drug-solvent complementarity is obtained by computational liquid phase thermodynamics (COSMO-RS theory). In addition a few other simple descriptors were taking into account describing the shape and topology of the drug and the solvent. Using an extensive dataset of drug solvent pairs a simple and statistically robust model is developed which allows for a rough assessment of a solvent’s ability to form a solvate.Similar to the related issue of cocrystal screening, the mixing (or excess) enthalpy of the subcooled liquid mixture of the drug-solvent pair proves to be an important quantity controlling solvate formation. Due to the fact that many solvates form inclusion compounds, the solvent shape is another important factor influencing solvate formation. Solvates forming channel-like voids in the solid state are predicted less well.The approach ranks any drug-solvent pair that forms a solvate before any non-solvate by a probability of about 81% (AUC = 0.81), giving a significant advantage over any trial and error approach. Hence it can help to identify suitable solvent candidates early in the drug development process.
Keywords: co-crystallization; computer simulation; solubility; solvate; thermodynamics

To verify previously reported findings for the European Medicines Agency’s method for Average Bioequivalence with Expanding Limits (ABEL) for assessing highly variable drugs and to extend the assessment for other replicate designs in a wide range of sample sizes and CVs. To explore the properties of a new modified method which maintains the consumer risk ≤0.05 in all cases.Monte-Carlo simulations of three different replicate designs covering a wide range of sample sizes and intra-subject variabilities were performed.At the switching variability of CV wR 30% the consumer risk is substantially inflated to up to 9.2%, which translates into a relative increase of up to 84%. The critical region of inflated type I errors ranges approximately from CV wR 25 up to 45%. The proposed method of iteratively adjusting α maintains the consumer risk at the desired level of ≤5% independent from design, variability, and sample size.Applying the European Medicines Agency’s ABEL method at the nominal level of 0.05 inflates the type I error to an unacceptable degree, especially close to a CV wR of 30%. To control the type I error nominal levels ≤0.05 should be employed. Iteratively adjusting α is suggested to find optimal levels of the test.
Keywords: bioequivalence; European Medicines Agency; highly variable drugs; Monte-Carlo simulation; reference-scaling

Folate-Mediated Targeted Delivery of Combination Chemotherapeutics Loaded Reduced Graphene Oxide for Synergistic Chemo-Photothermal Therapy of Cancers by Raj Kumar Thapa; Yongjoo Choi; Jee-Heon Jeong; Yu Seok Youn; Han-Gon Choi; Chul Soon Yong; Jong Oh Kim (2815-2827).
Larger surface area for drug incorporation and superior optical activity makes reduced graphene oxide (rGO) a suitable drug carrier for combination chemotherapeutics delivery. And folate receptors are potential mediators for cancer targeted delivery. This study mainly aimed to prepare irinotecan (IRI)- and docetaxel (DOC)-loaded, folate (FA)-conjugated rGO (FA-P407-rGO/ID) for synergistic cancer therapy.FA-P407-rGO/ID was prepared as aqueous dispersion. Characterization was performed using high performance liquid chromatography (HPLC), transmission electron microscopy (TEM), atomic force microscopy (AFM), ultraviolet/visible spectroscopy, fourier transform infrared spectroscopy (FTIR) and drug release. In vitro cellular studies were performed using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS), fluorescence-activated cell sorting (FACS) and western blot analyses.Our results revealed successful preparation of stable FA-P407-rGO/ID formulation with enhanced drug release profiles in acidic microenvironment. In vitro cytotoxicity of the formulation on folate receptor-expressing human mammary carcinoma (MCF-7) cells was higher than that when free IRI/DOC combination (ID) was used; such increased cytotoxicity was not observed in folate receptor-negative hepatocellular carcinoma (HepG2) cells. Cellular uptake of FA-P407-rGO/ID in MCF-7 cells was higher than in HepG2 cells. Further, FACS and western blot analysis revealed better apoptotic effects of the formulation in MCF-7 cells than in HepG2 cells, suggesting the important role of folate receptors for targeted chemotherapy delivery to cancer cells. Near infrared irradiation further enhanced the apoptotic effect in cancer cells, resulting from the photothermal effects of rGO.Hence, FA-P407-rGO/ID can be considered as a potential formulation for folate-targeted chemo-photothermal therapy in cancer cells.
Keywords: combination chemotherapy; docetaxel; folic acid; irinotecan; reduced graphene oxide

Emodin-Loaded PLGA-TPGS Nanoparticles Combined with Heparin Sodium-Loaded PLGA-TPGS Nanoparticles to Enhance Chemotherapeutic Efficacy Against Liver Cancer by Hongyan Liu; Hong Xu; Chenghong Zhang; Meng Gao; Xiaoguang Gao; Chuchu Ma; Li Lv; Dongyan Gao; Sa Deng; Changyuan Wang; Yan Tian (2828-2843).
Heparin sodium (HS)-loaded polylactic-co-glycolic acid-D-α-tocopheryl polyethylene glycol 1000 succinate (PLGA-TPGS) nanoparticles (HPTNs) were prepared as a sustained and targeting delivery carrier and combined with emodin (EMO)-loaded PLGA-TPGS nanoparticles (EPTNs), which were investigated previously to form a combination therapy system for the treatment of liver cancer.To assess cellular uptake and evaluate the liver-targeting capacity by analyzing the drug concentrations and frozen slices, HS/eosin-loaded PLGA-TPGS nanoparticles, HS/fluorescein- loaded PLGA-TPGS nanoparticles and EMO/C6-loaded PLGA-TPGS nanoparticles, which contained eosin, fluorescein and C6 as fluorescent probes, respectively, were also prepared. All of these nanoparticles were characterized in terms of their size, size distribution, surface charge, drug loading, encapsulation efficiency, in vitro release profile and cellular uptake. The apoptosis of HepG2 cells induced by EPTNs in combination with HPTNs was determined by Annexin V-FITC staining and PI labelling.Transmission electron microscopy indicated that these nanoparticles were stably dispersed spheres with sizes ranging from 100 to 200 nm. The results demonstrated that fluorescent nanoparticles were internalized into HepG2 and HCa-F cells efficiently and had improved liver-targeting properties. The combination of EPTNs and HPTNs effectively inhibited cell growth in vitro and had a remarkable synergistic anticancer effect in vivo. EPTNs combined with HPTNs induced HepG2 cell apoptosis with synergistic effects. The liver H&E slice images of a hepatocarcinogenic mouse model indicated that EPTNs in combination with HPTNs significantly suppressed tumour growth in vivo.The research suggests that the combination therapy system of EPTNs and HPTNs could be a new direction for liver cancer therapy.
Keywords: combination therapy; emodin; heparin sodium; liver cancer; PLGA-TPGS nanoparticles

Erratum to: Characterization of Pharmacokinetics in the Göttingen Minipig with Reference Human Drugs: An In Vitro and In Vivo Approach by Floriane Lignet; Eva Sherbetjian; Nicole Kratochwil; Russell Jones; Claudia Suenderhauf; Michael B. Otteneder; Thomas Singer; Neil Parrott (2844-2844).

Erratum to: Targeting of Micelles and Liposomes Loaded with the Pro-Apoptotic Drug, NCL-240, into NCI/ADR-RES Cells in a 3D Spheroid Model by Bhushan S. Pattni; Srikar G. Nagelli; Bhawani Aryasomayajula; Pranali P. Deshpande; Abhijit Kulkarni; William C. Hartner; Ganesh Thakur; Alexei Degterev; Vladimir P. Torchilin (2845-2846).