Pharmaceutical Research (v.33, #5)

Microneedles: A New Frontier in Nanomedicine Delivery by Eneko Larrañeta; Maelíosa T. C. McCrudden; Aaron J. Courtenay; Ryan F. Donnelly (1055-1073).
This review aims to concisely chart the development of two individual research fields, namely nanomedicines, with specific emphasis on nanoparticles (NP) and microparticles (MP), and microneedle (MN) technologies, which have, in the recent past, been exploited in combinatorial approaches for the efficient delivery of a variety of medicinal agents across the skin. This is an emerging and exciting area of pharmaceutical sciences research within the remit of transdermal drug delivery and as such will undoubtedly continue to grow with the emergence of new formulation and fabrication methodologies for particles and MN. Firstly, the fundamental aspects of skin architecture and structure are outlined, with particular reference to their influence on NP and MP penetration. Following on from this, a variety of different particles are described, as are the diverse range of MN modalities currently under development. The review concludes by highlighting some of the novel delivery systems which have been described in the literature exploiting these two approaches and directs the reader towards emerging uses for nanomedicines in combination with MN.
Keywords: drug delivery; microneedles; microparticles; nanomedicine; nanoparticles; vaccines

A new Strategy to Improve Drug Delivery to the Maxillary Sinuses: The Frequency Sweep Acoustic Airflow by Amira El Merhie; Laurent Navarro; Xavier Delavenne; Lara Leclerc; Jérémie Pourchez (1074-1084).
Enhancement of intranasal sinus deposition involves nebulization of a drug superimposed by an acoustic airflow. We investigated the impact of fixed frequency versus frequency sweep acoustic airflow on the improvement of aerosolized drug penetration into maxillary sinuses.Fixed frequency and frequency sweep acoustic airflow were generated using a nebulizing system of variable frequency. The effect of sweep cycle and intensity variation was studied on the intranasal sinus deposition. We used a nasal replica created from CT scans using 3D printing. Sodium fluoride and gentamicin were chosen as markers.Studies performed using fixed frequency acoustic airflow showed that each of maxillary sinuses of the nasal replica required specific frequency for the optimal aerosol deposition. Intranasal sinus drug deposition experiments under the effect of the frequency sweep acoustic airflow showed an optimal aerosol deposition into both maxillary sinus of the nasal replica. Studies on the effect of the duration of the sweep cycle showed that the shorter the cycle the better the deposition.We demonstrate the benefit of frequency sweep acoustic airflow on drug deposition into maxillary sinuses. However further in vivo studies have to be conducted since delivery rates cannot be obviously determined from a nasal replica.
Keywords: fixed frequency; frequency sweep acoustic airflow; intranasal sinus deposition; sweep cycle

Budesonide Loaded PLGA Nanoparticles for Targeting the Inflamed Intestinal Mucosa—Pharmaceutical Characterization and Fluorescence Imaging by Hussain Ali; Benno Weigmann; Eva-Maria Collnot; Saeed Ahmad Khan; Maike Windbergs; Claus-Michael Lehr (1085-1092).
The purpose of this study was to evaluate the specifically targeted efficiency of budesonide loaded PLGA nanoparticles for the treatment of inflammatory bowel disease (IBD).The nanoparticles were prepared by an oil/water (O/W) emulsion evaporation technique. The nanoparticles were characterized for their size, shape and in vitro drug release profile. Solid state characterization was carried out by differential scanning calorimetry (DSC) and X-ray Power diffraction (XPRD). In order to evaluate the targeted efficiency of nanoparticles, a particle localization study in the healthy and in the inflamed colon was determined in vivo. These data were complemented by cryo-sections.Nanoparticles were 200 ± 05 nm in size with a smooth and spherical shape. The encapsulation efficiency was around 85 ± 3.5%, which was find-out by both, direct and indirect methods. Release of budesonide from the nanoparticles showed a biphasic release profile with an initial burst followed by sustained release. XPRD data revealed that the drug in the polymer matrix existed in crystalline state. Nanoparticles accumulation in inflamed tissues was evaluated by in-vivo imaging system and it was found that particles are accumulated in abundance at the site of inflammation when compared to the healthy group.The study demonstrates that the budesonide loaded PLGA nanoparticles are an efficient delivery system for targeted drug delivery to the inflamed intestinal mucosa.
Keywords: budesonide; colitis; DSC; nanoparticles; oxazolone; sustained drug release; XRD

A Pharmacokinetic-Pharmacodynamic Model of Morphine Exposure and Subsequent Morphine Consumption in Postoperative Pain by Rasmus Vestergaard Juul; Joakim Nyberg; Trine Meldgaard Lund; Sten Rasmussen; Mads Kreilgaard; Lona Louring Christrup; Ulrika S. H. Simonsson (1093-1103).
To characterize the pharmacokinetic-pharmacodynamic (PK-PD) relationship between exposure of morphine and subsequent morphine consumption and to develop simulation tools for model validation.Dose, formulation and time of morphine administration was available from a published study in 63 patients receiving intravenous, oral immediate release or oral controlled release morphine on request after hip surgery. The PK-PD relationship between predicted exposure of morphine and morphine consumption was modeled using repeated time to event (RTTE) modeling in NONMEM. To validate the RTTE model, a visual predictive check method was developed with simulated morphine consumption given the exposure of preceding morphine administration.The probability of requesting morphine was found to be significantly related to the exposure of morphine as well as night/day. Oral controlled release morphine was more effective than intravenous and oral immediate release formulations at equivalent average concentrations. Maximum effect was obtained for 8 h by oral controlled release doses ≥ 15 mg, where probability of requesting a new dose was reduced to 20% for a typical patient.This study demonstrates the first quantitative link between exposure of morphine and subsequent morphine consumption and introduces an efficient visual predictive check approach with simulation of adaptive dosing.
Keywords: non-linear mixed effects modeling; opioid consumption; pharmacokinetics-pharmacodynamics; postoperative pain; repeated time to event

This study was aimed at developing a new active loading method to stably encapsulate staurosporine (STS), a water insoluble drug, into lipid-based nanoparticles (LNPs) for drug targeting to tumors.A limited amount of DMSO was included during the active loading process to prevent precipitation and facilitate the loading of insoluble STS into the aqueous core of a LNP. The drug loading kinetics under various conditions was studied and the STS-LNPs were characterized by size, drug-to-lipid ratio, drug release kinetics and in vitro potency. The antitumor efficacy of the STS-LNPs was compared with free STS in a mouse model.The drug loading efficiency reached 100% within 15 min of incubation at a drug-to-lipid ratio of 0.31 (mol) via an ammonium gradient. STS formed nano-aggregates inside the aqueous core of the LNPs and was stably retained upon storage and in the presence of serum. A 3-fold higher dose of the STS-LNPs could be tolerated by BALB/c mice compared with free STS, leading to nearly complete growth inhibition of a multidrug resistant breast tumor, while free STS only exhibited moderate activity.This simple and efficient drug loading method produced a stable LNP formulation for STS that was effective for cancer treatment.
Keywords: Multidrug resistant cancer; Liposome; Active loading; Staurosporine; Water insoluble drug

Simulation-Based Evaluation of PK/PD Indices for Meropenem Across Patient Groups and Experimental Designs by Anders N. Kristoffersson; Pascale David-Pierson; Neil J. Parrott; Olaf Kuhlmann; Thierry Lave; Lena E. Friberg; Elisabet I. Nielsen (1115-1125).
Antibiotic dose predictions based on PK/PD indices rely on that the index type and magnitude is insensitive to the pharmacokinetics (PK), the dosing regimen, and bacterial susceptibility. In this work we perform simulations to challenge these assumptions for meropenem and Pseudomonas aeruginosa.A published murine dose fractionation study was replicated in silico. The sensitivity of the PK/PD index towards experimental design, drug susceptibility, uncertainty in MIC and different PK profiles was evaluated.The previous murine study data were well replicated with fT > MIC selected as the best predictor. However, for increased dosing frequencies fAUC/MIC was found to be more predictive and the magnitude of the index was sensitive to drug susceptibility. With human PK fT > MIC and fAUC/MIC had similar predictive capacities with preference for fT > MIC when short t1/2 and fAUC/MIC when long t1/2.A longitudinal PKPD model based on in vitro data successfully predicted a previous in vivo study of meropenem. The type and magnitude of the PK/PD index were sensitive to the experimental design, the MIC and the PK. Therefore, it may be preferable to perform simulations for dose selection based on an integrated PK-PKPD model rather than using a fixed PK/PD index target.
Keywords: antibiotic; dose selection; meropenem; pharmacometric; pseudomonas aeruginosa

A critical Examination of the Phenomenon of Bonding Area - Bonding Strength Interplay in Powder Tableting by Frederick Osei-Yeboah; Shao-Yu Chang; Changquan Calvin Sun (1126-1132).
Although the bonding area (BA) and bonding strength (BS) interplay is used to explain complex tableting behaviors, it has never been experimentally proven. The purpose of this study is to unambiguously establish the distinct contributions of each by decoupling the contributions from BA and BS.To modulate BA, a Soluplus® powder was compressed into tablets at different temperatures and then broken following equilibration at 25°C. To modulate BS, tablets were equilibrated at different temperatures. To simultaneously modulate BA and BS, both powder compression and tablet breaking test were carried out at different temperatures.Lower tablet tensile strength is observed when the powder is compressed at a lower temperature but broken at 25°C. This is consistent with the increased resistance to polymer deformation at lower temperatures. When equilibrated at different temperatures, the tensile strength of tablets prepared under identical conditions increases with decreasing storage temperature, indicating that BS is higher at a lower temperature. When powder compression and tablet breaking are carried out at the same temperature, the profile with a maximum tensile strength at 4°C is observed due to the BA-BS interplay.By systematically varying temperature during tablet compression and breaking, we have experimentally demonstrated the phenomenon of BA-BS interplay in tableting.
Keywords: bonding area; bonding strength; compaction; powder; tableting

Pharmacokinetic/Pharmacodynamic Relationship of Gabapentin in a CFA-induced Inflammatory Hyperalgesia Rat Model by Malte Selch Larsen; Ron Keizer; Gordon Munro; Arne Mørk; René Holm; Rada Savic; Mads Kreilgaard (1133-1143).
Gabapentin displays non-linear drug disposition, which complicates dosing for optimal therapeutic effect. Thus, the current study was performed to elucidate the pharmacokinetic/pharmacodynamic (PKPD) relationship of gabapentin’s effect on mechanical hypersensitivity in a rat model of CFA-induced inflammatory hyperalgesia.A semi-mechanistic population-based PKPD model was developed using nonlinear mixed-effects modelling, based on gabapentin plasma and brain extracellular fluid (ECF) time-concentration data and measurements of CFA-evoked mechanical hyperalgesia following administration of a range of gabapentin doses (oral and intravenous).The plasma/brain ECF concentration-time profiles of gabapentin were adequately described with a two-compartment plasma model with saturable intestinal absorption rate (K m  = 44.1 mg/kg, V max  = 41.9 mg/h∙kg) and dose-dependent oral bioavailability linked to brain ECF concentration through a transit compartment. Brain ECF concentration was directly linked to a sigmoid E max function describing reversal of hyperalgesia (EC 50, plasma  = 16.7 μg/mL, EC 50, brain  = 3.3 μg/mL).The proposed semi-mechanistic population-based PKPD model provides further knowledge into the understanding of gabapentin’s non-linear pharmacokinetics and the link between plasma/brain disposition and anti-hyperalgesic effects. The model suggests that intestinal absorption is the primary source of non-linearity and that the investigated rat model provides reasonable predictions of clinically effective plasma concentrations for gabapentin.
Keywords: brain; gabapentin; pain; PKPD modelling; rat

Stabilization of Live Attenuated Influenza Vaccines by Freeze Drying, Spray Drying, and Foam Drying by Phillip M. Lovalenti; Jeff Anderl; Luisa Yee; Van Nguyen; Behnaz Ghavami; Satoshi Ohtake; Atul Saxena; Thomas Voss; Vu Truong-Le (1144-1160).
The goal of this research is to develop stable formulations for live attenuated influenza vaccines (LAIV) by employing the drying methods freeze drying, spray drying, and foam drying.Formulated live attenuated Type-A H1N1 and B-strain influenza vaccines with a variety of excipient combinations were dried using one of the three drying methods. Process and storage stability at 4, 25 and 37°C of the LAIV in these formulations was monitored using a TCID50 potency assay. Their immunogenicity was also evaluated in a ferret model.The thermal stability of H1N1 vaccine was significantly enhanced through application of unique formulation combinations and drying processes. Foam dried formulations were as much as an order of magnitude more stable than either spray dried or freeze dried formulations, while exhibiting low process loss and full retention of immunogenicity. Based on long-term stability data, foam dried formulations exhibited a shelf life at 4, 25 and 37°C of >2, 1.5 years and 4.5 months, respectively. Foam dried LAIV Type-B manufactured using the same formulation and process parameters as H1N1 were imparted with a similar level of stability.Foam drying processing methods with appropriate selection of formulation components can produce an order of magnitude improvement in LAIV stability over other drying methods.
Keywords: Attenuated; Drying; Influenza; Stability; Vaccine

Sugar-Grafted Cyclodextrin Nanocarrier as a “Trojan Horse” for Potentiating Antibiotic Activity by Min Li; Koon Gee Neoh; Liqun Xu; Liang Yuan; David Tai Leong; En-Tang Kang; Kim Lee Chua; Li Yang Hsu (1161-1174).
The use of “Trojan Horse” nanocarriers for antibiotics to enhance the activity of antibiotics against susceptible and resistant bacteria is investigated.Antibiotic carriers (CD-MAN and CD-GLU) are prepared from β-cyclodextrin grafted with sugar molecules (D-mannose and D-glucose, respectively) via azide-alkyne click reaction. The sugar molecules serve as a chemoattractant enticing the bacteria to take in higher amounts of the antibiotic, resulting in rapid killing of the bacteria.Three types of hydrophobic antibiotics, erythromycin, rifampicin and ciprofloxacin, are used as model drugs and loaded into the carriers. The minimum inhibitory concentration of the antibiotics in the CD-MAN-antibiotic and CD-GLU-antibiotic complexes for Gram-negative Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii strains, and a number of Gram-positive Staphylococcus aureus strains, including the methicillin-resistant strains (MRSA), are reduced by a factor ranging from 3 to >100. The CD-MAN-antibiotic complex is also able to prolong the stability of the loaded antibiotic and inhibit development of intrinsic antibiotic resistance in the bacteria.These non-cytotoxic sugar-modfied nanocarriers can potentiate the activity of existing antibiotics, especially against multidrug-resistant bacteria, which is highly advantageous in view of the paucity of new antibiotics in the pipeline.
Keywords: antibacterial; antibiotic nanocarrier; glucose; mannose; β-cyclodextrin

Drug Release from ß-Cyclodextrin Complexes and Drug Transfer into Model Membranes Studied by Affinity Capillary Electrophoresis by Kinda A. Darwish; Yahya Mrestani; Hans-Hermann Rüttinger; Reinhard H. H. Neubert (1175-1181).
Is to characterize the drug release from the ß-cyclodextrin (ß-CD) cavity and the drug transfer into model membranes by affinity capillary electrophoresis. Phospholipid liposomes with and without cholesterol were used to mimic the natural biological membrane.The interaction of cationic and anionic drugs with ß-CD and the interaction of the drugs with liposomes were detected separately by measuring the drug mobility in ß-CD containing buffer and liposome containing buffer; respectively. Moreover, the kinetics of drug release from ß-CD and its transfer into liposomes with or without cholesterol was studied by investigation of changes in the migration behaviours of the drugs in samples, contained drug, ß-CD and liposome, at 1:1:1 molar ratio at different time intervals; zero time, 30 min, 1, 2, 4, 6, 8, 10 and 24 h. Lipophilic drugs such as propranolol and ibuprofen were chosen for this study, because they form complexes with ß-CD.The mobility of the both drug liposome mixtures changed with time to a final state. For samples of liposomal membranes with cholesterol the final state was faster reached than without cholesterol.The study confirmed that the drug release from the CD cavity and its transfer into the model membrane was more enhanced by the competitive displacement of the drug from the ß-CD cavity by cholesterol, the membrane component. The ACE method here developed can be used to optimize the drug release from CD complexes and the drug transfer into model membranes.
Keywords: affinity capillary electrophoresis; cyclodextrin complexes; drug release; drug transfer; liposome model membrane

The encapsulation of pancreatic β-cells in biocompatible matrix has generated great interest in diabetes treatment. Our work has shown improved microcapsules when incorporating the bile acid ursodeoxycholic acid (UDCA), in terms of morphology and cell viability although cell survival remained low. Thus, the study aimed at incorporating the polyelectrolytes polyallylamine (PAA) and poly-l-ornithine (PLO), with the polymer sodium alginate (SA) and the hydrogel ultrasonic gel (USG) with UDCA and examined cell viability and functionality post microencapsulation.Microcapsules without (control) and with UDCA (test) were produced using 1% PLO, 2.5% PAA, 1.8% SA and 4.5% USG. Pancreatic β-cells were microencapsulated and the microcapsules’ morphology, surface components, cellular and bile acid distribution, osmotic and mechanical stability as well as biocompatibilities, insulin production, bioenergetics and the inflammatory response were tested.Incorporation of UDCA at 4% into a PLO-PAA-SA formulation system increased cell survival (p < 0.01), insulin production (p < 0.01), reduced the inflammatory profile (TNF-α, IFN-ϒ, IL-6 and IL-1β; p < 0.01) and improved the microcapsule physical and mechanical strength (p < 0.01).β-cell microencapsulation using 1% PLO, 2.5% PAA, 1.8% SA, 4.5% USG and the bile acid UDCA (4%) has good potential in cell transplantation and diabetes treatment.
Keywords: artificial cell microencapsulation; bioenergetics; biomaterials; pancreatic β-cells; ursodeoxycholic acid

Nanoparticle Attachment to Erythrocyte Via the Glycophorin A Targeted ERY1 Ligand Enhances Binding without Impacting Cellular Function by Kaustuv Sahoo; Rangika S. Hikkaduwa Koralege; Nicholas Flynn; Samyukta Koteeswaran; Peter Clark; Steve Hartson; Jing Liu; Joshua D. Ramsey; Carey Pope; Ashish Ranjan (1191-1203).
Nanoparticle (NP) attachment to biocompatible secondary carriers such as red blood cell (RBC) can prolong blood residence time of drug molecules and help create next-generation nanotherapeutics. However, little is known about the impact of RBC-targeted NPs on erythrocyte function.The objectives of this study were to develop and characterize in vitro a novel poly-L-lysine (PLL) and polyethylene glycol (PEG) copolymer-based NP containing fluorescent-tagged bovine serum albumin (BSA), and conjugated with ERY1, a 12 amino acid peptide with high affinity for the RBC membrane protein glycophorin A (ENP).Confocal and flow cytometry data suggest that ENPs efficiently and irreversibly bind to RBC, with approximately 70% of erythrocytes bound after 24 h in a physiologic flow loop model compared to 10% binding of NPs without ERY1. Under these conditions, synthesized ENPs were not toxic to the RBCs. The rheological parameters at the applied shear. (0–15 Pa) were not influenced by ENP attachment to the RBCs. However, at high concentration, the strong affinity of ENPs to the glycophorin-A reduced the deformability of the RBC.ENPs can be efficiently attached to the RBCs without adversely affecting cellular function, and this may potentially enhance circulatory half-life of drug molecules.
Keywords: ERY1-ligand; glycophorin A targeting; nanoparticle; red blood cell; rheology

To evaluate an alternative in vitro system which can provide more quantitatively accurate drug drug interaction (DDI) prediction for 10 protein kinase inhibitors for which DDI risk was over-predicted by inhibition data generated in human liver microsomes (HLM).Three cryopreserved human hepatocyte (hHEP) systems: 1) plated hHEPs; 2) hHEPs suspended in Dulbecco’s Modified Eagle Medium (DMEM) and 3) hHEPs suspended in human plasma (plasma hHEPs) were developed to detect CYP3A time dependent inhibition, and the static mechanistic model was used to predict clinical outcomes.A general trend was observed in the CYP3A inactivation potency (k inact /K I, app ) as HLM > plated > DMEM ≥ plasma hHEPs. Using the static mechanistic model, DDIs predicted using parameters estimated from plated, DMEM and plasma hHEPs had 84, 74 and 95% accuracy (out of 19 clinical interaction studies) within 2-fold of the reported interaction, respectively. They demonstrated significant improvement compared to the DDIs predicted using parameters estimated from HLMs where 58% accuracy was obtained.Based on 19 DDIs, plasma hHEPs demonstrate a more reliable clinical DDI prediction for 10 protein kinase inhibitors and prototypical CYP3A time dependent inhibitors.
Keywords: CYP3A; drug–drug interaction; kinase inhibitors; prediction; time dependent inhibition

Multimodal Dispersion of Nanoparticles: A Comprehensive Evaluation of Size Distribution with 9 Size Measurement Methods by Fanny Varenne; Ali Makky; Mireille Gaucher-Delmas; Frédéric Violleau; Christine Vauthier (1220-1234).
Evaluation of particle size distribution (PSD) of multimodal dispersion of nanoparticles is a difficult task due to inherent limitations of size measurement methods. The present work reports the evaluation of PSD of a dispersion of poly(isobutylcyanoacrylate) nanoparticles decorated with dextran known as multimodal and developed as nanomedecine.The nine methods used were classified as batch particle i.e. Static Light Scattering (SLS) and Dynamic Light Scattering (DLS), single particle i.e. Electron Microscopy (EM), Atomic Force Microscopy (AFM), Tunable Resistive Pulse Sensing (TRPS) and Nanoparticle Tracking Analysis (NTA) and separative particle i.e. Asymmetrical Flow Field-Flow Fractionation coupled with DLS (AsFlFFF) size measurement methods.The multimodal dispersion was identified using AFM, TRPS and NTA and results were consistent with those provided with the method based on a separation step prior to on-line size measurements. None of the light scattering batch methods could reveal the complexity of the PSD of the dispersion.Difference between PSD obtained from all size measurement methods tested suggested that study of the PSD of multimodal dispersion required to analyze samples by at least one of the single size particle measurement method or a method that uses a separation step prior PSD measurement.
Keywords: light scattering; microscopy; nanoparticle tracking analysis; particle size distribution; tunable resistive pulse sensing

Exploration of Antiemetics for Osteoporosis Therapy-Induced Nausea and Vomiting Using PET Molecular Imaging Analysis to Gastrointestinal Pharmacokinetics by Tomotaka Shingaki; Yumiko Katayama; Takayoshi Nakaoka; Tadayuki Takashima; Kayo Onoe; Takashi Okauchi; Emi Hayashinaka; Yasuhiro Wada; Yilong Cui; Yasuyoshi Watanabe (1235-1248).
To select appropriate antiemetics relieving teriparatide-induced nausea and vomiting during osteoporosis treatment using PET molecular imaging and pharmacokinetic analysis.Rats were pretreated with subcutaneous teriparatide, followed by oral administration of antiemetics with different pharmacological effects. The pharmacokinetics of antiemetics were assessed by oral administration of 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG) under free moving conditions in vivo. The effect of teriparatide on the permeability of Caco-2 cell membranes to [18F]FDG was assessed in vitro. The effects of antiemetics on teriparatide-induced suppression of gastrointestinal motility in vivo was assayed by positron emission tomography (PET) using orally administered [18F]FDG.Teriparatide delayed the time-radioactivity profile of [18F]FDG in blood and significantly reduced its absorption rate constant (k a ), determined from non-compartmental analysis, to 60% of control. In contrast, co-administration of granisetron or mosapride restored the time-radioactivity profile and k a of [18F]FDG to control levels. Teriparatide had no effect on Caco-2 membrane permeability to [18F]FDG. Pharmacokinetic PET imaging data analysis quantitatively showed the pharmacological effects of teriparatide-induced suppression of upper gastrointestinal motility and its restoration by granisetron and mosapride.Teriparatide-induced abdominal discomfort might be attributed to GI motility, and PET imaging analysis is a useful tool to for the selection of appropriate antiemetics.
Keywords: antiemetics; gastrointestinal motility; osteoporosis; positron emission tomography (PET); teriparatide

Insights into Spray Development from Metered-Dose Inhalers Through Quantitative X-ray Radiography by Nicholas Mason-Smith; Daniel J. Duke; Alan L. Kastengren; Peter J. Stewart; Daniela Traini; Paul M. Young; Yang Chen; David A. Lewis; Julio Soria; Daniel Edgington-Mitchell; Damon Honnery (1249-1258).
Typical methods to study pMDI sprays employ particle sizing or visible light diagnostics, which suffer in regions of high spray density. X-ray techniques can be applied to pharmaceutical sprays to obtain information unattainable by conventional particle sizing and light-based techniques.We present a technique for obtaining quantitative measurements of spray density in pMDI sprays. A monochromatic focused X-ray beam was used to perform quantitative radiography measurements in the near-nozzle region and plume of HFA-propelled sprays.Measurements were obtained with a temporal resolution of 0.184 ms and spatial resolution of 5 μm. Steady flow conditions were reached after around 30 ms for the formulations examined with the spray device used. Spray evolution was affected by the inclusion of ethanol in the formulation and unaffected by the inclusion of 0.1% drug by weight. Estimation of the nozzle exit density showed that vapour is likely to dominate the flow leaving the inhaler nozzle during steady flow.Quantitative measurements in pMDI sprays allow the determination of nozzle exit conditions that are difficult to obtain experimentally by other means. Measurements of these nozzle exit conditions can improve understanding of the atomization mechanisms responsible for pMDI spray droplet and particle formation.
Keywords: pressurised metered dose inhaler; radiography; synchrotron radiation; X-ray

New Perspectives for Fixed Dose Combinations of Poorly Water-Soluble Compounds: a Case Study with Ezetimibe and Lovastatin by Manoela K. Riekes; Axel Engelen; Bernard Appeltans; Patrick Rombaut; Hellen K. Stulzer; Guy Van den Mooter (1259-1275).
Aiming to improve the dissolution rate of ezetimibe (EZE) and lovastatin (LOV) in a fixed dose combination (FDC), co-amorphous systems and ternary solid dispersions were prepared by quench cooling and spray drying, respectively.Formulations were characterized through X-ray diffraction, modulated differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy and laser diffraction, and evaluated by ‘in vitro’ dissolution. Stability studies were conducted at different conditions during 30 days with the ternary solid dispersion composed of 75% of Soluplus® (ELS 1:1 75%).Single phase co-amorphous systems made up of the pure drugs were not able to increase the dissolution rate of EZE and LOV. However, ternary solid dispersions achieved high dissolution for both compounds, especially when Soluplus® was used as carrier. The dissolution efficiency increased up to 18 (EZE) and 6 (LOV) times in ternary solid dispersions, compared to the crystalline drugs. ELS 1:1 75% preserved its amorphous state during 30 days, in different stability conditions.A spray dried ternary solid dispersion able to enhance the dissolution rate of two poorly soluble, therapeutically complementary drugs, is reported for the first time. These promising results open new perspectives for the development of more advanced FDCs.
Keywords: co-amorphous systems; ezetimibe; fixed dose combinations; lovastatin; ternary solid dispersions

Characterization of Supersaturated Danazol Solutions – Impact of Polymers on Solution Properties and Phase Transitions by Matthew J. Jackson; Umesh S. Kestur; Munir A. Hussain; Lynne S. Taylor (1276-1288).
Excipients are essential for solubility enhancing formulations. Hence it is important to understand how additives impact key solution properties, particularly when supersaturated solutions are generated by dissolution of the solubility enhancing formulation. Herein, the impact of different concentrations of dissolved polymers on the thermodynamic and kinetic properties of supersaturated solutions of danazol were investigated.A variety of experimental techniques was used, including nanoparticle tracking analysis, fluorescence and ultraviolet spectroscopy and flux measurements to characterize the solution phase behavior.Neither the crystalline nor amorphous solubility of danazol was impacted by common amorphous solid dispersion polymers, polyvinylpyrrolidone, hydroxypropylmethyl cellulose (HPMC) or HPMC-acetate succinate. Consequently, the maximum membrane transport rate was limited only by the amorphous solubility, and not by the presence of the polymers. The polymers were able to inhibit crystallization to some extent at concentrations as low as 1 μg/mL, with the maximum effectiveness being reached at 10 μg/mL. Aqueous danazol solutions formed a drug-rich phase with a mean size of 250 nm when the concentration exceeded the amorphous solubility, and the polymers modified the surface properties of this drug-rich phase.The phase behavior of supersaturated solutions is complex and the kinetics of phase transformations can be substantially modified by polymeric additives present at low concentrations. However, fortunately, these additives do not appear to impact the bulk thermodynamic properties of the solution, thus enabling supersaturated solutions, which provide enhanced membrane transport relative to saturated solutions to be generated.
Keywords: crystallization; liquid liquid phase separation; membrane transport; supersaturation

Lomustine Nanoparticles Enable Both Bone Marrow Sparing and High Brain Drug Levels – A Strategy for Brain Cancer Treatments by Funmilola A. Fisusi; Adeline Siew; Kar Wai Chooi; Omotunde Okubanjo; Natalie Garrett; Katerina Lalatsa; Dolores Serrano; Ian Summers; Julian Moger; Paul Stapleton; Ronit Satchi-Fainaro; Andreas G Schätzlein; Ijeoma F. Uchegbu (1289-1303).
The blood brain barrier compromises glioblastoma chemotherapy. However high blood concentrations of lipophilic, alkylating drugs result in brain uptake, but cause myelosuppression. We hypothesised that nanoparticles could achieve therapeutic brain concentrations without dose-limiting myelosuppression.Mice were dosed with either intravenous lomustine Molecular Envelope Technology (MET) nanoparticles (13 mg kg−1) or ethanolic lomustine (6.5 mg kg−1) and tissues analysed. Efficacy was assessed in an orthotopic U-87 MG glioblastoma model, following intravenous MET lomustine (daily 13 mg kg−1) or ethanolic lomustine (daily 1.2 mg kg−1 - the highest repeated dose possible). Myelosuppression and MET particle macrophage uptake were also investigated.The MET formulation resulted in modest brain targeting (brain/ bone AUC0-4h ratios for MET and ethanolic lomustine = 0.90 and 0.53 respectively and brain/ liver AUC0-4h ratios for MET and ethanolic lomustine = 0.24 and 0.15 respectively). The MET formulation significantly increased mice (U-87 MG tumours) survival times; with MET lomustine, ethanolic lomustine and untreated mean survival times of 33.2, 22.5 and 21.3 days respectively and there were no material treatment-related differences in blood and femoral cell counts. Macrophage uptake is slower for MET nanoparticles than for liposomes.Particulate drug formulations improved brain tumour therapy without major bone marrow toxicity.
Keywords: glioblastoma multiforme; lomustine; molecular envelope technology (MET); myelosuppression; nanoparticles

Erratum to: Translational Modeling in Schizophrenia: Predicting Human Dopamine D2 Receptor Occupancy by Martin Johnson; Magdalena Kozielska; Venkatesh Pilla Reddy; An Vermeulen; Hugh A. Barton; Sarah Grimwood; Rik de Greef; Geny M. M. Groothuis; Meindert Danhof; Johannes H. Proost (1305-1306).

AAPSConnection (1307-1309).