• Crystal engineering of ibuprofen using starch derivatives in crystallization medium to produce promising ibuprofen with improved pharmaceutical performance

      Nokhodchi, Ali; Homayouni, Alireza; Araya, Ruta; Kaialy, Waseem; Obeidat, Wasfy; Asare-Addo, Kofi (Royal Society of Chemistry, 2015)
      Ibuprofen exhibits poor flow, poor compaction and dissolution behaviour, and it is prone to capping after ejection from the die. Therefore, the aim of the present research was to engineer ibuprofen crystals in the presence of two disintegrants (starch and sodium starch glycolate) in order to improve its flow, compactibility and dissolution behaviour simultaneously. To this end ibuprofen and different concentrations of disintegrant (0.25 to 10% w/w in case of starch and 0.25 to 7% w/w in case of sodium starch glycolate) were dissolved in ethanol and water respectively. The ibuprofen solution was then added to the aqueous solutions containing the different concentrations of disintegrant. Ibuprofen precipitated within 10 min and the crystals were separated and dried for further studies. The obtained crystals were characterized in terms of flow, density, tablet hardness, dissolution behaviour and solid state. The results showed most of engineered ibuprofen to have better flow with a high compactibility. The results also showed that an increase in the concentration of starch in the crystallization medium resulted in a reduction in the hardness of ibuprofen tablets, but this was not the case for ibuprofen samples engineered in the presence of sodium starch glycolate. It is interesting to note that although engineered ibuprofen showed superior dissolution as compared to untreated ibuprofen, the highest concentration of starch (10%) or sodium starch glycolate (7%) slowed down the release remarkably due to an increase in the viscosity of the dissolution medium around drug particles. Solid state analysis (FT-IR, XRPD and DSC) ruled out the presence of different polymorphic forms and also any interaction between these disintegrants and ibuprofen. In conclusion, the engineering of ibuprofen in the presence of disintegrant showed how properties such as flow, compaction and dissolution behaviour can be simultaneously manipulated to suit a desired application.
    • Comparative evaluation of drug release from aged prolonged polyethylene oxide tablet matrices: effect of excipient and drug type.

      Shojaee, Saeed; Kaialy, Waseem; Cumming, Kenneth Iain; Nokhodchi, Ali (Informa healthcare, 2014-11-20)
      Abstract Polyethylene oxide (PEO) undergoes structural adjustments caused by elevated temperatures, which results in loss of its stability within direct compression tablets. The aim of this study was to evaluate the influence of filler solubility on the drug delivery process of matrix tablets containing drugs with different water-solubility properties and stored at elevated temperature. The results demonstrated that in the case of propranolol HCl (highly water-soluble) tablet matrices, soluble lactose promoted drug release, whereas, a stable release of drug was observed with insoluble DCP. A drug release pattern similar to the propranolol HCl formulation containing DCP was obtained for hydrophilic matrix tablets containing either lactose or DCP for the less water-soluble drug, zonisamide. In the case of the partially water-soluble drug, theophylline, formulated with lower molecular weight PEO 750, drug release increased considerably in the presence of both fillers with increasing storage time, however a stable release rate (similar to fresh samples) was observed in the case of higher molecular weight PEO 303 tablet matrices containing theophylline with either lactose or DCP. The hydration properties (e.g. solubility) of the diluents had a considerable effect on drug release behavior from various model matrices; this effect was dependent on both molecular weight of PEO and solubility of drug.
    • Computational predictions of glass-forming ability and crystallization tendency of drug molecules.

      Alhalaweh, Amjad; Alzghoul, Ahmad; Kaialy, Waseem; Mahlin, Denny; Bergström, Christel A S (ACS Publications, 2014-09-02)
      Amorphization is an attractive formulation technique for drugs suffering from poor aqueous solubility as a result of their high lattice energy. Computational models that can predict the material properties associated with amorphization, such as glass-forming ability (GFA) and crystallization behavior in the dry state, would be a time-saving, cost-effective, and material-sparing approach compared to traditional experimental procedures. This article presents predictive models of these properties developed using support vector machine (SVM) algorithm. The GFA and crystallization tendency were investigated by melt-quenching 131 drug molecules in situ using differential scanning calorimetry. The SVM algorithm was used to develop computational models based on calculated molecular descriptors. The analyses confirmed the previously suggested cutoff molecular weight (MW) of 300 for glass-formers, and also clarified the extent to which MW can be used to predict the GFA of compounds with MW < 300. The topological equivalent of Grav3_3D, which is related to molecular size and shape, was a better descriptor than MW for GFA; it was able to accurately predict 86% of the data set regardless of MW. The potential for crystallization was predicted using molecular descriptors reflecting Hückel pi atomic charges and the number of hydrogen bond acceptors. The models developed could be used in the early drug development stage to indicate whether amorphization would be a suitable formulation strategy for improving the dissolution and/or apparent solubility of poorly soluble compounds.
    • Experimental and Numerical Investigation of the Effect of Pellet Size on the Adsorption Characteristics of Activated Carbon/Ethanol

      Elsayed, A.; Mahmoud, S.; Al-Dadah, R.; Bowen, J.; Kaialy, Waseem (2014)
      Low temperature adsorption cooling is an attractive heat powered cooling technology suitable for various applications where waste heat is available. The use of activated carbon as adsorbent with ethanol offers potential for low temperature cooling applications like the food retail industry. Activated carbons are commercially available in the form of powders, granules and pellets. Although powder materials have the advantage of good adsorption kinetics but they are difficult to integrate in adsorption beds. Pellets and granules come at various shapes and sizes and can be effectively accommodated in adsorption beds but offer slower kinetics compared to the powder form. This work experimentally and numerically investigates the effect of pellet size on the ethanol adsorption characteristics of Norit RX3 activated carbon. Dynamic vapour sorption (DVS) testing was used for measuring the adsorption isotherms and kinetics for a range of pellet lengths ranging from 3mm to 12mm. COMSOL Multiphysics was used to simulate the adsorption effect taking into account the diffusion process. Results showed that increasing the pellet dimension in terms of diameter and length reduces the adsorption kinetics.
    • The influence of vitamin E succinate on the stability of polyethylene oxide PEO controlled release matrix tablets.

      Shojaee, Saeed; Cumming, Iain; Kaialy, Waseem; Nokhodchi, Ali (Elsevier, 2013-11-01)
      Hydrophilic matrices are a principal technology used for extended release (ER) oral dosage forms and a recent review concluded that their development is currently one of the most important challenges in pharmaceutical research. High molecular weight polyethylene oxides (PEOs) have been proposed as an alternative to hydroxypropylmethylcellulose (HPMC) for the manufacture of controlled release matrix tablets. It is known that PEO's are prone to oxidative degradation which can occur by chain scission and can be catalyzed by metal ions. In this study, we investigated the stability of PEO matrix tablets, of different molecular weight, containing diltiazem hydrochloride, when stored at 40 °C. The results show that there were dramatic increases in the release rate of the diltiazem following storage over only a few weeks, resulting in immediate release profiles after eight weeks, even for the highest molecular weight grade. We employed Gel permeation chromatography (GPC), viscosity and differential scanning calorimetry (DSC) techniques to try and determine the underlying causes of these dramatic shifts in dissolution profiles on storage. The results showed that there were significant decreases in the molecular weight of the PEO's during storage. The second part of the study looked at the addition of three different levels of vitamin E succinate to the tablets. The results clearly demonstrate the ability of the added antioxidant to reverse the significant reductions in molecular weight seen using GPC, viscosity and DSC. Importantly the addition of the antioxidant was able to stabilize the release profile of the diltiazem especially when present at a 1% level. Researchers and those working in pharmaceutical development should be aware of the potential stability risks when making matrix tablets containing PEO's and may wish to consider the addition of an antioxidant to the tablet formulation.
    • Engineered mannitol ternary additives improve dispersion of lactose-salbutamol sulphate dry powder inhalations.

      Kaialy, Waseem; Nokhodchi, Ali (Springer, 2013-07)
      The aim of this study was to evaluate the influence of novel engineered fine mannitol particles (4.7%, w/w) on the performance of lactose-salbutamol sulphate dry powder inhaler (DPI) formulations to obtain promising aerosolisation properties. The results showed that the more elongated the fine mannitol particles, the weaker the drug-carrier adhesion, the better the drug content homogeneity, the higher the amount of drug expected to be delivered to the lower airways and the higher the total DPI formulation desirability. Linear relationships were established showing that mannitol particles with a more elongated shape generated powders with broader size distributions and that were less uniform in shape. The weaker the drug-carrier adhesion, the higher the fine particle fraction of the drug is upon aerosolisation. It is believed that more elongated fine mannitol particles reduce the number of drug-carrier and drug-drug physical contact points and increase the ability of the drug particles to travel into the lower airways. Additionally, a lower drug-carrier contact area, lower drug-carrier press-on forces and easier drug-carrier detachment are suggested in the case of formulations containing more elongated fine mannitol particles. Ternary 'drug-coarse carrier-elongated fine ternary component' DPI formulations were more favourable than both 'drug-coarse carrier' and 'drug-elongated coarse carrier' binary formulations. This study provides a comprehensive approach for formulators to overcome the undesirable properties of dry powder inhalers, as both improved aerosolisation performance and reasonable flow characteristics were obtained using only a small amount of elongated engineered fine mannitol particles.
    • Treating mannitol in a saturated solution of mannitol: a novel approach to modify mannitol crystals for improved drug delivery to the lungs.

      Kaialy, Waseem; Nokhodchi, Ali (Elsevier, 2013-05-01)
      The aim of this study was to evaluate the influence of treatment of a promising dry powder aerosol carrier (mannitol) on the aerosolization performance of salbutamol sulphate (SS) using a novel approach: treating excess commercial carrier particles in a saturated solution of the same carrier. Commercial mannitol (CM) particles were treated with aqueous mannitol supersaturated solutions (20% and 25% w/v), under stirring, (300 rpm) for either 24h or 48 h. The results showed that particle treatment did not alter the polymorphic form of mannitol (β-mannitol); however, all treated mannitol particles demonstrated smoother surface topography and improved aerosolization performance compared to CM in dry powder inhalations. Unlike the concentration of mannitol solution used during treatment, the time of treatment to collect mannitol crystals was an essential key to modify the physical properties of mannitol and its effect on the aerosolization performance. In comparison to mannitol particles treated for 48 h, mannitol particles treated for 24h demonstrated larger size, more elongated-less regular shape, and smoother surfaces. No apparent relationship was obtained between in vitro aerosolisation behavior of SS with either mannitol particle size or shape descriptors. However, despite their larger size and more irregular-less uniformed shape, treated mannitol particles with smoother surfaces generated drug particles with smaller aerodynamic size and are expected to deliver higher amounts of drug to lower airways. The results demonstrated the potential of treating mannitol particles in aqueous solutions of the same material under controlled conditions to produce mannitol particles promising for dry powder inhaler systems. The results suggested that mannitol particle surface texture properties dominate over both particle size and particle shape of mannitol in terms of determining the aerosolization performance of mannitol.
    • The influence of agitation sequence and ionic strength on in vitro drug release from hypromellose (E4M and K4M) ER matrices--the use of the USP III apparatus.

      Asare-Addo, Kofi; Kaialy, Waseem; Levina, Marina; Rajabi-Siahboomi, Ali; Ghori, Mohammed U; Supuk, Enes; Laity, Peter R; Conway, Barbara R; Nokhodchi, Ali (Elsevier, 2013-04-01)
      Theophylline extended release (ER) matrices containing hypromellose (hydroxypropyl methylcellulose (HPMC) E4M and K4M were evaluated in media with a pH range of 1.2-7.5, using an automated USP type III, Bio-Dis dissolution apparatus. The objectives of this study were to evaluate the effects of systematic agitation, ionic strength and pH on the release of theophylline from the gel forming hydrophilic polymeric matrices with different methoxyl substitution levels. Tribo-electric charging of hypromellose, theophylline and their formulated blends containing E4M and K4M grades has been characterised, along with quantitative observations of flow, compression behaviour and particle morphology. Agitations were studied at 5, 10, 15, 20, 25, 30 dips per minute (dpm) and also in the ascending and descending order in the dissolution vials. The ionic concentration strength of the media was also varied over a range of 0-0.4M to simulate the gastrointestinal fed and fasted states and various physiological pH conditions. To study the effect of ionic strength on the hydrophilic matrices, agitation was set at 20 dpm. The charge results on individual components imply that the positively charged particles have coupled with the negatively charged particles to form a stable ordered mixture which is believed to result in a more homogeneous and stable system. The particle shape analysis showed the HPMC K4M polymer to have a more irregular morphology and a rougher surface texture in comparison to the HPMC E4M polymer, possibly a contributory factor to the gelation process. The results showed gelation occurred quicker for the K4M tablet matrices. Drug release increased with increased agitation. This was more pronounced for the E4M tablet matrices. The ionic strength also had more of an effect on the drug release from the E4M matrices. The experiments highlighted the resilience of the K4M matrices in comparison with the E4M matrices. The results thus show that despite similar viscosities of E4M and K4M, the methoxyl substitution makes a difference to their control of drug release and as such care and consideration should be given to the choice of polymer used for extended release. The use of systematic change of agitation method and ionic strength may indicate potential fed and fasted effects on drug release from hydrophilic matrices.
    • A novel sensing technique for measurement of magnitude and polarity of electrostatic charge distribution across individual particles.

      Hussain, Tariq; Kaialy, Waseem; Deng, Tong; Bradley, Mike S A; Nokhodchi, Ali; Armour-Chélu, David (Elsevier, 2013-01-30)
      Electrostatic charge is generated during powder handling due to particle-particle and particle-wall collisions, rubbing, sliding, and rolling. In case of bipolar charge generation, the electrostatic forces may significantly change the inner forces and increase powder adhesion and cause a serious problem in material handling process. Therefore, the knowledge of distribution of charge across the individual particles is helpful to identify the role of triboelectrification and the effects of various relevant variables especially change in the contact materials, environmental conditions during processing, etc. A novel approach based on inductive sensor has been developed to detect the either polarity of charged particle and to characterise the bipolar charge distribution in the population of particulate material. To achieve this, an amplification unit configured as a pure integrator and signal processing techniques has been used to de-noise and correct the baseline of signal and MATLAB algorithm developed for peak detection. The polarity of charged particles obtained by this method is calibrated with Faraday pail method and the results are promising. Experimental study has been carried out by using two distinct populations of oppositely charged particles (glass beads-PVC, olivine sand, and silica sand). The obtained results indicate that the method is able to detect the distribution of polarities of charged particles.
    • Antisolvent crystallisation is a potential technique to prepare engineered lactose with promising aerosolisation properties: effect of saturation degree.

      Kaialy, Waseem; Nokhodchi, Ali (Elsevier, 2012-11-01)
      Engineered lactose particles were prepared by anti-solvent crystallisation technique using lactose solutions with different saturation degrees. In comparison to commercial lactose, engineered lactose particles exhibited less elongated and more irregular shape (large aggregates composed of smaller sub-units), rougher surface texture, higher specific surface area, and different anomer form. Engineered lactose powders demonstrated smaller bulk density, smaller tap density, and higher porosity than commercial lactose powder. Dry powder inhaler (DPI) formulations containing engineered lactose and salbutamol sulphate as a model drug demonstrated improved drug content homogeneity and higher amounts of drug delivered to lower airway regions. Higher fine particle fraction of drug was obtained in the case of lactose powders with higher porosity, higher specific surface area and higher fine particle content (<5 μm). The results indicated that the higher the saturation degree of lactose solution used during crystallisation the smaller the specific surface area, the higher the amorphous lactose content, and the higher the β-lactose content of engineered lactose particles. Also, lactose powders obtained from lactose solution with higher degree of saturation showed higher bulk and tap densities and smaller porosity. Engineered lactose powders crystallized from lower saturation degree (20% and 30% w/v) deposited higher amounts of drug on lower airway regions. In conclusion, this study demonstrated that it is possible to prepare engineered lactose particles with favourable properties (e.g. higher fine particle fraction and better drug content homogeneity) for DPI formulations by using lactose solutions with lower degree of saturation during crystallisation process.
    • Influence of lactose carrier particle size on the aerosol performance of budesonide from a dry powder inhaler

      Kaialy, Waseem; Alhalaweh, Amjad; Velaga, Sitaram P.; Nokhodchi, Ali (Elsevier, 2012-09)
      The purpose of this study was to evaluate the effect of carrier particle size on properties of dry powder and its effect on dry powder inhaler (DPI) performance. Commercial α-lactose-monohydrate, a commonly used carrier in DPI formulations, was carefully sieved to obtain different lactose size fractions, namely Lac A (90–125 μm), Lac B (63–90 μm), Lac C (45–63 μm), Lac D (20–45 μm), and Lac E (< 20 μm). The lactose samples were analysed in terms of size, shape, solid state, density, and flowability. Lactose particles were blended with budesonide (< 5 μm) powder to generate five different formulations. These formulations were then evaluated in terms of budesonide–lactose adhesion properties, drug content homogeneity, and in vitro aerosolisation performance. The results demonstrated that lactose samples with smaller particle volume mean diameter have higher amorphous lactose content, higher true density (linear, r2 = 0.9932), higher surface smoothness (linear, r2 = 0.8752), smaller angularity (linear, r2 = 0.921), smaller bulk density, higher porosity (linear, r2 = 0.914), poorer flowability, and higher specific surface area. In general, the smaller the lactose particles the smaller are the budesonide–lactose adhesion properties. Budesonide formulated with smaller lactose particles exhibited smaller aerodynamic diameter and higher amounts of budesonide were delivered to lower stages of the impactor indicating improved DPI aerosolisation performance. However, the use of lactose particles with smaller volume mean diameter had a detrimental effect on budesonide content homogeneity and caused an increase in the amounts of budesonide deposited on oropharyngeal region. Therefore, particle size of the lactose within dry powder inhaler formulations should be selected carefully. Accordingly, higher drug aerosolisation efficiency of lactose particles with smaller size may have to be balanced due to considerations of other disadvantages including poorer flowability, reduced formulation stability, higher potential side effects, and higher dose variability.
    • Dry powder inhalers: mechanistic evaluation of lactose formulations containing salbutamol sulphate.

      Kaialy, Waseem; Ticehurst, Martyn; Nokhodchi, Ali (Elsevier, 2012-02-28)
      The purpose of this study was to evaluate the relationships between physicochemical properties and aerosolisation performance of different grades of lactose. In order to get a wide range of physicochemical properties, various grades of lactose namely Flowlac 100 (FLO), Lactopress anhydrous 250 (LAC), Cellactose 80 (CEL), Tablettose 80 (TAB), and Granulac 200 (GRA) were used. The different lactose grades were carefully sieved to separate 63-90 μm particle size fractions and then characterised in terms of size, shape, density, flowability, and solid state. Formulations were prepared by blending each lactose with salbutamol sulphate (SS) at ratio of 67.5:1 (w/w), and then evaluated in terms of SS content uniformity, lactose-SS adhesion properties, and in vitro aerosolisation performance delivered from the Aerolizer. Sieved lactose grades showed similar particle size distributions (PSDs) and good flow properties but different particle shape, particle surface texture, and particle solid state. Content uniformity assessments indicated that lactose particles with rougher surface produced improved SS homogeneity within DPI formulation powders. Lactose-SS adhesion assessments indicated that lactose particles with more elongated shape and the rougher surface showed smaller adhesion force between lactose and salbutamol sulphate. Lactose powders with higher bulk density and higher tap density produced smaller emission (EM) and higher drug loss (DL) of SS. In vitro aerosolisation for various lactose grades followed the following rank order in terms of deposition performance: GRA>TAB>LAC ≈ CEL>FLO. Linear relationships were established showing that in order to maximize SS delivery to lower airway regions, lactose particles with more elongated shape, more irregular shape, and rougher surface are preferred. Therefore, considerable improvement in DPI performance can be achieved by careful selection of grade of lactose included within DPI formulations.
    • The influence of physical properties and morphology of crystallised lactose on delivery of salbutamol sulphate from dry powder inhalers.

      Kaialy, Waseem; Martin, Gary P; Larhrib, Hassan; Ticehurst, Martyn D; Kolosionek, Ewa; Nokhodchi, Ali (Elsevier, 2012-01-01)
      The aim of this work was to investigate the mechanistic evaluation of physicochemical properties of new engineered lactose on aerosolisation performance of salbutamol sulphate (SS) delivered from dry powder inhaler (DPI). Different crystallised lactose particles were obtained from binary mixtures of butanol:acetone. The sieved fractions (63-90 μm) of crystallised lactose were characterised in terms of size, shape, flowability, true density and aerosolisation performance (using multiple twin stage impinger (MSLI), Aerolizer(®) inhaler device, and salbutamol sulphate as a model drug). Compared to commercial lactose, crystallised lactose particles were less elongated, covered with fine lactose particles, and had a rougher surface morphology. The crystallised lactose powders had a considerably lower bulk and tap density and poorer flow when compared to commercial lactose. Engineered carrier with better flow showed improved drug content homogeneity, reduced amounts of drug "deposited" on the inhaler device and throat, and a smaller drug aerodynamic diameter upon inhalation. Aerodynamic diameter of salbutamol sulphate increased as lactose aerodynamic diameter decreased (linear, R(2)=0.9191) and/or as fine particle lactose content increased (linear, R(2)=0.8653). Improved drug aerosolisation performance in the case of crystallised lactose particles was attributed to lower drug-carrier adhesion forces due to a rougher surface and higher fine particle content. In conclusion, this work proved that using binary combinations of solvents in crystallisation medium is vital in modification of the physicochemical and micromeritic properties of carriers to achieve a desirable aerosolisation performance from DPI formulations. Among all lactose samples, lactose particles crystallised from pure butanol generated the highest overall DPI formulations desirability.
    • Effect of carrier particle shape on dry powder inhaler performance.

      Kaialy, Waseem; Alhalaweh, Amjad; Velaga, Sitaram P; Nokhodchi, Ali (Elsevier, 2011-12-12)
      The aim of this study was to characterise the aerosolisation properties of salbutamol sulphate (SS) from dry powder inhaler (DPI) formulations containing different carrier products. The difference in the elongation ratio (ER) of the different carriers was highlighted. Different set of carriers, namely commercial mannitol (CM), commercial lactose (CL), cooling crystallised mannitol (CCM), acetone crystallised mannitol (ACM) and ethanol crystallised mannitol (ECM) were used and inspected in terms of size, shape, density, crystal form, flowability, and in vitro aerosolisation performance using Multi Stage Liquid Impinger (MSLI) and Aerolizer inhaler device. Solid-state and morphological characterization showed that CM product was in pure β-form having particles with smaller ER (CM: ER=1.62 ± 0.04) whereas ACM and ECM mannitol particles were in pure α form with higher ER (ACM: ER=4.83 ± 0.18, ECM: ER=5.89 ± 0.19). CCM product crystallised as mixtures of β-form and δ-form and showed the largest variability in terms of particle shape, size, and DPI performance. Linear relationships were established showing that carrier products with higher ER have smaller bulk density (D(b)), smaller tap density (D(t)), higher porosity (P), and poorer flow properties. In vitro aerosolisation assessments showed that the higher the ER of the carrier particles the greater the amounts of SS delivered to lower airway regions indicating enhanced DPI performance. Yet, DPI performance enhancement by increasing carrier ER reached a "limit" as increasing carrier ER from 4.83±0.18 (ACM) to 5.89±0.19 (ECM) did not significantly alter fine particle fraction (FPF) of SS. Also, carrier particles with higher ER were disadvantageous in terms of higher amounts of SS remained in inhaler device (drug loss) and deposited on throat. Linear relationship was established (r(2)=0.87) showing that the higher the carrier ER the lower the drug emission (EM) upon inhalation. Moreover, poorer flowability for carrier products with higher ER is disadvantageous in terms of DPI formulation dose metering and processing on handling scale. In conclusion, despite that using carrier particles with higher ER can considerably increase the amounts of drug delivered to lower airway regions; this enhancement is restricted to certain point. Also, other limitations should be taken into account including higher drug loss and poorer flowability.
    • Non-Steroidal Anti-Inflammatory Drugs, DNA Repair and Cancer

      Dibra, Harpreet K.; Perry, Chris J.; Nicholl, Iain D. (InTech, 2011)
    • The enhanced aerosol performance of salbutamol from dry powders containing engineered mannitol as excipient.

      Kaialy, Waseem; Martin, Gary P; Ticehurst, Martyn D; Momin, Mohammed N; Nokhodchi, Ali (el, 2010-06-15)
      The aim of the present study was to investigate the effect of crystallising mannitol from different binary mixtures of acetone/water on the resultant physical properties and to determine the effects of any changes on in vitro aerosolisation performance, when the different mannitol crystals were used as a carrier in dry powder inhaler formulations containing salbutamol sulphate. Mannitol particles were crystallised under controlled conditions by dissolving the sugar in water and precipitating the sugar using binary mixtures of acetone/water in different percentages as anti-solvent media. For comparison purposes the physical properties and deposition behaviour of commercially available mannitol were also studied. SEM showed that all crystallised mannitol particles were more elongated than the commercial mannitol. Solid state studies revealed that commercial mannitol and mannitol crystallised using acetone in the presence of 10-25% v/v water as anti-solvent was beta-polymorphic form whereas mannitol crystallised in the presence of a small amount of water (0-7.5%) was the alpha-form. All the crystallised mannitol samples showed poor flowability. Nevertheless, the powdered crystallised mannitol and commercial samples were blended with salbutamol in the ratio 67.5:1. The aerosolisation performance of the formulations containing the engineered mannitol (evaluated using Multi Stage Liquid Impinger) was considerably better than that of the commercial mannitol formulation (the fine particle fraction was increased from 15.42% to 33.07-43.99%, for the formulations containing crystallised mannitol). Generally, carriers having a high tapped density and high fraction of fine carrier particles produced a high FPF. The improvement in the DPI performance could be attributed to the presence of elongated carrier particles with smooth surfaces since these are believed to have less adhesive forces between carrier and the drug resulting in easier detachment of the drug during the inhalation.
    • Pseudoislets as primary islet replacements for research: Report on a symposium at King's College London, London UK

      Persaud, Shanta; Arden, Catherine; Bergsten, P.; Bone, Adrian J.; Brown, James; Dunmore, Simon J; Harrison, Moira; Hauge-Evans, Astrid; Kelly, Catriona; King, Aileen; et al. (Landes Bioscience, 2010)
      Laboratory-based research aimed at understanding processes regulating insulin secretion and mechanisms underlying β-cell dysfunction and loss in diabetes often makes use of rodents, as these processes are in many respects similar between rats/mice and humans. Indeed, a rough calculation suggests that islets have been isolated from as many as 150,000 rodents to generate the data contained within papers published in 2009 and the first four months of 2010. Rodent use for islet isolation has been mitigated, to a certain extent, by the availability of a variety of insulin-secreting cell lines that are used by researchers world-wide. However, when maintained as monolayers the cell lines do not replicate the robust, sustained secretory responses of primary islets which limits their usefulness as islet surrogates. On the other hand, there have been several reports that configuration of MIN6 β-cells, derived from a mouse insulinoma, as three-dimensional cell clusters termed ‘pseudoislets’ largely recapitulates the function of primary islet β-cells. The Diabetes Research Group at King’s College London has been using the MIN6 pseudoislet model for over a decade and they hosted a symposium on “Pseudoislets as primary islet replacements for research”, which was funded by the UK National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs), in London on 15th and 16th April 2010. This small, focused meeting was conceived as an opportunity to consolidate information on experiences of working with pseudoislets between different UK labs, and to introduce the theory and practice of pseudoislet culture to laboratories working with islets and/or β-cell lines but who do not currently use pseudoislets. This short review summarizes the background to the development of the cell line-derived pseudoislet model, the key messages arising from the symposium and emerging themes for future pseudoislet research
    • Individualised assessment of response to clopidogrel in patients presenting with acute coronary syndromes: a role for short thrombelastography?

      Cotton, James M.; Worrall, A. M.; Hobson, A. R.; Smallwood, A.; Amoah, V.; Dunmore, Simon J.; Nevill, Alan M.; Raghuraman, R. P.; Vickers, J.; Curzen, N. (2010)
      INTRODUCTION: There is considerable interindividual variation in response to the antiplatelet agent clopidogrel. Hyporesponse predicts negative outcomes in patients presenting with a variety of ischemic cardiac conditions and following intracoronary stent placement. Many tests of clopidogrel activity are time consuming and complex. Short thromboelastography (s-TEG) allows rapid measurement of platelet clopidogrel response. AIMS: We initiated this study to investigate the utility of s-TEG in assessing the response to clopidogrel in patients presenting with acute coronary syndromes (ACS) and to compare these results with established clopidogrel monitoring techniques. METHODS: Patients admitted with unstable angina (UA) or Non ST elevation myocardial infarction (NSTEMI) undergoing coronary angiography were recruited. After routine loading with clopidogrel, all patients were tested with s-TEG and Accumetrics Verify-Now rapid platelet function analyzer (VN-RPFA). We used the modified TEG technique of measuring area under the curve at 15 min (AUC15), which allows a rapid estimation of antiplatelet response. Vasodilator-stimulated phosphoprotein phosphorylation (VASP) was also tested in a subgroup of patients. Clinical follow-up was obtained at 1 year. s-TEG results were correlated with VN-RPFA and VASP findings. RESULTS: A total of 49 patients (33 male, mean age 63) were recruited and tested with s-TEG and VN-RPFA and a total of 39 patients were also assessed with VASP. s-TEG readings correlated well with VN-RPFA (r(2)= 0.54, P < 0.0001) and VASP (r(2)= 0.26, P= 0.001). CONCLUSION: s-TEG provides timely results which compare to current tests of clopidogrel activity. This technique can also be used to measure a variety of other clotting parameters and as such could develop into a valuable near patient test for the interventional cardiologist.
    • Visfatin regulates insulin secretion, insulin receptor signalling and mRNA expression of diabetes-related genes in mouse pancreatic beta-cells.

      Brown, James E. P.; Onyango, David J.; Ramanjaneya, Manjunath; Conner, Alex C.; Patel, Snehal T.; Dunmore, Simon J.; Randeva, Harpal S. (Society for Endocinology, 2010)
      The role of the adipocyte-derived factor visfatin in metabolism remains controversial, although some pancreatic beta-cell-specific effects have been reported. This study investigated the effects of visfatin upon insulin secretion, insulin receptor activation and mRNA expression of key diabetes-related genes in clonal mouse pancreatic beta-cells. beta-TC6 cells were cultured in RPMI 1640 and were subsequently treated with recombinant visfatin. One-hour static insulin secretion was measured by ELISA. Phospho-specific ELISA and western blotting were used to detect insulin receptor activation. Real-time SYBR Green PCR array technology was used to measure the expression of 84 diabetes-related genes in both treatment and control cells. Incubation with visfatin caused significant changes in the mRNA expression of several key diabetes-related genes, including marked up-regulation of insulin (9-fold increase), hepatocyte nuclear factor (HNF)1beta (32-fold increase), HNF4alpha (16-fold increase) and nuclear factor kappaB (40-fold increase). Significant down-regulation was seen in angiotensin-converting enzyme (-3.73-fold) and UCP2 (-1.3-fold). Visfatin also caused a significant 46% increase in insulin secretion compared to control (P<0.003) at low glucose, and this increase was blocked by co-incubation with the specific nicotinamide phosphoribosyltransferase inhibitor FK866. Both visfatin and nicotinamide mononucleotide induced activation of both insulin receptor and extracellular signal-regulated kinase (ERK)1/2, with visfatin-induced insulin receptor/ERK1/2 activation being inhibited by FK866. We conclude that visfatin can significantly regulate insulin secretion, insulin receptor phosphorylation and intracellular signalling and the expression of a number of beta-cell function-associated genes in mouse beta-cells.
    • Regulation of beta-cell viability and gene expression by distinct agonist fragments of adiponectin

      Brown, James E. P.; Conner, Alex C..; Digby, Janet E.; Ward, Kenya L.; Ramanjaneya, Manjunath; Randeva, Harpal S.; Dunmore, Simon J. (2010)
      Obesity is an established risk factor for type 2 diabetes. Activation of the adiponectin receptors has a clear role in improving insulin resistance although conflicting evidence exists for its effects on pancreatic beta-cells. Previous reports have identified both adiponectin receptors (ADR-1 and ADR-2) in the betacell. Recent evidence has suggested that two distinct regions of the adiponectin molecule, the globular domain and a small N-terminal region, have agonist properties. This study investigates the effects of two agonist regions of adiponectin on insulin secretion, gene expression, cell viability and cell signalling in the rat beta-cell line BRIN-BD11, as well as investigating the expression levels of adiponectin receptors (ADRs) in these cells. Cells were treated with globular adiponectin and adiponectin (15-36)±leptin to investigate cell viability, expression of key beta-cell genes and ERK1/2 activation. Both globular adiponectin and adiponectin (15-36) caused significant ERK1/2 dependent increases in cell viability. Leptin co-incubation attenuated adiponectin (15-36) but not globular adiponectin induced cell viability. Globular adiponectin, but not adiponectin (15-36), caused a significant 450% increase in PDX-1 expression and a 45% decrease in LPL expression. ADR-1 was expressed at a higher level than ADR-2, and ADR mRNA levels were differentially regulated by non-esterified fatty acids and peroxisome-proliferator-activated receptor agonists. These data provide evidence of roles for two distinct adiponectin agonist domains in the beta-cell and confirm the potentially important role of adiponectin receptor agonism in maintaining beta-cell mass.