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  • 1. Bergstrom, P. O.
    et al.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Kloo, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Sebhatu, T.
    Crystal structure and physical properties of two polymorphs of ropivacaine HCl2006In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 95, no 3, 680-688 p.Article in journal (Refereed)
    Abstract [en]

    The crystal structure of two polymorphs of ropivacaine HCl have been determined, as well as their relative stability up to 100 degrees C. A geometric restriction for a solid-state transition between the two polymorphs has been identified. The packing density along the H-bonded chains form the basis for a model explaining the kinetic crystallization of the metastable form. The difference in stability and physicochemical properties between the two polymorphs can be attributed to the difference in crystal structure.

  • 2. Boissier, Catherine
    et al.
    Feidt, Francois
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Nordstierna, Lars
    Study of Pharmaceutical Coatings by Means of NMR Cryoporometry and SEM Image Analysis2012In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 101, no 7, 2512-2522 p.Article in journal (Refereed)
    Abstract [en]

    Nuclear magnetic resonance (NMR) cryoporometry and scanning electron microscopy (SEM) image analysis have been used to investigate the size and shape distribution of pores in pharmaceutical coatings. The coatings were made from a mixture of hydroxypropylcellulose (HPC) and ethylcellulose (EC). Upon solvent evaporation from a solution consisting of both the polymers, a solid polymer film is formed, which after removal of the water-soluble HPC consists of a skeleton of EC. A change in the amount of HPC enables modification of the water permeability through the films. By means of NMR cryoporometry, the presence of small pores (radius below 400 nm) was revealed with no significant change in the pore size distribution (PSD) as the HPC content in the films were changed. NMR cryoporometry showed the presence of channels of a characteristic 30-nm length scale in the films that contained more than 22% HPC. Below this threshold, the lack of interconnecting channels seems to prevent complete HPC dissolution and thereby the water permeability. SEM image analysis showed pore sizes that ranged from hundreds of nanometers up to few micrometers. Above the 22% threshold, further increase of HPC in the films resulted in an increased pore volume and wider PSD.

  • 3.
    Green, Henrik
    et al.
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Khan, Muhammad Suleman
    Jakobsen-Falk, Ingrid
    Avall-Lundqvist, Elisabeth
    Peterson, Curt
    Impact of CYP3A5(*)3 and CYP2C8-HapC on Paclitaxel/Carboplatin-Induced Myelosuppression in Patients with Ovarian Cancer2011In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 100, no 10, 4205-4209 p.Article in journal (Refereed)
    Abstract [en]

    The influence of genetic variants on paclitaxel-induced toxicity is of considerable interest for reducing adverse drug reactions. Recently, the genetic variants CYP2C8(*)3, CYP2C8-HapC, and CYP3A5(*)3 were associated with paclitaxel-induced neurotoxicity. We, therefore, investigated the impact of CYP2C8-HapC and CYP3A5(*)3 on paclitaxel/carboplatin-induced myelosuppression and neurotoxicity. Thirty-three patients from a prospective pharmacokinetics study were genotyped using pyrosequencing. Patients with variant alleles of CYP2C8-HapC were found to have significantly lower nadir values of both leukocytes and neutrophils (p < 0.05) than patients with the wild-type genotype. CYP3A5(*)3/(*)1 patients were shown to have borderline, significantly lower nadir values of leukocytes (p = 0.07) than (*)3/(*)3 patients. Combining the two genotypes resulted in a significant correlation with both leukopenia and neutropenia (p = 0.01). No effect of these genetic variants on neurotoxicity could be shown in this rather small study, but their importance for paclitaxel-induced toxicity could be confirmed.

  • 4.
    Hedenmalm, Håkan
    et al.
    KTH, Superseded Departments, Mathematics.
    Ehrsson, H.
    Andersson, A.
    Elfsson, B.
    Determination of the acid dissociation constant for cis-diamineaquachloroplatinum(II)-ion. A hydrolysis product of cisplatin1994In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 83, 859-862 p.Article in journal (Refereed)
  • 5.
    Liu, Jin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Svärd, Michael
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. University of Limerick, Ireland.
    Hippen, Perschia
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. University of Limerick, Ireland.
    Solubility and Crystal Nucleation in Organic Solvents of Two Polymorphs of Curcumin2015In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 104, no 7, 2183-9 p.Article in journal (Refereed)
    Abstract [en]

    Two crystal polymorphs of 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (curcumin) have been obtained by crystallization from ethanol (EtOH) solution. The polymorphs have been characterized by differential scanning calorimetry, infrared spectroscopy, and X-ray powder diffraction and shown to be the previously described forms I and III. The solubility of both polymorphs in EtOH and of one polymorph in ethyl acetate (EA) has been measured between 10°C and 50°C with a gravimetric method. Primary nucleation of curcumin from EtOH solution has been investigated in 520 constant temperature crystallization experiments in sealed, magnetically stirred vials under different conditions of supersaturation, temperature, and agitation rate. By a thermodynamic analysis of the melting data and solubility of form I, the solid-state activity is estimated from 10°C up to the melting point. The solubility is lower in EtOH than in EA, and in both solvents, a positive deviation from Raoult's law is observed. Form I has lower solubility than form III and is accordingly thermodynamically more stable over the investigated temperature interval. Extrapolation of solubility regression models indicates that there should be a low-temperature enantiotropic transition point, below which form I will be metastable. By slurry conversion experiments, it is established that this temperature is below -30°C. All nucleation experiments resulted in the stable form I. The induction time is observed to decrease with increasing agitation rate up to a certain point, and then increase with further increasing agitation rate; a trend previously observed for other compounds. By correlating the induction time data obtained at different supersaturation and temperature, the interfacial energy of form I in EtOH is estimated to be 3.0 mJ/m(2) . 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:2183-2189, 2015.

  • 6.
    Nordström, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Phase Equilibria and Thermodynamics of p-Hydroxybenzoic acid2006In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 95, no 4, 748-760 p.Article in journal (Refereed)
    Abstract [en]

    The prevalence of phases and associated solubilities of p-hydroxybenzoic acid have been investigated in methanol, acetonitrile, acetic acid, acetone, water, and ethyl acetate at temperatures from 10 to 50 degrees C. Thermodynamic data was acquired through determination of van't Hoff enthalpy of solution, enthalpy of fusion, and melting temperature. Indications of polymorphic enantiotropy were found primarily through solubility analysis and FTIR-ATR. A comprehensive thermodynamic investigation disclosed correlation between the van't Hoff enthalpy of solution and the solubility in different solvents. A higher solubility is linked to a lower van't Hoff enthalpy of solution. A thermodynamic analysis to discriminate between different solid phases is presented.

  • 7.
    Nordström, Fredrik
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Rasmuson, Åke C.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Sheikh, A. Y.
    Analysis of solution nonideality of a pseudomorphic drug system through a comprehensive thermodynamic framework for the design of a crystallization process2004In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 93, no 4, 995-1004 p.Article in journal (Refereed)
    Abstract [en]

    Solutions of a semipolar drug belonging to the alpha(v) beta(iii) integrin antagonist class of compounds were studied in a comprehensive thermodynamic framework. The solubility of two pseudomorphic forms (an anhydrate and a monohydrate) was measured at several temperatures and various solvent mixtures of acetonitrile and water. Both forms displayed a bell-shaped solubility behavior as a function of cosolvent composition. Thermodynamic framework used to analyze the data comprised van't Hoff and enthalpy-entropy compensation analyses. The two pseudomorphs exhibited linear temperature dependence from 25 to 65degreesC at all solvent compositions (i.e., ideal behavior with temperature for fixed solvent composition). Plots of enthalpy of solublization and Gibbs free energy showed two distinct regions with contrasting thermodynamic, and consequently, underlying structural properties (indicating non-deal behavior with solvent composition for a fixed temperature). Solubility increased due to entropy effects in the acetonitrile rich region, whereas enthalpy effects dominated solublization in the water-rich region. Quantification of this phenomenon by plotting DeltaH versus DeltaG showed considerable nonlinearity, and that the two regions were separated by a significant discontinuity-a trend rarely seen before in the literature. The reason behind this behavior is believed to be due to the complex interactions in the solution of the drug in water acetonitrile solvent system. A very significant aspect of the comprehensive thermodynamic analysis is that it helped explain the puzzling feature of the data, which showed that the free energy of phase transformation between the two pseudomorphic forms for a given temperature was not independent of the solvent composition. The resulting explanation has major consequences for crystallization process development.

  • 8.
    Svärd, Michael
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Gracin, Sandra
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Oiling out or molten hydrate-liquid-liquid phase separation in the system vanillin-water2007In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 96, no 9, 2390-2398 p.Article in journal (Refereed)
    Abstract [en]

    Vanillin crystals in a saturated aqueous solution disappear and a second liquid phase emerges when the temperature is raised above 51 degrees C. The phenomenon has been investigated with crystallization and equilibration experiments, using DSC, TGA, XRD and hot-stage microscopy for analysis. The new liquid solidifies on cooling, appears to melt at 51 degrees C, and has a composition corresponding to a dihydrate. However, no solid hydrate can be detected by XRD, and it is shown that the true explanation is that a liquid-liquid phase separation occurs above 51 degrees C where the vanillin-rich phase has a composition close to a dihydrate. To our knowledge, liquid-liquid phase separation has not previously been reported for the system vanillin-water, even though thousands of tonnes of vanillin are produced globally every year.

  • 9.
    Svärd, Michael
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Valavi, Masood
    Khamar, Dikshitkumar
    Kuhs, Manuel
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Thermodynamic Stability Analysis of Tolbutamide Polymorphs and Solubility in Organic Solvents2016In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 105, no 6, 1901-1906 p.Article in journal (Refereed)
    Abstract [en]

    Melting temperatures and enthalpies of fusion have been determined by differential scanning calorimetry (DSC) for 2 polymorphs of the drug tolbutamide: FIH and FV. Heat capacities have been determined by temperature-modulated DSC for 4 polymorphs: FIL, FIH, FII, FV, and for the supercooled melt. The enthalpy of fusion of FII at its melting point has been estimated from the enthalpy of transition of FII into FIH through a thermodynamic cycle. Calorimetric data have been used to derive a quantitative polymorphic stability relationship between these 4 polymorphs, showing that FII is the stable polymorph below approximately 333 K, above which temperature FIH is the stable form up to its melting point. The relative stability of FV is well below the other polymorphs. The previously reported kinetic reversibility of the transformation between FIL and FIH has been verified using in situ Raman spectroscopy. The solid-liquid solubility of FII has been gravimetrically determined in 5 pure organic solvents ( methanol, 1-propanol, ethyl acetate, acetonitrile, and toluene) over the temperature range 278 to 323 K. The ideal solubility has been estimated from calorimetric data, and solution activity coefficients at saturation in the 5 solvents determined. All solutions show positive deviation from Raoult's law, and all van't Hoff plots of solubility data are nonlinear. The solubility in toluene is well below that observed in the other investigated solvents. Solubility data have been correlated and extrapolated to the melting point using a semiempirical regression model.

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