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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 14 (1997), S. 810-814 
    ISSN: 1573-904X
    Keywords: formoterol ; radiation treatment ; ESR spectroscopy ; dosimetry ; storage ; HPLC ; degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Radiation sterilization is becoming increasingly popular for the sterilization of many pharmaceutical products. We have investigated the gamma radiation induced effects on formoterol fumarate by HPLC and ESR spectroscopy. Results and Discussion. Numerical simulation of the evolution of the ESR signal versus dose was performed using linear regression, quadratic fit and power function. The shape of the dosimetric curve is linear in the range 5−30 kGy. Owing to the weak number of free radicals generated during the irradiation, the accuracy of measurements is low. For a dose of 25 kGy, discriminating irradiated from unirradiated samples is possible if the storage period is less than 250 days. The comparison between chromatographic profiles of irradiated and unirradiated samples showed minor differences. Conclusions. From our preliminary results, radiosterilization of formoterol fumarate may be technically feasible. Estimation of the irradiation dose by ESR may be possible but, due to the weak number of free radicals generated during the irradiation, the accuracy of measurements appeared low.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 14 (1997), S. 1186-1191 
    ISSN: 1573-904X
    Keywords: radiosterilization ; ascorbic acid ; ESR ; dosimetry ; decay of radicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. As an alternative to heat and gas exposure sterilization, ionizing radiation is gaining interest as a sterilization process for medicinal products. The aim of this work was to develop equations to describe the ESR curves versus dose and storage time after gamma irradiation of ascorbic acid. Several ESR data sets previously acquired in this laboratory were adopted to check the performance of the models. Results. Limit of detection and limit of discrimination are respectively 0.5 kGy and 2 kGy for ascorbic acid. Linear regression is applicable for doses lower than 25 kGy. Since the radiation dose selected must always be based upon the bioburden of the products and the Degree of Sterility required (ANSI/AAMI/ISO 11137), doses in the range 5−25 kGy could be investigated and linear regression would appear to be the least expensive route to follow and gives good results. Quadratic fit, power function, exponential function and bi-exponential functions are of more general applicability to predict irradiation dose. Decay kinetics for radicals versus storage were considered. Nonhomogeneous kinetics with time-dependent rate (diffusion-controlled second-order reaction) and bi-exponential function appeared valid to reproduce the experimental data. Discrimination between irradiated and unirradiated ascorbic acid is possible after a storage of 800 days. Conclusions. It is worth noting that, at present, ESR is the only technique which proves to be suitable for identification and quantification purposes in irradiated pharmaceuticals. Moreover, other features such as sensitivity, precision, ease and non-destructive readout make ESR superior to other proposed analytical techniques.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 14 (1997), S. 1192-1196 
    ISSN: 1573-904X
    Keywords: dopamine ; norepinephrine ; radiation treatment ; ESR spectroscopy ; dosimetry ; storage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Radiation sterilization is becoming increasingly popular for the sterilization of many pharmaceutical products. We have investigated the gamma radiation induced effects on dopamine and norepineprine by ESR spectroscopy. Results and Discussion. Equations to describe the evolution of the ESR curves versus doses and time of storage are presented. Linear regression is, for dopamine hydrochloride, applicable for doses ranging from 10 to 25 kGy. Since the radiation dose selected must always be based upon the bioburden of the products and the degree of sterility required, doses in the range 10−25 kGy could be investigated and linear regression would appear to be the least expensive route to follow and gives good results. The comportment of noradrenaline bitartrate is more complex and the use of linear regression would appear more hazardous especially for low doses. For doses higher than 25 kGy, a more general equation is required. Power function using only 2 parameters could give good results but must be validated. Decay kinetics for radicals versus storage were considered. Non-homogenous kinetics with time dependent rate constant and bi-exponential function appeared valid to reproduce the decay of radicals for, respectively, dopamine and norepinephrine. Conclusions. It is worth noting that, at present, ESR is the only technique which proved to be suitable for identification and quantification purposes in irradiated pharmaceuticals. Moreover, other features such as sensitivity, precision, ease and non-destructive readout make ESR superior to other proposed analytical techniques.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1920
    Keywords: Key words Lhermitte-Duclos disease ; Dysplastic gangliocytoma ; Magnetic resonance imaging ; Syringomyelia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 23-year-old man presented with a 2-week history of intracranial hypertension. CT showed a large, nonenhancing cerebellar mass with surrounding calcification and displacement of the fourth ventricle. MRI revealed a septate lesion, with low signal on T1-weighted and high signal on T2-weighted images. The cerebellar tonsils were displaced below the foramen magnum and there was associated syringomyelia. The MRI features were characteristic of Lhermitte-Duclos (LD) disease (dysplastic gangliocytoma) and the diagnosis was confirmed following surgery. In this case, we emphasise the usefulness of MRI in the diagnosis of LD disease and consider the possible pathogenesis of the associated syringomyelia.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1920
    Keywords: Lhermitte-Duclos disease ; Dysplastic gangliocytoma ; Magnetic resonance imaging ; Syringomyelia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 23-year-old man presented with a 2-week history of intracranial hypertension. CT showed a large, nonenhancing cerebellar mass with surrounding calcification and displacement of the fourth ventricle. MRI revealed a septate lesion, with low signal on T1-weighted and high signal on T2-weighted images. The cerebellar tonsils were displaced below the foramen magnum and there was associated syringomyelia. The MRI features were characteristic of Lhermitte-Duclos (LD) disease (dysplastic gangliocytoma) and the diagnosis was confirmed following surgery. In this case, we emphasise the usefulness of MRI in the diagnosis of LD disease and consider the possible pathogenesis of the associated syringomyelia.
    Type of Medium: Electronic Resource
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