ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Use of sub-ambient DSC to complement conventional DSC and TG (1997)
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 907-912 
    Details
    ISSN: 1572-8943
    Keywords: bound water ; drug substance ; excipients ; freezable water ; hydrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Several drug substances or excipients are hygroscopic. The uptake or loss of water of such substances is generally difficult to control during processing or storage of drug products. DSC instruments with sub-ambient temperature equipment allow the determination of the amount of freezable water by measuring the corresponding melting enthalpy. The determination of freezable water adds valuable information complementary to TG analysis for understanding the processing and storage of raw materials and drug products. Several substances were tested as is, without treatment, after storage at 92% r.h. and after equilibration with water. The results of these experiments showed that it was possible to demonstrate defined hydrate formation, to determine the upper level of binding of water in amorphous substances and to confirm reversible hydrate formations demonstrated by temperature resolved X-ray diffraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01996776
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Study of the polymorphic behaviour of some local anesthetic drugs (1997)
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 913-927 
    Details
    ISSN: 1572-8943
    Keywords: anesthetic drugs ; bupivacaine hydrochloride ; dibucaine hydrochloride ; DSC ; polymorphism ; prilocaine hydrochloride ; procaine hydrochloride ; solvent mediated transitions ; temperature resolved X-ray diffraction ; tetracaine base ; tetracaine hydrochloride ; thermodynamic relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The local anesthetic drug tetracaine hydrochloride is described in the Europ. Pharmacopea with a melting point of 148°C or with a range of 134 to 147°C due to the melting points of two other forms. The polymorphic behaviour of tetracaine hydrochloride has been studied by using thermal treatments, storage at 92% r.h., crystallizations and equilibrations with saturated solutions. Samples were characterized by X-ray diffraction, IR, thermal analysis and elemental analysis. Since some findings were difficult to interpret, temperature resolved X-ray diffraction was used additionally for the understanding of the thermal behaviour of tetracaine hydrochloride. In this study the polymorphic behaviour of some other local anesthetic drugs is compared. Ten different forms of tetracaine hydrochloride: six anhydrous crystalline forms, an amorphous form, a hemihydrate, a monohydrate and a tetrahydrate were identified. The relationships between all forms are given. The heating curve of the commercial form 1 is very dependent on the heating rate. This anhydrous form 1 is the thermodynamic stable modification at ambient temperature. The form 2 is reversibly enantiotrope to form 1. The four other modifications called 3, 4, 5 and 6 are monotropes of form 1. Only forms 1 and 5 are stable at ambient temperature. Form 1 is hygroscopic only at high humidity level of 92% r.h., form 5 is hygroscopic at 61% r.h. Both transform into the monohy-drate. No polymorphic forms of tetracaine base, dibucaine hydrochloride, procaine hydrochloride or prilocaine hydrochloride were found. The commercial form of bupivacaine hydrochloride is a monohydrate. Thermal treatment at 200°C gives one anhydrous form. As demonstrated by temperature resolved X-ray diffraction two other forms are detected by heating and cooling processes between 100 and 170°C. Equilibrations and crystallization experiments show that solvates are easily obtained in different solvents. Temperature resolved X-ray diffraction is a very efficient tool as a support to DSC for the identification of the transition processes and interpretation of thermal events and thermodynamic relationships. Equilibration experiments are very adequate to find out the thermodynamically stable form at ambient temperature (solvent mediated transitions).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01996777
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Use of DSC and TG for identification and quantification of the dosage form (1997)
    Springer
    Journal of thermal analysis and calorimetry 48 (1997), S. 473-483 
    Details
    ISSN: 1572-8943
    Keywords: dosage form ; drug products ; DSC ; identification ; quantitation ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal analysis techniques, DSC and TG can advantageously be used in quality control of drug products. The methods are commonly used in preformulation for the study of polymorphism and for the study of the interactions drug substance-excipients, since these physical interactions can be the basis of the dosage form performance. For routine control of the drug products, DSC and TG methods which are quick, which require only few mg of the samples and which are automated, are very attractive for routine analysis of drug products. A single scan can give several qualitative and quantitative informations. DSC offer analytical possibilities only if the drug substance and the excipients do not have physical interactions or limited interactions (e.g. eutectic behaviour). About twenty marketed products have been analyzed by DSC and TG. In most of them identification of drug substance is easy. Several excipients could be identified in a tablet. Quantitations are demonstrated for some drug substances and excipients. DSC purity calculations have been applied to acetyl salicylic acid, paracetamol, cimetidine, pindolol, ibuprofen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01979494
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Thermal Analysis, Microcalorimetry and Combined Techniques for the Study of the Polymorphic Behaviour of a Purine Derivative (1999)
    Springer
    Journal of thermal analysis and calorimetry 57 (1999), S. 61-73 
    Details
    ISSN: 1572-8943
    Keywords: amorphous ; combined techniques for polymorphism ; DSC ; MKS 492 ; polymorphism ; purine ; quantitative determination ofamorphous and polymorphs ; solvent mediated transitions ; temperature resolved X-ray diffraction ; TG ; thermodynamic relation between polymorphs ; xanthine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The polymorphic behaviour of the purine derivative MKS 492 was studied with investigations of suspensions of selected samples in different solvents and of samples obtained by crystallizations. The samples were analyzed by DSC, TG and X-ray diffraction. Six different crystalline modifications called A, B, B’, C, D and E and an amorphous form were identified. Four pure crystalline modifications, A, B, C and D have been manufactured and characterized by DSC, X-ray, IR, solubilities, densities, hygroscopicity and dissolution measurements. The four forms A, C, D and E are monotrop to the form B. The form B is enantiotrop to the form B’, which revealed the highest melting point of all known polymorphs. This form B’ is only stable at high temperature. Temperature resolved X-ray diffraction was very helpful for proper interpretation of the thermal events. The melting peaks of the forms A and C and the endothermic peak corresponding to the enantiotropic transition B into B’ occur in a narrow range of temperature. The form B which is the most stable one at room temperature has been chosen for further development. Quantitative methods to determine the content of the forms A, C and D in samples of form B or to determine the content of form A, B and D in form C have been developed by using X-ray diffraction. Limits of detection are 1 or 2%. For the quantitative determination of the amorphous fraction, X-ray diffraction and microcalorimetry are compared. For high amounts of the amorphous fraction, the X-ray diffraction method is preferred because it is faster. Microcalorimetry is very attractive for levels below 10% amorphous content. The lowest limit of detection is obtained by microcalorimetry, about 1%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010145125531
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...