Abstract：
PURPOSE:This study was conducted to demonstrate the use of differential scanning calorimetry (DSC) in detecting and measuring beta-relaxation processes in amorphous pharmaceutical systems. METHODS:DSC was employed to study amorphous samples of poly(vinylpyrrolidone) (PVP), indomethacin (IM), and ursodeoxycholic acid (UDA) that were annealed at temperatures (T(a)) around 0.8 of their glass transition temperatures (T(g)). Dynamic mechanical analysis (DMA) was used to measure beta-relaxation in PVP. RESULTS:Reheating the annealed samples gives rise to annealing peaks that occur below T(g). The peaks cannot be generated when annealing below the low temperature limit of beta-relaxation. These limits are around 50 degrees C for PVP, -20 degrees C for IM, and 30 degrees C for UDA. The effective activation energy (E) of the sub-T(g) relaxation has been estimated for each T(a) and found to increase with T(a), reflecting increasing contribution of the alpha-process. Estimates of E for beta-relaxation have been obtained from the lowest T(a) data, and are as follows: 68 (PVP), 56 (IM), 67 (UDA) kJ mol(-1). CONCLUSIONS:DSC can be used for detecting beta-relaxation processes and estimating its low temperature limit, i.e., the temperature below which amorphous drugs would remain stable. It can also provide comparative estimates of low temperature stability of amorphous drugs in terms of the activation energies of the beta-relaxation.
journal_name
Pharm Resjournal_title
Pharmaceutical researchauthors
Vyazovkin S,Dranca Idoi
10.1007/s11095-005-9044-4subject
Has Abstractpub_date
2006-02-01 00:00:00pages
422-8issue
2eissn
0724-8741issn
1573-904Xjournal_volume
23pub_type
杂志文章abstract：:The synthesis of an homologous series of new water-soluble derivatives of pilocarpine is described. The new compounds, referred to as soft quaternary salts, are water soluble by virtue of a cationic ammonium head and their lipophilicity can be modulated by manipulating the size and the nature of the substituent in the...
journal_title：Pharmaceutical research
pub_type： 杂志文章
doi：10.1023/a:1015847103862
更新日期：1992-03-01 00:00:00
abstract：PURPOSE:Since the absorption of ceftriaxone (CTO) in the intestine is restricted by its natural physiological characteristics, we developed a series of small synthetic compounds derived from bile acids to promote the absorption of CTO in the gastrointestinal tract. METHODS:Several bile acid derivatives were screened b...
journal_title：Pharmaceutical research
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journal_title：Pharmaceutical research
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journal_title：Pharmaceutical research
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journal_title：Pharmaceutical research
pub_type： 杂志文章
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pub_type： 杂志文章
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journal_title：Pharmaceutical research
pub_type： 杂志文章
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更新日期：2017-02-01 00:00:00
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journal_title：Pharmaceutical research
pub_type： 杂志文章
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pub_type： 杂志文章,评审
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journal_title：Pharmaceutical research
pub_type： 杂志文章
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journal_title：Pharmaceutical research
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journal_title：Pharmaceutical research
pub_type： 杂志文章
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journal_title：Pharmaceutical research
pub_type： 杂志文章
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更新日期：1992-07-01 00:00:00
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journal_title：Pharmaceutical research
pub_type： 杂志文章
doi：10.1023/a:1015915812987
更新日期：1988-06-01 00:00:00
