Document Detail

Effects of harvesting and cooling on crystallization and transformation of orthorhombic paracetamol in ethanolic solution.
MedLine Citation:
PMID:  12356416     Owner:  NLM     Status:  MEDLINE    
Orthorhombic paracetamol (form II) can be obtained from ethanolic solution when seeding technique is applied although it converts to monoclinic (form I) upon contact with the solvent. In the present work different cooling temperature T(C) (-20, -10 and 0 degrees C) was applied under fixed agitation (700 rpm) and the crystalline product was harvested after different crystallization time t(H) (20, 30 and 40 min). Crystal yield (Y%), micromeritic properties and orthorhombic content of the crystalline product were evaluated and related to T(C) and t(H). Conditions for optimal crystal yield and orthorhombic content were elucidated and kinetic parameters of solvent mediated transformation (induction times, t(it), and activation energy, E(a)) were determined. It was found that crystal yield (Y%) increases with t(H) and decreases with T(C). The mean crystal size and size distribution is affected linearly by T(C), probably due to alterations in the nucleation and growth processes. The effects on the crystal shape can be elucidated only after size classification. As the crystals grow, they become more elongated, with rougher surface due to secondary nucleation and alteration in growth rate of different crystal faces. Induction times for solvent mediated transformation (t(it)), were remarkably longer than those corresponding to appearance of monoclinic form, when large scale collection and drying of crystalline product was applied, probably due to residual solvent evaporation. The activation energy of solvent mediated transformation (E(a)=62.9 kJ/mol) is between those for nucleation in the solid state and in a solvent, indicating the operation of a mixed mechanism.
N Al-Zoubi; K Kachrimanis; S Malamataris
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences     Volume:  17     ISSN:  0928-0987     ISO Abbreviation:  Eur J Pharm Sci     Publication Date:  2002 Oct 
Date Detail:
Created Date:  2002-10-01     Completed Date:  2003-04-21     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9317982     Medline TA:  Eur J Pharm Sci     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  13-21     Citation Subset:  IM    
Copyright Information:
Copyright 2002 Elsevier Science B.V.
Department of Pharmaceutical Technology, School of Pharmacy, University of Thessaloniki, Thessaloniki 54006, Greece.
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MeSH Terms
Acetaminophen / chemistry*
Cold Temperature
Ethanol / chemistry*
Pharmaceutical Solutions
Technology, Pharmaceutical / methods*
Reg. No./Substance:
0/Pharmaceutical Solutions; 103-90-2/Acetaminophen; 64-17-5/Ethanol

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