Hi,Back to the Top
We are trying to use 20 % Cyclodextrin in our iv formulation for
preclinical studies (NCE is insoluble in most of the solvents) . Our
concern is the release of drug from this complexating agent. how we
characterise complexation constant or get an idea of the extent of
release.
Thanks!!
John
Hi John,Back to the Top
When you cyclodextrins (CD) in IV formulation you have to be sure if
drug solubility is improved by an external solubilization effect or by
the formation of an inclusion compound between the drug and CD. To do
so you have to performe solubility studies with your drug in excess and
using increasimg amounts of CDs. If drug solubility diagram increases
with CD concentration you will have a primary indication of complex
formation. In this case, and with the data of solubility studies you
can calculate the stability constant of the resulting complex by the
equation of Higuchi and Connors. There is many similsr solubility
studies described in the literature. Having the inform,ation of the
value of the stability constant you will have an idea of the extent of
drug release.
Hope this help...
Laura Ribeiro, Ph.D Student
Laboratory of Pharmaceutical Technology
Faculty of Pharmacy
University of Coimbra
3000-004 Coimbra
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)