ANALYTICA CHIMICA ACTA, 1994, VOL. 289, PP. 87-95

Automated Flow-injection Serial Dynamic Dialysis Technique in the Study of Drug Binding with Cyclodextrins

E.E. Sideris^a, C.A. Georgiou^b, M.A. Koupparis*^,b, P.E. Macheras^a
aDepartment of Pharmacy, University of Athens, Panepistimiopolis, Kouponia, Athens 15771, Greece
^bDepartment of Chemistry, University of Athens, Panepistimiopolis, Kouponia, Athens 1S771, Greece

A flow-injection dynamic dialysis technique is presented for the determination of binding parameters of drugs to cyclodextrins (CDs). The automated system consists of a flow-injection unit, the sample loop of which is the receiving compartment of a dialyser unit, and a home made timing module for operation control through two flow switching solenoid valves. The procedure of binding studies is rapid and yields reproducible results. Binding parameters of CD-micromolecule complexes were calculated using the Scatchard model. Typical examples of the binding of p-nitrophenol with a-CD (K_as = 1.58 x 10³ M^-1 at pH 7.4 and 2.06 x 10³ M^-1 at pH 9.0), salicylic acid with b-CD (K_as = 3.8 x 10² M^-1 at pH 1.5 and 51 M^-1 at pH 7.4) and ibuprofen with b-CD (K_as = 2.2 x 10² M^-1 at pH 2.5) are presented and the binding constants obtained are compared to literature values.1:1 stoichiometry was found in all cases and within run precision ranged from 2 to 14% R.S.D. The between run precision for the binding of p-nitrophenol to a-CD was 2% (n = 3).

Keywords: Flow injection; automated serial dynamic dialysis technique; cyclodextrins; drug binding to cyclodextrins; ibuprofen; p-nitrophenol; salicylic acid; scatchard model

* Corresponding author.
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Questions and comments to author: Dr C.A. Georgiou, cag@aua.gr
Phone: +3010-5294248, fax: +3010-5294265
Chemistry Laboratory, Agricultural University of Athens, Greece