PRELIMINARY PREFORMULATION STUDIES FOR A NEW NORFLOXACIN RUTHENIUM (III) COMPLEX WITH BIOLOGICAL ACTIVITY
CRISTINA DINU PÎRVU1, CORINA CRISTINA ARAMĂ2*, CLAUDIU RADU2, VALENTINA UIVAROSI3
1Department of Physical and Colloidal Chemistry, Faculty of Pharmacy, Carol Davila University of Medicine and Pharmacy, 6 Traian Vuia St., 020956 Bucharest, Romania
2Department of Analytical Chemistry, Faculty of Pharmacy, Carol Davila University of Medicine and Pharmacy, , 6 Traian Vuia St., 020956 Bucharest, Romania
3Department of General and Inorganic Chemistry, Faculty of Pharmacy, Carol Davila University of Medicine and Pharmacy, 6 Traian Vuia St., 020956 Bucharest, Romania
* corresponding author: corinarama@yahoo.com
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Abstract:

Most of the newly synthesized compounds with biological activity show a low solubility in water, which is inconvenient for the pharmaceutical formulation process. The present study is intended to evaluate the possibilities to improve the solubility of a new biologically active complex formed by Ru(III) with an antimicrobial drug, norfloxacin. Three strategies have been used in order to achieve an enhancement of solubility: pH adjustment/salt formation, use of co-solvents, forming of cyclodextrin inclusion complexes. The solubility profile of Ru(nf)2Cl3(DMSO)·H2O was studied in the pH range 4.4 – 9.4 and shows that its solubility is almost unaffected in acidic medium, but increases in basic solutions due to the soluble salt formation. Solubility was increased also in binary systems water - biocompatible organic co-solvent (propylene glycol, polyethylene glycol 400), as well in a ternary system water - propylene glycol - ethanol. In the experiments using cyclodextrins, the phase-solubility diagrams indicated an enhancement of the complex solubility in the presence of beta-cyclodextrin, as well as its derivative, sulfobutylether-beta-cyclodextrin.

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