PREFERENTIAL SOLVATION OF NORFLOXACIN AND CIPROFLOXACIN WITH SULFANILAMIDE OR SULFAMETOXAZOLE IN MIXED BINARY SOLVENT

AVILA CD; MAZZIERI MR; PINTO VITORINO G

Otro; III Reunión Internacional de Ciencias Farmacéuticas ? RICiFa 2014; 2014

UNC y UNR

Fluoroquinolones and sulfamides are antibacterial drugs with low solubility. The solute-solvent interactions allow understand the absorption of drugs and the interactions involved in the molecular recognition. Solute may induce changes in the solvation sphere with respect of the bulk, this phenomenon is denominated preferential solvation (PS). In a mixed solvent system the maximum energy of absorption of the solute at UV-Vis spectra, depends on the composition of solvent mixture in the solvation shell. In this work, we studied the solvation of norfloxacin (NOR), ciprofloxacin (CIP), sulfanilamide (SNA), sulfamethoxazol (SMX) and equimolecular combinations of NOR-SNA, NOR-SMX, CIP-SNA and CIP-SMX in two different binary mixtures of solvents, aqueous buffer (amphiprotic):MeOH (protic) and aqueous buffer:ACN (aprotic). The solvent was buffer pH 7.4 and increasing mole fractions of MeOH or ACN. Concentrations of the solute were 5.0 x 10-5 M. The UV spectra were recorded in the range 200-400 nm. The results were analyzed by the Taft and Kamlet?s linear free energy relationship method. In buffer:ACN, all the samples showed PS by ACN, except CIP. When buffer:MeOH was used, it was not observed PS with NOR, SNA and CIP; SMX, SNA-NOR and SMX-NOR exhibited PS by buffer and SNA-CIP and SMX-CIP showed PS by MeOH. In all the samples, except for SMX-CIP in buffer:ACN, the dipole moment of the solutes decrease upon excitation. SMX, CIP and SNA-CIP are sensitive to the hydrogen bond donor ability of buffer:MeOH, and SMX, CIP, SNA-NOR and SMX-CIP are to the mixture buffer:ACN. CIP in both mixtures and SMX and SMX-CIP in buffer:ACN are affected by the hydrogen bond acceptor ability of the solvent. The molecular characteristics of this drugs produce multiple interactions with the solvent system. This methodology allows as to infer the interactions involved in the molecular recognition.