The purpose of this research was to formulate tasteless complexes of ciprofloxacin with Indion 234 and to evaluate molecular properties of drug complexes. The effect of batch and column process, complexation time, temperature, and pH on ciprofloxacin loading on Indion 234 is reported. Drug resin complexes (DRC) were characterized by infrared spectroscopy, thermal analysis, and x-ray diffraction pattern. Ciprofloxacin release from DRC is obtained at salivary and gastric pH and in the presence of electrolytes. The efficient drug loading was evident in batch process using activated Indion 234 with a drug-resin ratio of 1:1.3. Drug complexation enhanced with pH from 1.2 to 6, while temperature did not affect the complexation process. Infrared spectroscopy revealed complexation of -NH (drug) with Indion 234. DRC are amorphous in nature. Drug release from DRC in salivary pH was insufficient to impart bitter taste. Volunteers rated the complex as tasteless and agreeable. Complete drug release was observed at gastric pH in 2 hours. The drug release was accelerated in the presence of electrolytes. Indion 234 is inexpensive, and the simple technique is effective for bitterness masking of ciprofloxacin.

The polyethylene glycol (PEG) treatment of ciprofloxacinIndion 234 complex was aimed to retard rapid ion exchange drug release at gastric pH. Ciprofloxacin loading on Indion 234 was performed in a batch process, and the amount of K + in Indion 234 displaced by drug with time was studied as equilibrium constant K DM . Drug-resin complex (DRC) was treated with aqueous PEG solution (0.5%-2% wt/vol) of different molecular weights (MWs) for 2 to 30 minutes. The PEG-treated ciprofloxacin-Indion 234 complex was evaluated for particle size, water absorption time, and drug release at gastric pH. During drug loading on Indion 234, the equilibrium constant (K DM ) increased rapidly up to 20 minutes with efficient drug loading. Increased time of immersion of the drug resinate in PEG solutions significantly retained higher size particles upon dehydration. The larger DRC particles showed longer water absorption times owing to compromised hydrating power. The untreated DRC showed insignificant drug release in deionized water; while at gastric pH, ciprofloxacin release was complete in 90 minutes. A trend of increased residual particle size, proportionate increase in water absorption time, and hence the retardation of release with time of immersion was evident in PEG-treated DRC. The time of immersion of DRC in PEG solution had predominant release retardant effect, while the effect of molecular weight of PEG was insignificant. Thus, PEG treatment of DRC successfully retards ciprofloxacin ion exchange release in acidic pH.