Poly (vinyl alcohol)/chitosan cryogels as PH responsive ciprofloxacin carriers

The pH responsiveness of swelling behavior and the release of ciprofloxacin hydrochloride from poly (vinyl alcohol)/chitosan cryogels of various compositions were investigated. All cryogels swelled and reached equilibrium within 100 min, indicating that the cryogels swell relatively fast. Increasing the chitosan content in the poly (vinyl alcohol) cryogels increased the swelling capacity of the cryogels. The poly (vinyl alcohol)/chitosan cryogels exhibited a sudden change in swelling characteristics at a certain pH value of the swelling medium as critical pH of 6.37–6.68 which depends on chitosan content. Ciprofloxacin hydrochloride was loaded into poly (vinyl alcohol)/chitosan cryogels to study its in-vitro release. Drug release behavior was found to be pH-dependent. The release mechanism changes with pH of the medium and mainly at critical pH. The release rate is high in acidic medium (pH 4.5 and 5.5) as compared with basic one (pH 7.4), in the last pH medium the drug being delivered in a prolonged period and with a slow release rate. The pH responsiveness indicates that these systems are interesting drug carriers for the oral formulations or as wound dressing materials.