Design and Evaluation of Novel Sustained-Release Floating Microspheres for Oral Delivery of Ciprofloxacin Hydrochloride

Ciprofloxacin (CIP) is a broad-spectrum antibiotic, used to treat various bacterial infections. Administration of conventional oral dosage forms of CIP is associated with multiple challenges such as short residence time of the drug in the gastrointestinal tract which could reduce bioavailability and effectiveness of the drug. This study aimed to design and develop novel floating microspheres for the sustained release of CIP in the stomach over 24 hours after oral administration, besides evaluating the effect of different variables on the characteristics of developed microspheres.

Microspheres were developed by the solvent-evaporation method utilizing cellulose acetate and polyvinyl alcohol, then characterized for physicochemical properties including bulk density, buoyancy, and entrapment efficacy. The drug-excipient compatibility was evaluated by Fourier-transform infrared spectroscopy and the Scanning electron microscopy was used to observe the morphology of microspheres. The effects of the drug to polymer ratio, polymer concentration, and the pace of stirring through the preparation process, on the size and release rate were also evaluated.

Morphology analysis indicated round-shape microspheres with a mean particle size between 66-344 µm. The polydispersity index of prepared formulations was determined to be in the range of 0.129 to 0.230. It was observed that at higher polymer concentrations the drug release rate from microspheres decreased while the mean particle size increased. Increasing the drug to polymer ratio and decreasing the stirring speed increased the mean particle size. All formulations showed more than 70% cumulative drug release in the prolonged period of 24 h while remaining buoyant in the meantime. The formulations followed Higuchi and Korsmeyer-Peppas kinetics and release the drug by diffusion mechanism.

Based on the results obtained from in vitro release study besides floating properties, the prepared microspheres could be considered suitable for enhanced sustained-release of CIP following the oral administration.