Citric acid prolongs the gastro-retention of a floating dosage form and increases bioavailability of riboflavin in the fasted state

A floating dosage form based on calcium alginate beads has been developed. Riboflavin, was selected as the model drug and successfully incorporated into calcium alginate beads. The aims of the current study were to: (a) assess the influence of prolonged gastro-retention on the bioavailability of riboflavin from freeze dried calcium alginate beads administered under varying conditions of food intake and (b) to investigate the potential of citric acid to delay the gastric emptying of the calcium alginate beads. Gamma scintigraphy was selected as the method to monitor the movement of the calcium alginate beads in vivo. Riboflavin concentrations in the urine were analysed by HPLC. Prolonged gastro-retention can be achieved, in the fasted state, when citric acid solution is used as an administering vehicle. However, prolonged gastro-retention is not achieved to the same extent when the gastric emptying times are compared to those obtained in the fed state. The bioavailability of riboflavin improved when calcium alginate beads were administered in the fasted state with citric acid solution, compared to the bioavailability obtained when the calcium alginate beads were administered in the absence of citric acid.