Characterization of succinylated β-lactoglobulin and its application as the excipient in novel delayed release tablets

Succinylated β-lactoglobulin as the excipient in delayed release tablets was studied in vitro. Succinylation decreased protein solubility and protein charge density at acidic pH and increased solubility and zeta potential at pH > 5.2. While rate of protein succinylation is increased, tablet erosion (protein loss) was decreased at pH 1.2 and increased at pH 7.5. Consequently in gastric conditions, tablets of protein succinylated by 50% or 100% took 2 h to release 15% and 6.6% of loaded riboflavin, respectively. In intestinal conditions, riboflavin was released within 1 h for all tablets. Succinylation of β-lactoglobulin also provided a buffering effect inside the tablets, maintaining the pH > 6 after 3 h in simulated gastric fluid with pepsin. Succinylated proteins showed the same cytotoxicity as native β-lactoglobulin (IC50 > 5 mg mL−1). This work highlighted the potential of succinylated β-lactoglobulin as a functional excipient for the design of oral controlled-release tablets.