Inulin-Grafted Stearate (In-g-St) as the Effective Self-Assembling Polymeric Micelle: Synthesis and Evaluation for the Delivery of Betamethasone

Background. Betamethasone as a corticosteroid drug is commonly used for the treatment of rheumatoid arthritis. Unfortunately, betamethasone is a low water-soluble drug and its efficacy is low. So an attractive strategy is the targeted delivery of betamethasone to the damaged joint using polymeric micelle-based carriers. Methods. Inulin-grafted stearate (In-g-St) was synthesized via the reaction of stearoyl chloride and inulin, then characterized by FT-IR and H-NMR. In-g-St forms micelles in the presence of betamethasone. The prepared polymeric micelles were characterized for size, zeta potential, drug loading, particles’ morphology, critical micelle concentration (CMC), and encapsulation efficiency. So sustained release polymeric micelles of betamethasone were developed by employing In-g-St. Results. The measurement of particle size showed a mean diameter of 60 and 130 nm for 10% and 20% drug-loaded micelles, respectively, and SEM showed that the particle’s morphologies are spherical. Zeta potential measurement for the drug-containing micelles showed a value of -11.8 mV. Drug loading efficiency and the encapsulation efficiency were 6.36% and 63.6%, as well as 18.97% and 94.88% for 10% and 20%, respectively. 20% drug-loaded polymer showed a small burst release of betamethasone at the first 3 h which was followed by sustained release in the next 24 h. Furthermore, the formula with 10% exhibited good sustained release properties except for the minor initial burst release. Conclusion. Data from the zeta potential, CMC, drug loading capacity, and in vitro drug release studies indicated that In-g-St polymeric micelles can be suitable candidates for the efficient delivery of hydrophobic drugs like betamethasone.