The Effect of Chitosan Type and Concentration on Physical Characteristics and Drug Release Behavior of Andrographolide-Chitosan Microparticles Prepared by Ionic Gelation – Freeze Drying

Abstract

Andrographolide is low in solubility and bioavailability, with short half-life (t1/2 = 1.5-2 hours), with chitosan micro-particles expected to improve its dissolution. Therefore, the objective of this research was to investigate the effect of chitosan concentration and the in vitro release of andrographolide from micro-particles prepared by ionic gelation using sodium tripolyphosphate (TPP) as cross-linker. Furthermore, the micro-particles used were prepared with two different concentration of chitosan namely 19 cPs and 50 cPs. The result showed that the micro-particles obtained were spherical in shape and heterogeneous in size, with Infrared spectra indicating ionic bonding between chitosan and TPP. The DTA thermogram and XRD diffractogram exhibited a change in crystal structure to a more amorphous form. The entrapment efficiency (EE) of andrographolide in micro-particles was about 78%, with no impact on the chitosan concentrations (19 cPs and 50 cPs) affected by EE. The kinetics released was followed by the Higuchi model in phosphate buffer, with pH 7 ± 0,05 higher than the andrographolide substance. It was investigated that andrographolide-chitosan micro-particles had the ability to enhance its dissolution rate.

Keywords: microparticle, andrographolide, chitosan, ionic gelation, drug release