Characterization and in vitro drug release studies of a natural polysaccharide Terminalia catappa gum (Badam gum)

Abstract

The main objective of the present study is the physicochemical characterization of naturally available Terminalia catappa gum (Badam gum [BG]) as a novel pharmaceutical excipient and its suitability in the development of gastroretentive floating drug delivery systems (GRFDDS) to retard the drug for 12 h when the dosage form is exposed to gastrointestinal fluids in the gastric environment. As BG was being explored for the first time for its pharmaceutical application, physicochemical, microbiological, rheological, and stability studies were carried out on this gum. In the present investigation, the physicochemical properties, such as micromeritic, rheological, melting point, moisture content, pH, swelling index, water absorption, and volatile acidity, were evaluated. The gum was characterized by scanning electron microscopy, differential scanning calorimetry (DSC), powder X-ray diffraction studies (PXRD), and Fourier transform infrared spectroscopy (FTIR). Gastroretentive floating tablets of BG were prepared with the model drug propranolol HCl by direct compression methods. The prepared tablets were evaluated for all their physicochemical properties, in vitro buoyancy, in vitro drug release, and rate order kinetics. PBG 04 was selected as an optimized formulation based on its 12-h drug release and good buoyancy characteristics. The optimized formulation was characterized with FTIR, DSC, and PXRD studies, and no interaction between the drug and BG was found. Thus, the study confirmed that BG might be used in the gastroretentive drug delivery system as a release-retarding polymer.

Fig. 1

Particle size distribution of BG powder

Fig. 2

SEM photographs of BG powder

Fig. 3

DSC thermogram of BG powder

Fig. 4

FTIR spectra of BG powder

Fig. 5

X-ray diffractogram of BG powder

Fig. 6

a Shear stress vs. shear rate and b shear rate vs. viscosity profiles of various concentrations of BG

Fig. 7

Comparison of shear rate vs. viscosity profiles of 1.5% and 2% w/v BG stored at normal conditions for 1 year

Fig. 8

Dissolution profiles of BG–propranolol HCl floating tablets

Fig. 9

FTIR spectra of a propranolol HCl, b BG, and c PBG 04

Fig. 10

DSC thermogram of a propranolol HCl, b BG, and c PBG 04

Fig. 11

PXRD diffractogram of a propranolol HCl, b BG, and c PBG 04