Studies on Bio-adhesion of Matrix Tablets: II.Comparison on Bio-adhesion Strength and Release Profiles of Theophylline Anhydrous and Its Sodium Glycinate Salt

Abstract

Controlled release matrix tablets of Theophylline anhydrous and Theophylline sodium glycinate were
prepared with different types of bio-adhesive polymers e.g. HPMC 15 & 50 cps, Gelatin, PVP K-30, Na-CMC and
Xanthan gum. Tablets, prepared by direct compression method were subjected to in-vitro drug dissolution for 8 hours
in 0.1 N hydrochloric acid (pH 1.2) using a thermal shaker at 50 rpm at 37 ± 0.5ºC. The bio-adhesive property was
investigated in terms of retention time following in-vitro wash-off method by Lehr et al. The anhydrous and
corresponding salt form was used to investigate whether physical variation of Theophylline molecule can cause any
change in release and bio-adhesion property or not. In most of the cases it is found that salt form releases greater
percentage of active drug than its corresponding anhydrous form. Irrespective of drug’s physical property and amount
of polymer, bio-adhesive strength of Xanthan gum was proved to be maximum followed by HPMC- 50 cps, Na-CMC
and HPMC- 15 cps, whereas gelatin and PVP K-30 showed little or poor muco-adhesion. Xanthan gum, Na-CMC
and HPMC based formulations showed nearly zero-order release; on the contrary PVP K-30 based formulation
showed a burst release within one hour of dissolution.