Studies on Span based Soy-bigels with HPMC

Abstract

Organogels owing to their lipophilic nature and better stability over other gel preparations may have a wide range of application but leaching of oily phase restricts their application. Use of hydrogel is limited by its stability problems and syneresis at atmospheric condition. Attempts to overcome such drawbacks can be overcome by combining both lipophilic organogel and hydrophilic hdydrogel phases in a single formulation, bigel. The present study deals with the development and evaluation of soy-bigel by mixing organogel of soybean oil (prepared with Span 40 or Span 60) and hydrogel of HPMCK4M or HPMCK15M in a definite ratio. Four batches of soy-bigels were prepared by mixing organogel with 18%w/v Span and 3% HPMC hydrogel. Formulations were examined for compatibility by FTIR spectroscopy, characterized for physical appearance, pH, rheological behavior, in vitro drug release pattern and thermal stability study. FTIR study confirmed compatibility between paracetamol and components of bigel. Soy-bigels were found to possess satisfactory organoleptic properties and applicability parameters and demonstrated pseudoplastic flow behavior. Better drug release was observed in soy-bigel prepared with Span 40 and HPMCK4M (OHP2) which followed Kormeyer-Peppas model with non-Fickian diffusion. Diffusion-controlled drug release gradually decreased in gels of matrix type developed with Span 60 and either grade of HPMC (OHS1 and OHS2). Soy-bigels prepared from Span 40 and either grades of HPMC demonstrated thermal stability on exposure to 5 freeze-thaw cycles. Thus, soy-bigels prepared from Span 40 and HPMCK4M exhibited satisfactory rheological property and improved drug release and can ideally be selected as a topical base for drug delivery.