title: Stability improvement of alpha-amylase entrapped in kappa-carrageenan beads: physicochemical characterization and optimization using composite index.
abstract: OBJECTIVE
  This work examines the influence of various process parameters on alpha-amylase entrapped in crosslinked kappa-carrageenan beads for stability improvement. A three level full factorial design was employed to investigate the effect of three process variables namely kappa-carrageenan concentration, potassium chloride concentration and hardening time on % entrapment, time required for 50% (T50) and 90% (T90) of enzyme release and particle size.
  
  
  METHODS
  The beads were prepared by dropping the kappa-carrageenan-containing alpha-amylase to magnetically stirred potassium chloride solution. The composite index was applied to optimize the process under study. 'In vitro' enzyme release profile of the beads was fitted to various release kinetics models to understand the release mechanism. Topographical characterization was carried out by SEM and entrapment was confirmed by FTIR and DSC. Stability testing according to the ICH guidelines for zone III and IV was carried out.
  
  
  RESULTS
  With the use of ionotropic gelation method, a polymeric matrix prepared by 3.5% (w/v) kappa-carrageenan, 0.7 M potassium chloride and hardening time of 30 min resulted in the production of beads characterized by disc shaped with collapsed center, absence of aggregates, % entrapment of 73.79, T90 of 74.4 min, and composite index of 83.01. Moreover, shelf-life of the enzyme loaded beads was found to increase up to 3.53 years compared to 0.99 year of the conventional formulation.
  
  
  CONCLUSIONS
  It can be inferred that the proposed method can be used to prepare alpha-amylase loaded kappa-carrageenan beads for stability improvement. Also the proper selection of rate-controlling carrageenan concentration and its interactive potential for crosslinking is important and will determine the overall size and shape of beads, the duration and pattern of dissolution profiles and enzyme loading capacity.
authors.affiliation: Centre of Relevance and Excellence in Novel Drug Delivery Systems, Pharmacy Department, G.H. Patel Building, The M.S. University of Baroda, Vadodara 390002, India. sankalia_mayur@hotmail.com
authors.forename: Mayur G
authors.initials: MG
authors.lastname: Sankalia
authors.forename: Rajshree C
authors.initials: RC
authors.lastname: Mashru
authors.forename: Jolly M
authors.initials: JM
authors.lastname: Sankalia
authors.forename: Vijay B
authors.initials: VB
authors.lastname: Sutariya
mesh_terms: D002152:Calorimetry, Differential Scanning; D002351:Carrageenan / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical; D004349:Drug Packaging; D004355:Drug Stability; D004795:Enzyme Stability; D004800:Enzymes, Immobilized; D005765:Gastrointestinal Agents / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010316:Particle Size; D011189:Potassium Chloride / Q000737:chemistry; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D000516:alpha-Amylases / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D005765:Gastrointestinal Agents; D011189:Potassium Chloride; D002351:Carrageenan; D000516:alpha-Amylases