title: Complexation between risperidone and amberlite resin by various methods of preparation and binding study.
abstract: OBJECTIVE
  The purpose of this work was to investigate the effect of preparation methods and the drug-to-resin ratio on complex formation between risperidone and amberlite resin.
  
  
  METHODS
  The existence of such resin complex may provide taste-masking properties to the dosage forms. It is important to determine when and how the complex forms. Therefore, in this study, the complexes of risperidone and amberlite resin were prepared by granulation, solution, and freeze-drying methods at various drug-to-resin ratios. The physical mixtures of drug-resin were used to compare the results of complexes prepared by granulation, solution, and freeze drying. The complexes were evaluated by various methods of characterization including differential scanning calorimetry, X-ray diffraction, spectroscopy (near infrared, Fourier transform infrared, and Raman), drug release, and binding studies.
  
  
  RESULTS
  Complexation between risperidone and amberlite was investigated for various preparation methods. It was found that complexation occurred at lower amounts of amberlite resin (drug-to-resin ratios of 1:1 and 1:2) when solution form of drug was contacted with the resin as in the case of solution and freeze-drying techniques compared with granulation (drug-to-resin ratios of 1:4 and 1:6). Characterization studies such as differential scanning calorimetry, X-ray diffraction, spectroscopic techniques, and drug release studies differentiated complexes from the physical mixtures. Binding studies between them revealed that the binding was linear with solubility of the drug limiting the adsorption capacity.
  
  
  CONCLUSIONS
  Results of the study highlighted the importance of the preparation methodologies to formulate complexes. When the drug and the resin were simply mixed physically, no complexation occurred. Thus, a careful evaluation of manufacturing procedure would indicate the nature and extent of complexation.
authors.affiliation: Division of Product Quality Research, Office of Testing and Research, Office of Pharmaceutical Sciences, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993, USA.
authors.forename: Rakhi B
authors.initials: RB
authors.lastname: Shah
authors.forename: Mobin A
authors.initials: MA
authors.lastname: Tawakkul
authors.forename: Vilayat A
authors.initials: VA
authors.lastname: Sayeed
authors.forename: Mansoor A
authors.initials: MA
authors.lastname: Khan
mesh_terms: D000327:Adsorption; D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D007700:Kinetics; D033362:Powder Diffraction; D012117:Resins, Synthetic / Q000737:chemistry*; D018967:Risperidone / Q000737:chemistry*; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D019265:Spectroscopy, Near-Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D012117:Resins, Synthetic; C046797:amberlite; D018967:Risperidone