title: Application of hanging drop technique to optimize human IgG formulations.
abstract: OBJECTIVE
  The purpose of this work is to assess the hanging drop technique in screening excipients to develop optimal formulations for human immunoglobulin G (IgG).
  
  
  METHODS
  A microdrop of human IgG and test solution hanging from a cover slide and undergoing vapour diffusion was monitored by a stereomicroscope. Aqueous solutions of IgG in the presence of different pH, salt concentrations and excipients were prepared and characterized.
  
  
  RESULTS
  Low concentration of either sodium/potassium phosphate or McIlvaine buffer favoured the solubility of IgG. Addition of sucrose favoured the stability of this antibody while addition of NaCl caused more aggregation. Antimicrobial preservatives were also screened and a complex effect at different buffer conditions was observed. Dynamic light scattering, differential scanning calorimetry and size exclusion chromatography studies were performed to further validate the results.
  
  
  CONCLUSIONS
  In conclusion, hanging drop is a very easy and effective approach to screen protein formulations in the early stage of formulation development.
authors: Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Mercer University, Atlanta, GA 30341, USA.
authors: Guohua
authors: G
authors: Li
authors: Purna C
authors: PC
authors: Kasha
authors: Sameer
authors: S
authors: Late
authors: Ajay K
authors: AK
authors: Banga
mesh_terms: D002021:Buffers; D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical / Q000379:methods; D002850:Chromatography, Gel; D004355:Drug Stability; D005079:Excipients / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007074:Immunoglobulin G / Q000008:administration & dosage*; D007155:Immunologic Factors / Q000008:administration & dosage*; D008027:Light; D011310:Preservatives, Pharmaceutical / Q000737:chemistry; D012542:Scattering, Radiation; D012965:Sodium Chloride / Q000737:chemistry; D013395:Sucrose / Q000737:chemistry
chemical_list: D002021:Buffers; D005079:Excipients; D007074:Immunoglobulin G; D007155:Immunologic Factors; D011310:Preservatives, Pharmaceutical; D012965:Sodium Chloride; D013395:Sucrose