title: The effect of cyclodextrins on chemical and physical stability of glucagon and characterization of glucagon/gamma-CD inclusion complexes.
abstract: The purpose of the study was to evaluate the effect of cyclodextrin (CD) complexation on the chemical and physical stability of a polypeptide hormone glucagon and to study the interactions between glucagon and gamma-cyclodextrin molecules in inclusion complexes. The chemical stability of glucagon at pH 2.0 was studied with HPLC-UV and HPLC-MS/MS. The physical stability of glucagon at pH 2.5 was studied by measuring the turbidity (A(405 nm)) and viscosity (Ostwald capillary viscosimeter) of the samples. The structure of glucagon/gamma-CD complexes at pH 2.5 was studied with 2D-NMR. The presence of various CDs increased the chemical half-life of glucagon at pH 2.0 (37 degrees C, 0.01 M HCl, ionic strength 0.15) and prolonged the lag-time before aggregation at pH 2.5 (0.9% (w/v) NaCl in 3.2 mM HCl). The NMR studies showed that the side chains of all the aromatic amino acid residues (Phe6, Tyr10, Tyr13, Phe22, Trp25) and leucines (Leu14 and Leu26) of glucagon interacted with the cavities of the gamma-CD molecules. The present study shows that glucagon forms inclusion complexes with cyclodextrins in acidic solution, resulting in an improvement in its chemical and physical stability.
authors.affiliation: Department of Pharmaceutical Chemistry, University of Kuopio, PO Box 1627, FIN-70211 Kuopio, Finland. laura.matilainen@uku.fi
authors.forename: Laura
authors.initials: L
authors.lastname: Matilainen
authors.forename: Kim Lambertsen
authors.initials: KL
authors.lastname: Larsen
authors.forename: Reinhard
authors.initials: R
authors.lastname: Wimmer
authors.forename: Pekka
authors.initials: P
authors.lastname: Keski-Rahkonen
authors.forename: Seppo
authors.initials: S
authors.lastname: Auriola
authors.forename: Tomi
authors.initials: T
authors.lastname: Järvinen
authors.forename: Pekka
authors.initials: P
authors.lastname: Jarho
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D005079:Excipients / Q000737:chemistry*; D005934:Glucagon / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D014783:Viscosity; D047408:gamma-Cyclodextrins / Q000737:chemistry*
chemical_list: D005079:Excipients; D047408:gamma-Cyclodextrins; D005934:Glucagon