title: Stabilization of a polypeptide in non-aqueous solvents.
abstract: A pituitary adenylate cyclase-activating peptide (PACAP) analogue (HSDAVFTDNYTRLRKQVAAKKYLQSIKNKRY, P66) was formulated in several non-aqueous solvents in anticipation of improved shelf-life stability. However, the stability of this peptide in these solvents was found to be as poor as in an aqueous solution. The major degradation reaction in non-aqueous solvents was dimer formation. The proposed mechanism for dimerization was a nucleophilic attack of a basic amino acid on cyclic imide formed by dehydration or deamidation of Asp or Asn. Two approaches were found to be effective in stabilizing the peptide in non-aqueous solvents: (1) acidification of the peptide and (2) use of zinc chloride in the formulation. Stabilization could be attributed to reduction of the nucleophilicity of the reactive groups through protonation and metal-peptide interaction through chelation. The stabilization approaches are applicable only in a non-aqueous environment for this peptide, and possibly for other peptides with similar reactive moieties.
authors.affiliation: Bayer HealthCare, 800 Dwight Way, Berkeley, CA 94701, United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Sheryl
authors.initials: S
authors.lastname: Martin-Moe
authors.forename: Clark
authors.initials: C
authors.lastname: Pan
authors.forename: Laszlo
authors.initials: L
authors.lastname: Musza
authors.forename: Y John
authors.initials: YJ
authors.lastname: Wang
mesh_terms: D002712:Chlorides / Q000737:chemistry; D019281:Dimerization; D004355:Drug Stability; D004356:Drug Storage; D006863:Hydrogen-Ion Concentration; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry
chemical_list: D002712:Chlorides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012997:Solvents; D017967:Zinc Compounds; C529639:p66 - pituitary adenylate cyclase-activating peptide analog; C016837:zinc chloride