title: Isomerization kinetics of panipenem in aqueous solution.
abstract: The isomerization kinetics of panipenem (INN: (+)-(5R,6S)-3-[(S)-1-(acetimidoylpyrrolidin-3-yl)thio]-6-[(R)-hydroxyethyl]-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid, CAS No. 87726-17-8) in aqueous solution were investigated. An equilibrium between the Z-form and E-form was observed, and it was found that the isomerization rates were affected by the pH of the solution. Under acidic conditions, the isomerization rates were small. However, the isomerization rates were increased with the pH value. This phenomenon resulted from the extent of proton dissociation from the acetimidoyl group.
authors.affiliation: Pharmaceutical Development Laboratories, Sankyo Co., Ltd., 1-12-1 Shinomiya, Kanagawa 254-0014, Japan. noitou@sankyo.co.jp
authors.forename: Nobuya
authors.initials: N
authors.lastname: Ito
authors.forename: Masahiko
authors.initials: M
authors.lastname: Suzuki
authors.forename: Akira
authors.initials: A
authors.lastname: Kusai
authors.forename: Kozo
authors.initials: K
authors.lastname: Takayama
mesh_terms: D008968:Molecular Conformation; D019999:Pharmaceutical Solutions; D013845:Thienamycins / Q000737:chemistry* / Q000493:pharmacokinetics*; D014867:Water / Q000737:chemistry
chemical_list: D019999:Pharmaceutical Solutions; D013845:Thienamycins; D014867:Water; C039536:panipenem