title: Effect of cyclodextrins on the degradation rate of benzylpenicillin.
abstract: The effect of cyclodextrin (CD) inclusion complexes on the degradation of benzylpenicillin in aqueous solutions was investigated at several different pH values and 37°C. The effects of neutral as well as both positively and negatively charged CDs were evaluated; all together 13 different CDs. Kinetic studies with HPβCD and RMβCD at pH ranging from 1.2 to 9.6 showed that CDs have stabilizing effect on the β-lactam ring in aqueous acidic media but generally accelerated the hydrolytic cleavage of the β-lactam ring in neutral and basic media. At physiologic pH (pH 7.4) quaternary ammonium CD derivatives (i.e., positively charged CD derivatives) have the highest catalytic effect, resulting in 6- to 18-fold enhancement of hydrolysis rate, while both the neutral methylated CDs had much less effect, resulting in 2- to 3-fold enhancement, and the negatively charged CD derivatives, resulting in only about 1.1- to 1.2-fold enhancement in the hydrolytic cleavage of the β-lactam ring. Addition of water-soluble polymers to the aqueous reaction media containing CDs was shown to decrease the catalyzing effects of CDs on the β-lactam hydrolysis.
authors.forename: A
authors.initials: A
authors.lastname: Popielec
authors.forename: É
authors.initials: É
authors.lastname: Fenyvesi
authors.forename: K
authors.initials: K
authors.lastname: Yannakopoulou
authors.forename: T
authors.initials: T
authors.lastname: Loftsson
mesh_terms: D000073738:2-Hydroxypropyl-beta-cyclodextrin; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003505:Cyclodextrins / Q000737:chemistry*; D005079:Excipients; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008745:Methylation; D010400:Penicillin G / Q000737:chemistry*; D012996:Solutions; D047392:beta-Cyclodextrins
chemical_list: D000900:Anti-Bacterial Agents; D003505:Cyclodextrins; D005079:Excipients; D012996:Solutions; D047392:beta-Cyclodextrins; D000073738:2-Hydroxypropyl-beta-cyclodextrin; D010400:Penicillin G