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Inhibitory effect of beta-cyclodextrin on ampicillin polymerization in aqueous solution
1Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Fukuoka University, Japan.
Drug Design and Delivery
|December 1, 1990
Summary
Ampicillin forms antigenic polymers in solution. Beta-cyclodextrin inhibits this polymerization through complex formation, preserving the beta-lactam ring structure.
Area of Science:
- Biochemistry
- Polymer Chemistry
- Pharmaceutical Sciences
Background:
- Ampicillin, a widely used antibiotic, can undergo polymerization in aqueous solutions.
- Understanding ampicillin polymerization is crucial for its stability and potential immunogenicity.
- The integrity of the beta-lactam ring is essential for ampicillin's antibacterial activity.
Purpose of the Study:
- To investigate the polymerization of ampicillin in aqueous solution.
- To characterize the resulting ampicillin polymers and their structural features.
- To explore the potential inhibitory effect of beta-cyclodextrin on ampicillin polymerization.
Main Methods:
- Anion-exchange chromatography for polymer separation.
- Fast atom bombardment mass spectrometry (FAB-MS) for polymer mass determination.
- Circular dichroism (CD) spectroscopy to assess beta-lactam ring integrity.
Main Results:
- Ampicillin polymerized into dimer, trimer, tetramer, and pentamer forms.
- The beta-lactam ring remained intact in all polymer forms, indicated by a positive Cotton effect.
- Beta-cyclodextrin inhibited ampicillin polymerization via equimolar complex formation, complete within 6 hours at 24°C.
Conclusions:
- Ampicillin polymerization yields antigenic polymers with intact beta-lactam rings.
- Beta-cyclodextrin effectively inhibits ampicillin polymerization through complexation.
- The study provides insights into ampicillin stability and potential interactions with cyclodextrins.