ampicillin | Acta Medica Marisiensis

Background: Ampicillin in trihydrate form is a b-lactamine antibiotic frequently used in therapy as suspensions and capsules. Because of the low stability only dry suspensions are sold, and also the low stability in acidic environment is source of unwanted side effects and bioavailability variations.
Aim: Our goal was to stabilize ampicillin so that a better stability can be obtained both in water suspensions and acidic solutions. This way misuse due to faulty preparation, side effects and bioavailability problems can be avoided.
Methods: In order to assess the changes in the ampicillin concentration high performance liquid chromatography (HPLC) and thin layer chromatography (TLC) methods have been used.
Results: None of the tried excipients improved stability of ampicillin suspensions. In contrast cyclodextrins and magnesium salts of glutamic and aspartic acid greatly improved the stability of ampicillin acidic solutions. In high amounts cyclodextrins also change the decomposition kinetic of ampicillin, which is usually a first order kinetic process.
Conclusions: Cyclodextrins and magnesium salts of glutamic and aspartic acid have the potential to be used in ampicillin containing formulations in order to increase its stability, bioavailability and to reduce adverse effects.

Introduction: The objective of this paper is the development and optimization of a capillary electrophoresis method, which allows the separation of four frequently used penicillin derivatives (amoxicillin, ampicillin, benzilpenicillin and oxacillin), with possible application in the analysis of environmental samples.
Material and method: In our experiments we worked on water solutions of the studied penicillins. The analysis was performed on an Agilent Capillary Electrophoresis System with a diode array detector. The data were recorded and processed by Chemstation software.
Results: Different buffer solutions were tried out in order to reach the most efficient separation of the studied compounds. The influence of different analytical parameters was evaluated by varying the buffer concentration, buffer pH, voltage, temperature, injection time and pressure. The analytical performance of the method was verified, in order to estimate reproducibility and sensitivity.
Conclusions: A micellar electrokinetic capillary chromatography method has been developed for the separation of the four penicillins. We obtained the best results with a buffer solution containing 25 mM sodium tetraborate and 100 mM sodium dodecyl sulfate (pH = 9.3), the separation being achieved in approximately 5 minutes.