[Chemical and microbiological aspects of the quantitative analysis of amphotericin B]

Amphotericin B can be determined by chemical (HPLC, spectrophotometry) and microbiological (bioassay) methods. The utilization of both during a stability test can give more detailed information about the activity and concentration change of amphotericin B solutions. Previously published HPLC methods do not lay stress on the separation of by-constituents present in the substance. We have also observed that the bioassay conditions described in the Ph. Eur. 6. are not suitable for the measurement of concentration change experienced during a stability test. The aim of our study was to optimize the chemical and microbiological methods. We have improved the eluent system based on earlier HPLC methods for the separation of the main heptaene and the minor tetraene by-constituents in Fungizone (Bristol-Myers Squibb). The most optimal bioassay conditions were determined where a relatively wide concentration range can be measured. With the improved methods both chemical and microbiological changes can be more accurately measured in our future stability tests.