Availability of active amphotericin B after filtration through membrane filters

The availability of active amphotericin B after filtration of the intravenous form of the drug through in-line filters was examined. Filtration through circular filters of 25-mm diameter and 0.45-micronm pore size resulted in little loss of active drug, although a marked decrease in flow occurred with time. Filtration through either circular or cylindrical filters with 0.22-micronm pores resulted both in significant losses of active drug and in marked decreases in flow. Thus, membrane filters of 0.22-micronm pore size are not suitable for use in intravenous administration of amphotericin B. The use of filters of 0.45-micronm pore size is appropriate only in situations in which decreased flow is acceptable.