In vitro and in vivo comparisons of amphotericin B and N-D-ornithyl amphotericin B methyl ester.

N-D-Ornithyl amphotericin B methyl ester (N-D-ornithyl AmE) has a lower toxicity for animals than does amphotericin B (AmB), and peak serum levels can be achieved that are fourfold higher than those obtained with an equivalent dose of AmB. However, N-D-ornithyl AmE has one-fourth the in vitro activity and between one-fifth and one-eighth the in vivo activity of AmB. N-D-ornithyl AmE and the corresponding lysyl derivative also lack the immunoadjuvant effects of AmB.