What Happened to Amphotericin A

Question:

Everyone knows about amphotericin B and the potential side effects. But what happened to amphotericin A?

Answer:

Amphotericin A didn’t have useful antifungal activity, so during the original manufacturing process of amphotericin B the goal was solely to reduce the amount of amphotericin A below 15{64e6c1a1710838655cc965f0e1ea13052e867597ac43370498029d1bc5831201} (much lower now).  Toxicity was not improved with reductions in amphotericin A so its unlikely to significant contribute to toxicity either.