你说的base是碱式,那colistin base翻译成中文该怎么说,写文章用的,请你再给我讲讲,就比如这句,Colistimethate sodium manufactured by AXELLIA is prescribed in international units,but colistimethate sodium manufactured by Parkdale Pharmaceutical is prescribed in milligrams of colistin base.请帮我一下,非常感谢。我对这个概念理解的很模糊。