- They are taking an anti-typhoid drug that is called as xyz.
- They are taking an anti-typhoid drug called xyz.
Which one is correct and why? or both are correct?
Assuming that "xyz" is the specific name of the drug, you can say either
They are taking an anti-typhoid drug (that is) called xyz.
or
They are taking an anti-typhoid drug (that is) known as xyz.
I put between parenthesis the words which you can easily omit.
Choice 2 is correct. '"called" here is a verb form meaning "named" or "known as". It is not normally used with an "as" in this sort of context. It is sometimes used with "as" when the meaning is "was selected to be". For example: "He was called as a priest in 1983." Even in that context "called to be" is far more commonly used. It could also be sued when "call" means to visit, or perhaps to telephone. For example "I called as a friend, not as a doctor."
So one could say:
President Carter was known as 'Jimmy' although is first name was James.
President Carter was called 'Jimmy' although is first name was James.
but "called as" would not work in such a sentence.