Drug A is administered concurrently with or sequentially to Drug B.

I want to say in a formal manner that Drug A and Drug B are administered either at the same time or at different times, but I don’t want to say whether A or B comes first.

Two questions:

  1. What is the correct preposition after “sequentially”? “To”? “With”?
  2. If drug A is administered sequentially to Drug B, does that mean that Drug B is administered after drug A? If so, how can this be expressed without limiting the order.
  • 5
    Drugs A and B are administered either concurrently or sequentially. – Jim Jul 8 '14 at 5:16
  • Yes, if it doesn't matter in which order you take them then @Jim's phrasing seems best to me. I think if you say A is administered sequentially to B it tends to suggest that B is taken first and then A. – WS2 Jul 8 '14 at 6:38

Confusingly, if you say

"A and B are administered sequentially"

It DOES NOT necessarily mean A THEN B. It just means the listed items in that set are sequential, not concurrent.

You should say "A and B are administered sequentially, with A before B."

The other is "A and B are administered concurrently."

(It's very surprising you don't know this if in the industry! You're going to kill patients.)

If you are trying to express both of these facts...

Fact 1: "A and B are administered sequentially"

Fact 2: "A before B."

... in the same sentence.

In my opinion you can not do that properly. "B must be given sequentially after A" is crap. "Sequential" is a descriptor of a set of items; so it should be separate.


Do you not want to say which drug is given first a) because you don't know, b) because it doesn't matter, or c) because it's a test question that you want the reader to answer?

If a) you don't know, why are you saying it at all?

If b) it doesn't matter, just say so: "A and B can be given either simultaneously or in sequence; the order in which they are given is unimportant."

If it's c) a test question, frame it that way: "If A and B are not given concurrently, what is the correct sequence?"

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