Hi

I'm rather new to statistical analysis and I'm currently doing medical research for the first time.
I would really appreciate your inputs as to which analysis would be good for my study.

Patients were divided in to 2 groups.
One group were treated with 3 drugs, A, B and C. The other only with A and B.
The concentrations of A and B were measured.
We know that the concentration of B has an impact on the concentration of A.

1) I want to examine whether C has an effect on the concentration of A, when corrected for the concentration of B and the dosage given of A.

2) If it does have an effect, as I suspect, I want to examine what effect the dose of C has on A. If the higher doses of C has a larger effect on the concetration of A.

I hope you can help.
Thanks in advance!