How large were the groups? Was allocation of patients to groups at random? How were doses of A, B, and C determined? Wereo dose levels for A and for B similar between groups? Is the relationship between B dose and its effect on concentration of A linear?
What about a regression model with concentration of A as the dependent variable,
the adjusted doses of A and B as interval scaled predictors, and C as dummy-coded
predictor? Also the interactions should be included.
You could perform separate analyses for the different time points.If you want one
model which Includes all time points, then you will probably need multilevel
Maybe the correct to the such a question
would be that the op should contact the ethics
committee for the study, since letting amateurs
analyse real patient data might violate the
ethical approval of the study.