Help with mediation analysis

Hi,

I am new to the form. I have a dataset in which I am examining the effects of one (new) blood pressure treatment versus another (old) treatment in a clinical trial. I am using artery thickness as the outcome measure. We have also measured blood pressure at regular intervals through the trial.

Could someone suggest a way for me to measure the degree to which the effect of the drug on artery thickness is mediated through reduction in blood pressure, and not through another unmeasured mechanism?

I have examined the effects on artery thickness across tertiles of blood pressure, however I would like to quantify this.