# How to use mixed ANOVA with 2 between-subjects and 1 within-subjects design

I know mixed ANOVA should be used when testing a data set containing within-between subjects design. As my data structure shows below, my between-subjects factor is Age group, each group takes Pill A and Placebo at different time points (within-subjects). But the tricky thing is that within Placebo, there is a between-subjects factor by placebo size; some people take Large Placebo, others take Small Placebo. How can I count this in my mixed ANOVA analysis?

The effect I intend to test is the Age x Pill interaction effect. My ultimate question is how different age groups react differently to Pill A?

Also, what is the equivalent OLS for this mixed ANOVA? Hierarchical Linear Model?

Thanks!