Clinical trial for crossover study by mixed model

[Xilong]

HI All,

I have a simple crossover clinical trial study which I need analysis. In brief, I had two groups: control group, and case group, and had two treatments: drug A and drug B. Each participant from each group was randomly picked to get treatment by drug A, then wash time, and drug B, or took drug B, then wash out, and drug A. during each treatment period, 5 data points for various variables were measured. My question was that how to compare the difference of time 5 (last time point) to time 1 (first time point) in drug A with difference of time 5 to time 1 in drug B in control group or case group? Second similar question was that how to compare the difference of time 5 to time 1 in drug A between control and case group? 

Any suggestions or sample codes will be appreciated.

Thanks in advance for your time.

Xilong Li