psych meds question

We have a new hemodialysis patient who has been on alprazolam 0.125mg po am, 0.25mg po hs, olanzapine 10mg po hs, and venlafaxine ER 150mg po hs for "years" for an undisclosed psychiatric disorder.
About halfway through the run, this patient has become almost nonresponsive .. no significant changes in BP. We were consulted by the nephrologist to see if this is medication related. None of these medications are dialyzed out and are given at bedtime anyway (other than the am dose of alprazolam) but we are perplexed. Any experiences with psych meds causing issues on dialysis? I personally think there is something else going on independent of dialysis but I wanted to cover my bases. Thanks in advance.