Really no interactions, although the bitters will cleanse the liver, which can lead to faster or more complete metabolism of some drugs. Therefore dosages may have to be adjusted.
I would be careful about trying to raise serotonin since the Effexor and Trazadone both block serotonin reuptake. You do not want excessive brain levels of serotonin.
I would focus primarily on tyrosine for dopamine and TMG for all the neurotransmitters, recommending 1,000mg each three times daily at least 30 minutes before meals. I recommend that she do this about 2 weeks before trying to wean off the medications to allow time for them to kick in.
Building up the flora is also a good idea. Kefir and either rice or oat bran for this.