I know this is an old post, but I would like to share with Karl our experiences with Clozaril. My son tried different anti-psychotics without success. We were told that clozaril is the "gold standard" for psychosis, and it was finally prescribed during a hospitalization. We felt crushed and hopeless when his white blood count and neutrophils dropped into the danger zone after only a week.
A year later, after being on Zyprexa and Prozac and 8 ECT treatments, he was hospitalized again. I convinced the doctor to try lithium. We knew someone with severe treatment resistant depression who had remarkable success with this drug. A nurse practitioner told us that it also helps psychosis though it is not prescribed much in USA for that. We went to 2 psychiatrists who refused to prescribe lithium. It has completely balanced his moods (no surprise), but it also has helped with paranoia, practically stopped the "mean" voices, and reduced voices overall. He used to take 36 mg. of Zyprexa and 50 mg. of Prozac. He has over time reduced to 27 1/2 mg. of Zyprexa and 30 mg. of Prozac.
I can't fully describe the difference lithium has made, but I would urge everyone who is dissatisfied with their current meds to give it consideration.