A few studies have shown that orally disintegrating Zyprexa Zydis appears to cause less weight gain than standard Zyprexa, but they have been short term stud- ies. This one-year study (which did not receive any industry funding) enrolled 26 patients, all of whom had schizophrenia or schizoaffective disorder, and all of whom had been stabilized on standard Zyprexa (average dose 13.9 mg/day). These patients ranged from overweight to obese, with an average BMI of 32.4, and an average weight of 96.2 kg (212 pounds). In this open trial, patients were switched to the equivalent dose of Zyprexa Zydis. Of the 22 patients who completed the trial, 82% lost weight, and the average weight loss at one year was 2.7 kg (5.9 pounds). Most of the weight loss occurred within the first three months (Chawl B and Luxton-Andrew H, Hum Psychopharmacol Clin Exp 2008;23:211-216).

TCPR’s Take: Because this was an open trial, some of this weight loss may have been due to the effects of expectancy rather than the effect of the change in formulation per se. Nonetheless, this represents the fifth study consistent with the theory that Zyprexa Zydis causes less weight gain than standard Zyprexa. Since Zydis disintegrates on contact with the tongue, much of it is absorbed in the blood- stream before reaching the stomach. If the Zyprexa causes weight gain by stimulat- ing serotonin receptors in the stomach, Zydis may decrease weight gain by avoid- ing this hypothetical mechanism of action.