-American Psysiological Society

04/20/2008 - “Based on these findings we concluded that male rats treated with olanzapine experienced an early disruption of energy metabolism.  

In the study 18 male rats were randomly assigned to one of three groups: (1) those receiving the conventional antipsychotic drug haloperidol (HA); (2) those receiving the atypical antipsychotic drug olanzapine (OL); or (3) the control (CO) group which did not receive either drug.  

The medicines were given in food for a period of six weeks. Female rats were excluded to eliminate bias in the study since antipsychotic-induced weight gain in female rodents is likely related to an interaction of the drugs with estrogens.  

Testing after four weeks found that the concentration of blood sugar (as glucose) was higher in OL rats (0.87 g/l) than in CO rats (0.75 g/l) and the levels increased more rapidly after a glucose meal. Testing six weeks later found fasting blood sugar levels continued to rise in OL rats (1.46 g/l vs. 1.25 g/l in CO rats) while the level of lipids (fats) in the blood was similar for both groups. Although there was no difference in body weight gain or food intake, the proportion of fat stored in the abdominal cavity was higher in OL rats (1.63%) vs. CO rats (1.44%).  

The HA rats did not vary in any way with the control group at any time. They exhibited a lower blood sugar level after a glucose meal and a lower proportion of intraabdominal fat store (1.44%) than OL rats. Senior study author Dominique Hermier said, “Based on these findings we concluded that male rats treated with olanzapine (Zyprexa) experienced an early disruption of energy metabolism.

This was a result of the fat tissue we observed and the impairment in blood sugar regulation which are both associated with metabolic syndrome and subsequent risk of diabetes.”