Faculty Bibliography

BACKGROUND: A substantial number of patients with psychosis receive quetiapine in amounts that are greater than what is recommended in the product labeling approved by drug regulatory agencies. The purpose of this article is to review the past and present dosing patterns of quetiapine for the treatment of schizophrenia. METHOD: A PubMed search for the period January 1, 1990, to July 1, 2005, was conducted to identify English-language articles related to quetiapine dose in schizophrenia using the search terms quetiapine, dose, and schizophrenia. Trends in dosing of quetiapine in a large, state-operated psychiatric hospital system and the anecdotal evidence describing the use of quetiapine in excess of 800 mg/day were also reviewed. RESULTS: The registration studies of quetiapine suggest a target dose range of 300 to 500 mg/day for schizophrenia. In contrast, among inpatients hospitalized in New York State in the period of April 1, 2004, to June 30, 2004, the mean dose of quetiapine prescribed was 620 mg/day, with 33.6% receiving doses in excess of 750 mg/day. Patients with nonwhite ethnicity, length of stay of at least 1 year, or history of prior state hospital admission were more likely to receive doses greater than 750 mg/day. Patients receiving quetiapine as antipsychotic monotherapy or in combination with other antipsychotics were equally likely to receive doses greater than 750 mg/day. Published anecdotal reports describe the use of quetiapine in excess of 800 mg/day and up to 2400 mg/day among patients not responding to lower doses, but currently there are no published reports from double-blind randomized clinical trials establishing the utility of this high-dose treatment strategy. CONCLUSIONS: Dosing of quetiapine in clinical practice is higher than what has been established in the registration program for schizophrenia. Although there is anecdotal evidence describing the use of quetiapine in excess of 800 mg/day, double-blind randomized clinical trials are needed

OBJECTIVE: This study examined data on patients with serious and persistent mental illness in a large state hospital system to determine whether patients who took second-generation antipsychotics were more likely to develop diabetes mellitus than patients who took first-generation antipsychotics. METHODS: A case-control study design was used. A new prescription of an antidiabetic medication was used to identify new cases of diabetes mellitus. Odds ratios were calculated for exposure to second-generation antipsychotics (clozapine, risperidone, olanzapine, quetiapine, and multiple second-generation antipsychotics) compared with exposure to first-generation antipsychotics. Cases and controls were identified by using a database that contained drug prescription information from the inpatient facilities that were operated by the New York State Office of Mental Health. Data from January 1, 2000, to December 31, 2002, were examined. Among 13,611 unique patients who received antipsychotics, 8,461 met entry criteria of being hospitalized for at least 60 days and not having an antidiabetic medication prescribed in the past. A total of 181 of these inpatients received prescriptions for an antidiabetic medication at least 30 days after their admission. Eight controls (N=1,448) for each case (N=181) were matched by calendar year, length of observation period, race, age group, and diagnosis, giving a total sample of 1,629 patients. RESULTS: Statistically significant elevations in risk were seen among patients who received more than one second-generation antipsychotic or clozapine or quetiapine, compared with patients who received first-generation antipsychotics alone. Although not statistically significant, odds ratios for olanzapine and risperidone were also elevated. Conditional logistic regression adjusting for gender and age did not change the results. CONCLUSIONS: Exposure to multiple second-generation antipsychotics or clozapine or quetiapine significantly increased the risk of treatment-emergent diabetes mellitus