The objective of this study was to prove the bioequivalence of Roxane Laboratories' Quetiapine Fumarate 300 mg Tablet under fasted steady state conditions.

Inclusion Criteria:

1. Stable patients with the DSM-IV TR diagnosis of schizophrenia. These patients are to be identified via psychiatric evaluation and meet DSM-IV TR criteria for schizophrenia of paranoid (295.30), disorganized (295.10), catatonic (295.20), undifferentiated (295.90), or residual (295.60) subtype.
2. Patient to have no significant breakthrough symptoms or exacerbations of psychiatric illness necessitating hospitalization in the 3 months prior to screening.
3. Patient to have a CGI-S score of 3 or less at screening.
4. On a stable regimen of treatment to include quetiapine fumarate for 3 months minimum prior to screening, and on a dose of quetiapine fumarate totaling 600 mg total per day for a minimum of 1 month prior to screening. Patients who are on qd dosing of daily quetiapine fumarate must be willing to convert to 300 mg bid dosing for the duration of the study.

Exclusion Criteria:

1. All other DSM-IV axis I diagnoses, including schizoaffective disorder, schizophreniform disorder and/or any other psychiatric diagnoses that in the opinion of the principal investigator may during the conduct of the trial become a primary treatment concern, or may interfere in the patients ability to participate in the trial.
2. Positive test for HIV, Hepatitis B, or Hepatitis C.
3. Treatment with known enzyme altering drugs.
4. History of allergic or adverse response to quetiapine or any comparable or similar product.