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Hepatic Insufficiency Hepatically impaired patients (n= 8) had a 30% lower mean oral clearance of quetiapine than normal subjects. In two of the 8 hepatically impaired patients, AUC and Cmax were 3-times higher than those observed typically in healthy subjects. Since quetiapine is extensively metabolized by the liver, higher plasma levels are expected in the hepatically impaired population, and dosage adjustment may be needed (See DOSAGE AND ADMINISTRATION). Drug-Drug Interactions Text Continues Below
In vitro enzyme inhibition data suggest that quetiapine and 9 of its metabolites would have little inhibitory effect on in vivo metabolism mediated by cytochromes P450 1A2, 2C9, 2C19, 2D6 and 3A4. Quetiapine oral clearance is increased by the prototype cytochrome P450 3A4 inducer, phenytoin, and decreased by the prototype cytochrome P450 3A4 inhibitor, ketoconazole. Dose adjustment of quetiapine will be necessary if it is coadministered with phenytoin or ketoconazole (See Drug Interactions under PRECAUTIONS and DOSAGE AND ADMINISTRATION). Quetiapine oral clearance is not inhibited by the non-specific enzyme inhibitor, cimetidine. Quetiapine at doses of 750 mg/ day did not affect the single dose pharmacokinetics of antipyrine, lithium or lorazepam (See Drug Interactions under PRECAUTIONS). Clinical Efficacy Data The efficacy of SEROQUEL in the treatment of schizophrenia was established in 3 short-term (6-week) controlled trials of patients with schizophrenia who met DSM III-R criteria for schizophrenia. Although a single fixed dose haloperidol arm was included as a comparative treatment in one of the three trials, this single haloperidol dose group was inadequate to provide a reliable and valid comparison of SEROQUEL and haloperidol. Several instruments were used for assessing psychiatric signs and symptoms in these studies, among them the Brief Psychiatric Rating Scale (BPRS), a multi-item inventory of general psychopathology traditionally used to evaluate the effects of drug treatment in schizophrenia. The BPRS psychosis cluster (conceptual disorganization, hallucinatory behavior, suspiciousness, and unusual thought content) is considered a particularly useful subset for assessing actively psychotic schizophrenic patients. A second traditional assessment, the Clinical Global Impression (CGI), reflects the impression of a skilled observer, fully familiar with the manifestations of schizophrenia, about the overall clinical state of the patient. In addition, the Scale for Assessing Negative Symptoms (SANS), a more recently developed but less well evaluated scale, was employed for assessing negative symptoms. The results of the trials follow: Page: << Prev | 1 | 2 | 3 | 4 | Next >>
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