Tissue culture experiments indicate that approximately one-third of human breast cancers are prolactin dependent in vitro, a factor of potential importance if the prescription of these drugs is considered in a patient with previously detected breast cancer. As is common with compounds which increase prolactin release, mammary gland, and pancreatic islet cell neoplasia (mammary adenocarcinomas, pituitary and pancreatic adenomas) was observed in carcinogenicity studies conducted in mice and rats. Neither clinical studies nor epidemiologic studies conducted to date have shown an association between chronic administration of this class of drugs and tumorigenesis in humans, but the available evidence is too limited to be conclusive [see Carcinogenesis, Mutagenesis, Impairment of Fertility (13.1)].

5.15 Transaminase Elevations
Asymptomatic, transient and reversible elevations in serum transaminases (primarily ALT) have been reported. The proportions of patients with transaminase elevations of >3 times the upper limits of the normal reference range in a pool of placebo-controlled trials ranged between 1% and 2% for SEROQUEL XR compared to 2% for placebo. In schizophrenia trials in adults, the proportions of patients with transaminase elevations of >3 times the upper limits of the normal reference range in a pool of 3- to 6-week placebo-controlled trials were approximately 6% (29/483) for SEROQUEL compared to 1% (3/194) for placebo. These hepatic enzyme elevations usually occurred within the first 3 weeks of drug treatment and promptly returned to pre-study levels with ongoing treatment with quetiapine.

5.16 Potential for Cognitive and Motor Impairment
Somnolence was a commonly reported adverse event reported in patients treated with quetiapine especially during the 3-day period of initial dose titration. In schizophrenia trials, somnolence was reported in 24.7% (235/951) of patients on SEROQUEL XR compared to 10.3% (33/319) of placebo patients. In a bipolar depression clinical trial, somnolence was reported in 51.8% (71/137) of patients on SEROQUEL XR compared to 12.9% (18/140) of placebo patients. In a clinical trial for bipolar mania, somnolence was reported in 50.3% (76/151) of patients on SEROQUEL XR compared to 11.9% (19/160) of placebo patients. Since quetiapine has the potential to impair judgment, thinking, or motor skills, patients should be cautioned about performing activities requiring mental alertness, such as operating a motor vehicle (including automobiles) or operating hazardous machinery until they are reasonably certain that quetiapine therapy does not affect them adversely. Somnolence may lead to falls.

 In short-term adjunctive therapy trials for MDD, somnolence was reported in 40% (252/627) of patients on SEROQUEL XR respectively compared to 9% (27/309) of placebo patients. Somnolence was dose-related in these trials (37% (117/315) and 43% (135/312) for the 150 mg and 300 mg groups, respectively).

5.17 Priapism
One case of priapism in a patient receiving quetiapine was reported prior to market introduction. While a causal relationship to use of quetiapine has not been established, other drugs with α-adrenergic blocking effects have been reported to induce priapism, and it is possible that quetiapine may share this capacity. Severe priapism may require surgical intervention.

5.18 Body Temperature Regul