Global antipsychotic sales in 2010 were US$25.4 billion; of these, Seroquel (quetiapine) was the fifth highest selling pharmaceutical worldwide, costing an estimated US$6.8 billion. 4 In Canada, prescriptions for quetiapine rose by 300% between 2005 and 2012. Using the IMS Brogan Canadian CompuScript databases to identify prescribing data, researchers found that 50% of filled antipsychotic prescriptions in Canada were for quetiapine, and most came from family physicians.2 Although quetiapine is licensed for the treatment of schizophrenia and bipolar disorder and as an adjunctive to antidepressants in moderate to severe depression, much prescribing of quetiapine is offlabel.2,5 Off-label prescribing of antipsychotics has been studied extensively, including a meta-analysis of 170 studies.
6Leslie and colleagues 7 examined prescribing data from the US Department of Veteran Affairs and found that 60.2% of the 279 778 patients who received a prescription for an antipsychotic in 2007 had no indication for its licensed use; of these, 43% were prescribed quetiapine. More recently, researchers in the United Kingdom examined prescribing data using The Health Improvement Network, a primary care database of almost 10 million patients. 5 They found that only 36% (n = 4824) of those prescribed quetiapine had a serious mental illness recorded. Insomnia, anxiety and behavioural disturbance in elderly people and children are common reasons for off-label use. 3,6,8 Evidence of benefit for these indications is disputed. 6,9,10 Adverse metabolic, neurologic and cardiovascular effects 9,11 pose a significant risk of harm.11,12 Maglione and colleagues 6 calculated a number needed to harm of 8 (odds ratio 5.16, 95% confidence interval 2.93-9.51) for neurologic adverse effects in patients with dementia and of 16 (odds ratio 2.72, 95% confidence interval 2.07-3.56) for weight gain and increased appetite in other conditions. Background: Quetiapine is an antipsychotic that is widely prescribed off-label by family physicians despite evidence that safer alternatives exist. The aim of this research was to explore, in-depth, family physicians' reasons for this behaviour.