Benzos, stimulants commonly co-ingested with quetiapine


Seroquel tablets, 100mg and 25mg. Source: Luke-2/Wikimedia Commons.

Around one in 10 people in this group of Aussies used the antipsychotic medicine quetiapine for non-medical purposes

Among 7,000 people who injected drugs in Australia between 2011-2018, approximately one in 10 used the antipsychotic medicine quetiapine for non-medical purposes – i.e. in a way that was not prescribed, research led by the National Drug and Alcohol Research Centre (NDARC) at UNSW Sydney has found.

Quetiapine, often referred to by its originator brand Seroquel, is a used for the treatment of a range of psychotic disorders, including schizophrenia and bipolar disorder. However, low doses are also often used off-label for sleep and to manage anxiety.

The study, led by Dr Rachel Sutherland, found that approximately one in 10 participants reported past six-month use of prescribed quetiapine each year between 2011–2018 (9.2% in 2011 versus 9.7% in 2018).

The percentage of the sample reporting extra-medical quetiapine use was slightly higher than those reporting prescribed use, however, there was a small decline in rates of use from 2011 (15%) to 2018 (12%).

“This seems to have been largely driven by a decrease in Victoria, where non-medical quetiapine use reduced from 30% in 2011 to 15.3% in 2018,” said Dr Sutherland about the findings recently published in the journal Drug and Alcohol Dependence.

Extra-medical quetiapine use in all other jurisdictions has remained stable, except in the Northern Territory, which noted a small increase. The exact reason for the lower numbers in Victoria is unclear, said the authors.

“It is worth noting, however, that most of the studies documenting increased quetiapine-related harms in Australia have been conducted in Victoria, using local data sources,” they said.

“As such, it is possible that the trends observed in our paper may be due to a greater awareness of, and commitment to, reducing extra-medical quetiapine use and associated harms in Victoria compared to other Australian jurisdictions.”

Among those who reported extra-medical quetiapine use in 2018, swallowing was the most common route of administration (96% in 2018), with very few participants reporting injecting (5%), smoking (4%) or snorting (0%) as routes of administration.

There was very little overlap between prescribed and extra-medical quetiapine use, with less than 2% of participants reporting both prescribed and extra-medical use in each year from 2011 to 2018.

Despite the national decline in use over time, the report found past six-month use of benzodiazepines and stimulants was independently associated with non-medical quetiapine use in both 2011 and 2018.

“These findings are largely consistent with international studies that show benzodiazepines and stimulants are commonly co-ingested with quetiapine,” said Dr Sutherland.

“Although the exact motivations for people who injected drugs to use quetiapine non-medically remains uncertain, it seems plausible that quetiapine, as well as drugs like benzodiazepines, are being used to ‘come down’ from stimulants.”

Past six-month use of new psychoactive substances (NPS) was also correlated with extra-medical quetiapine use in 2018.

Researchers have previously raised concerns that reliance on quetiapine to counteract “bad trips” may make consumers overly confident in their ability to manage the adverse effects of NPS, the authors pointed out.

“Overall, these findings highlight that we need to target harm-reduction interventions focused on polysubstance use to reduce potential risks in this group,” said Dr Sutherland.

The survey on which the study was based specifically asks about use of Seroquel, the originator brand of quetiapine in Australia and the brand most commonly referred to in the population of people who injected drugs, the authors noted.

Therefore the study findings may not be generalisable to generic brands of quetiapine that are now available for use.

Read the full study here

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