23 September 2019

Xanax limits fail to curb heavy usage

Drugs Mental Health PBS

Subsidy restrictions on alprazolam (Xanax) do not seem to have reduced overuse of the anti-anxiety drug, according to a study of PBS data and calls to a poisons information service.

In early 2017 the Pharmaceutical Benefits Scheme made three changes, delisting the 2mg tablet from subsidy, reducing the pack size from 50 to 10 tablets, and eliminating repeats.

RANZCP guidelines say benzodiazepines should only be used short term as anxiolytics because of adverse effects such cognitive impairment, falls and sedation, and the risk of dependency.

They also cause more fatal overdoses than any other drug class.

The lower-dose tablets still on the PBS are all designated “authority required” as last-line treatments; approval for larger pack sizes can be sought along with authority to prescribe.

The study, led by University of NSW biostatistician Dr Andrea Schaffer and published in JAMA Network Open last week, sampled PBS data and found that overall dispensings under the subsidy scheme more than halved, as did the number of patients being dispensed.

However, there was little change in the volume of drug dispensed each time, and the proportion of dispensings of more than 100 tablets quadrupled. There was no change in the number of alprazolam-related calls to the NSW Poisons Information Centre, nor in the proportion of calls involving 2mg tablets.

That suggests many users are bypassing the PBS and paying the full cost of alprazolam, which is under $20 for 10 x 2mg tablets, and therefore weren’t captured by the data.

Dr Schaffer, an NHMRC Early Career Research Fellow at the University of NSW’s Centre for Big Data Research in Health, said the price of the drug was too low for the withdrawal of subsidy to have an effect.

“Alprazolam is a very cheap medicine,” she told The Medical Republic. “So for most people that probably isn’t a huge disincentive to go to the private market.

“We looked at poisoning calls and those didn’t change very much, and the people who were having poisoning events were using a 2mg tablet still. So we suspect that it is still circulating in the community, although there aren’t any very good data on that in Australia. 

“The thing is benzodiazepines are very hard medicines to discontinue if you’ve been taking them a long time, and I think this shows that suddenly restricting access isn’t going to help people.

“One of the messages here is that there aren’t a lot of good interventions out there to reduce use of these medicines, so thinking very carefully before you initiate them is a good idea.”

Dr Lisa Lampe, associate professor of psychiatry at Newcastle University, co-authored the RANZCP guidelines on the treatment of panic disorder, social anxiety disorder and generalised anxiety disorder.

She told The Medical Republic it was disappointing that new patients were still being initiated on alprazolam, when there were alternatives less likely to lead to psychological and physiological dependence.

“I was initially surprised that rates of prescribing higher tablet number packs had increased, but on reflection it’s not so surprising as prescribers try to save their patients some money – this may well explain prescription of higher tablet strength as well,” she said.

“However, it’s not all bad news as it looks like the number of people receiving scripts for alprazolam has about halved. It would be useful to know the clinical rationale behind these prescriptions, but unfortunately the data don’t tell us.”

Dr Schaffer said it was possible that the current cohort of heavy users would continue, since the restrictions were easy to get around, but that they would inhibit prescribers from initiating new patients.

She said there had been a substantial drop in casual use of alprazolam when it was made a Schedule 8 drug in 2014. Members of PBAC involved in that decision had told her they expected the main difference would be to new rather than existing users.

Dr Schaffer said the study did not capture reasons for prescribing alprazolam and that some patients did receive a benefit.

JAMA Network Open, 19 September