David M. Pache

Antidepressant use is common in women. However, characteristics associated with duration of use remain unclear. We conducted a descriptive study using data from the 1973-1978 and 1946-1951 birth cohorts of the Australian Longitudinal Study on Women’s Health linked to antidepressant dispensing records from the Pharmaceutical Benefits Scheme, July 2012 to December 2019 to examine use patterns and their associated characteristics. Early discontinuation and prolonged antidepressant use were common, a significant deviation from current guideline recommendations. There were 5553 episodes of antidepressant use in 4416 women, with a mean estimated duration of first-time use of 664 days. One in four women had only one prescription filled, while 32% continued treatment beyond two years, with 14% continuing use at five years. Age and previous antidepressant use impacted duration of use, with a shorter average duration of use and a higher proportion of discontinuation for each subsequent episode after the first prescription.

Introduction: Antidepressant use has increased over the last two decades, with Australia and New Zealand among the highest antidepressant users in Organisation for Economic Co-operation and Development (OECD) countries. Comorbidity and polypharmacy are common in antidepressant users, increasing the likelihood of interaction-related adverse drug events, which are frequently preventable. Aim: We aimed to identify, profile, and analyse potential antidepressant drug–drug interactions in information-seeking antidepressant users. Methods: We retrospectively analysed antidepressant-related drug–drug interaction enquiries from patients or carers who contacted a pharmacist-led Australian national medicines call centre over an 8-year period to determine patient characteristics, concomitant drugs involved, prevalence and type of antidepressant-related drug–drug interaction across life stages, and associated risks. Results: Of 3899 antidepressant drug–drug interaction calls, the most frequent concomitant drugs were antipsychotics, opioids, benzodiazepines, and complementary medicines. Narrative analyses of 2011 calls identified 81.0% of patients with potential drug–drug interactions and 10.4% categorised with worrying symptoms. The most frequent drug–drug interaction risks were excessive sedation, increased anticholinergic effects, serotonin syndrome, and suicidal thoughts. Carers of children aged <15 years and older adults (65–74 years) were more likely to report experiencing worrying symptoms. Although more potential pharmacodynamic than pharmacokinetic interactions were recorded, pharmacokinetic interactions tended to have more significant clinical impact. Discussion: Antidepressant users often have information gaps and safety concerns regarding drug–drug interactions that motivate help-seeking behaviour. Symptoms and drug–drug interaction consequences may be underestimated in these patients. Primary care health professionals have a role in proactively addressing the risk of drug–drug interactions to support benefit-risk assessment and shared decision-making.