Trends in tricyclic antidepressant prescribing and poisoning in England and Wales 2016-2020

Tricyclic antidepressants (TCAs) are commonly prescribed despite no longer being a NICE-recommended first-line treatment for depression and their recognized toxicity in overdose. This study examined prescribing, mortality, hospital admissions and clinical TCA data to quantify the use and impact of TCAs in England and Wales.

Primary care prescription data for the eight TCAs currently licensed in England and Wales were analysed alongside hospital admission and mortality data relating to TCAs over the study period (January 2016-December 2020 inclusive). Monthly Toxbase™ accesses regarding TCAs during the study period for each TCA were quantified. National Poisons Information Service (NPIS) enquiry data involving TCA exposure were obtained and patient demographics, circumstance, dose ingested and poisoning severity were analysed.

English and Welsh mean monthly TCA prescriptions per 100 000 people significantly increased during the study period, both driven by amitriptyline 10 mg tablets (95% confidence interval [CI] 3.49-4.59 and 6.36-7.92, respectively). Deaths from poisoning where a TCA was mentioned on the death certificate fell. Toxbase™ accesses increased for amitriptyline and nortriptyline but decreased for all other TCAs. NPIS telephone enquiries relating to TCAs decreased. Hospital admission data did not demonstrate an increase in admissions related to TCAs.

Reduced TCA poisoning mortality in England and Wales was seen despite increased dispensing of TCAs in both nations. The prescribing of low-dose amitriptyline formulations was associated with increased consultation with Toxbase™ but not increased hospital admissions or NPIS enquiries, suggesting a fall in TCA poisoning severity resulting from their changing pattern of usage.