Senior assessor Swedish Medical Products Agency, Department of Drug Safety, Uppsala, Sweden Örsundsbro, Sweden
Background: In Sweden,14 percent of all women and 7 percent of all men were prescribed antidepressants in 2019, the most prescribed being selective serotonin reuptake inhibitors (SSRIs), for example sertraline and citalopram, followed by the alpha-2-antagonist mirtazapine, the serotonin and norepinephrine reuptake inhibitor (SNRI) venlafaxine, and the tricyclic antidepressant (TCA) amitriptyline. A well-known risk is that patients with mental health problems may use drugs for suicidal actions. Antidepressants can cause serious poisoning in case of overdose; the treatment can be demanding and there is a risk of death.
Objectives: To investigate antidepressants contributing to i) fatal intoxications and ii) consultation calls concerning severe acute poisoning, and their relationship to prescription of these drugs.
Methods: Antidepressants assessed by the forensic pathologist as contributing to at least 10 fatal intoxications in 2019 were included from the National Board of Forensic Medicine´s database. Number of consultation calls from hospitals about severe acute poisonings with antidepressants in 2019 was obtained from the Swedish Poison Information Center. Fatal intoxications and consultation calls were compared with number of individuals with at least one filled prescription for antidepressants in 2019 obtained from the Swedish Prescribed Drug Register.
Results: Antidepressants was assessed as contributing to fatal intoxication in 144 cases in 2019; the median age was 53 years and 92 cases (64 percent) involved women. Six antidepressants were assessed as contributing to at least 10 fatal intoxications; mirtazapine 34; venlafaxine 25; amitriptyline 24, citalopram 24; sertraline 18; and fluoxetine 11.
Venlafaxine was the antidepressant with the highest number of deaths in relation to prescriptions; 2.8 deaths/10,000 users. This was followed by amitriptyline (2.0/10,000); fluoxetine (1.8/10,000); citalopram (1.6/10,000); mirtazapine (1.5/10,000); and sertraline (0.6/10,000). Regarding calls to the poison information center, venlafaxine and amitriptyline were the antidepressants that had the highest number of calls about severe acute poisonings; venlafaxine 33 calls (3.6 calls/10,000 users), followed by amitriptyline 20 calls (1.7 calls/10,000 users).
Conclusions: Of the selected antidepressants, venlafaxine and amitriptyline had the highest number of deaths and consultation calls about severe acute poisonings relative to prescription. This can be explained by the fact that in Sweden, venlafaxine and amitriptyline is recommended for more severe depression, with a higher risk of suicide, compared to for example SSRIs. Also, venlafaxine and amitriptyline are considered more toxic in case of overdose compared to SSRIs.
