Advancing toxicovigilance of recreational drugs, including new psychoactive substances, by using data from four European poison centres

Introduction: Common recreational drugs and new psychoactive substances pose challenges to public health. This study investigated the feasibility of merging cases of recreational drug poisoning reported to European poison centres.

Methods: Four European poison centres (Freiburg, Germany; the Netherlands; Sweden and Switzerland) collaborated in a retrospective, observational study. We collected aggregated data on poisonings with 11 common recreational drugs and case-by-case data on poisonings with new psychoactive substances in 2021 by using anonymized data from electronic case reports.

Results: In 2021, 2.0% of the poison centre calls involved poisonings with recreational drugs. The poison centres were contacted about 3,705 patients, involving 4,380 drug exposures, of which 3,708 were common recreational drugs, and 672 were new psychoactive substances. Per million inhabitants, the poisoning rate with common recreational drugs varied between 48 (Freiburg) and 145 (Sweden). Poisonings with amfetamine (22%), cocaine (20%), all delta-9-tetra-hydrocannabinol-containing preparations (20%), and 3,4-methylenedioxymetamfetamine (13%) exposures were most frequent. The poisoning rate per million inhabitants with new psychoactive substances varied between two (Switzerland) and 29 (Netherlands). Cathinones (43%), designer benzodiazepines (28%), and phenethylamines (13%) were the most commonly involved new psychoactive substance classes. Symptoms following cathinone poisoning were tachycardia (35%) and hypertension (13%), while following designer benzodiazepines, somnolence was most prominent (38%). The majority of users of new psychoactive substances were male (67%), 55% were between 18 and 30 years, and 8% involved minors (<18 years).

Discussion: This study showed the feasibility of merging data on recreational drug poisoning collected by poison centres in four countries. Despite underestimating the overall incidence of drug-related health incidents, poison centre data offers national coverage, unlike other data sources, such as drug-related emergency department visits.

Conclusion: This multi-centre, multi-national study reported a substantial annual number of recreational drug poisonings, with a variable proportion of new psychoactive substances. It shows that poison centre data offers detailed insights into exposures to common recreational drugs and new psychoactive substances, user characteristics, and symptoms. It can be used for comprehensive monitoring of drug-related health incidents on a multi-national level.