Occurrence and time course of NPS benzodiazepines in Sweden - results from intoxication cases in the STRIDA project

Clin Toxicol (Phila). 2019 Mar;57(3):203-212. doi: 10.1080/15563650.2018.1506130. Epub 2018 Oct 22.


Context: In recent years, many unclassified benzodiazepines (BZD) have appeared through online sale as new psychoactive substances (NPS). This study describes bioanalytical and clinical data related to intoxications involving NPS BZD ("designer BZD") in the Swedish STRIDA project.

Study design: Case series of consecutive patients with admitted or suspected intake of NPS presenting to hospitals all over Sweden for emergency treatment in 2012-2016.

Patients and method: Urine samples collected in the STRIDA project were analyzed for 28 NPS BZD, using immunoassay and liquid chromatography-high-resolution mass spectrometry . Data of patient's age, gender, reported substance exposure, clinical signs, and treatment were obtained from medical and Poisons Information Center (PIC) records.

Results: A total of fifteen different NPS BZD were analytically confirmed in 217 of 1913 (11%) cases involving patients (81% men) aged 15-66 (mean 28) years. The frequency of positive samples increased from 4% in 2012 to 19% in 2015. Etizolam (20 cases) was the first detected NPS BZD (January 2012), and it was followed by metizolam (four cases), estazolam (two), pyrazolam (33), flubromazepam (33), nifoxipam (five), diclazepam (four), meclonazepam (26), bromazepam (one), flubromazolam (92), deschloroetizolam (one), clonazolam (16), 3-hydroxyphenazepam (eight), ketazolam (one), and phenazepam (one). Most cases (89%) also involved other drugs. Use of NPS BZD was rarely (15%) reported during PIC consultation. In 24 patients exposed only to NPS BZD, CNS depression was the most prominent clinical sign, seven were observed in the intensive care unit, and they responded positively to flumazenil treatment.

Conclusions: An increasing use of NPS BZD in Sweden was detected in acute intoxication cases, sometimes leading to intensive care monitoring and support needs.

Keywords: Designer benzodiazepines; intoxications; liquid chromatography–mass spectrometry; new psychoactive substances.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Benzodiazepines / poisoning*
  • Benzodiazepines / urine
  • Chromatography, High Pressure Liquid
  • Designer Drugs / poisoning*
  • Emergency Medical Services
  • Female
  • Flumazenil / therapeutic use
  • GABA Modulators / therapeutic use
  • Humans
  • Male
  • Mass Spectrometry
  • Middle Aged
  • Substance-Related Disorders / complications
  • Substance-Related Disorders / epidemiology
  • Sweden / epidemiology
  • Young Adult


  • Designer Drugs
  • GABA Modulators
  • Benzodiazepines
  • Flumazenil