INTRODUCTION: New synthetic opioids (NSO), a class of new psychoactive substances (NPS), have recently emerged and pose an upcoming global public health challenge. The effects produced by NSO are similar to those from morphine, but they present greater pharmacological potency and abuse potential. Due to the increasing number of fatal overdoses and seizures in which NSO have been detected as heroin substitutes or adulterants, individuals with Opioid Use Disorder (OUD) represent a vulnerable population. The aim of our study was to describe and characterize from a gender perspective a Spanish cohort of potential conscious or unconscious NSO users.
METHODS: A cross-sectional study was conducted in a cohort of OUD participants under treatment in addiction care services in Barcelona and Badalona, Spain. Clinical evaluation was performed through an ad hoc survey, a scale to evaluate reasons to use an opioid without prescription (range 0-4) and the Wellbeing Index (WHO-5) (range 0-100). Objective consumption of NSO was assessed by urinalysis carried out by two validated methods: high-sensitivity gas chromatography-mass spectrometry (MS) and ultra-high-performance liquid chromatography-high-resolution MS.
RESULTS: A total of 154 participants with OUD were enrolled. They were mainly men (72.7%), mean age 47.8 years. Methadone was the predominant medication for opioid agonist treatment (mean dose 61.25 mg/day). A total of 32 (20.8%) participants reported having consumed some opioid to become "high" in the previous 3 months. The principal reasons for consuming illicit opioids were Replacing other drugs (mean 2.03) and Availability (mean 1.62), although Low price, was more highly valued by men (p = 0.045) and Shorter effect duration, most highly rated by women (p = <0.001). In the WHO-5, the mean score was 55 (SD = 30.1) without differences by gender. Fentanyl and derivatives or/and metabolites were detected in 7 (6.1%) participants, but illicit/non-prescribed NSOs were found in 5 out of 114 patients (4.4%), and other non-fentanyl opioids in 36 participants (26 men and 10 women).
CONCLUSION: A non-negligible consumption of NSO-fentanyl's (positive detection in 6.1% of biological samples) was detected. The reasons for using these substances and also the well-being differed between the genders. There is therefore both voluntary and involuntary NSO consumption in our country which highlights the importance of approaching this potential public health problem.