Use patterns of classic, novel, and herbal opioids

Background: Data on use patterns and psychological and physical effects of novel synthetic opioids (NSOs) and herbal opioids like kratom (Mitragyna speciosa) lags behind that of classic opioids. Aims: This study aimed to describe use patterns, adverse events, subjective experience and motivation of use with classic, novel and herbal opioids. Methods: A two-part survey was used. The first part examined the prevalence, use patterns (dosage, administration route, duration of effects), and associated adverse events of classic, novel and herbal opioids. The second part delved into detailed retrospective experiences of survey responders with an opioid of preferred choice, mostly kratom. Results: Between May 2020 and February 2023, 467 respondents started the survey, of which 310 met the inclusion criteria. Of these, 52 % (N = 161) completed the first part, 65.6 % (N = 105) started the second part of which 72 completed. Most respondents were male, highly educated, based in North America or Europe, often using multiple opioids. A total of twenty-seven different compounds were reported, of which hydrocodone/dihydrocodeine, kratom, acetylfentanyl, and U-47700 were used the most. A wide range of doses was reported for each compound. Median effect durations ranged between 3 and 4 h for most of the compounds. Administration routes varied, with oral intake being most prevalent. Fentanyl analogues were often administered intravenously. Physical/psychological adverse events were frequently reported by users of oxycodone, kratom, acetylfentanyl, and U-47700. User reports revealed that both kratom and classic opioids were used for recreational and medical purposes, including ameliorating pain, addiction/withdrawal, anxiety, and mood enhancement. Conclusion: Psychological and physical adverse events were widely present among classic, novel and herbal opioids suggesting a need for risk monitoring worldwide. Similarities between classic opioids and kratom include medical utility as well as addictive potential.