"Classic opioids are natural and synthetic compounds (Platosz et al., 2020; Reisfield et al., 2007; Vearrier and Grundmann, 2021) such as prescription opioids commonly utilized for pain management (e.g., morphine and oxycodone) (Hales et al., 2020; Reuben et al., 2015; Vearrier and Grundmann, 2021; Volkow and McLellan, 2016), and other substances (e.g., heroin, initially marketed as an anti-tussive medication) that are used recreationally (Fattore et al., 2008; Platosz et al., 2020; Reisfield et al., 2007; Vearrier and Grundmann, 2021)."
Elisabeth Prevete, Natasha L. Mason, Kim P. C. Kuypers, Eef L. Theunissen, Pablo Mallaroni, Massimo Pasquini, Johannes G. Ramaekers, Use patterns of classic, novel, and herbal opioids, Emerging Trends in Drugs, Addictions, and Health, Volume 5, 2025, 100166, ISSN 2667-1182, doi.org/10.1016/j.etdah.2024.100166.