A Descriptive Assessment of Products Containing the Opioid Receptor Stimulator Mitragynine Pseudoindoxyl

Background: Potent semi-synthetic alkaloids that stimulate opioid receptors are being sold to consumers in gas stations, smoke shops, and online as the dietary supplement 'kratom'. Objective: We descriptively evaluated the characteristics of products containing mitragynine pseudoindoxyl. Results: Fifty-one unique products met our inclusion criteria. Seventy-one percent of products contained mitragynine pseudoindoxyl plus 7-hydroxymitragynine, 24% contained mitragynine pseudoindoxyl alone (24%), and 6% contained mitragynine pseudoindoxyl with 8-hydroxymitragynine or 11-hydroxymitragynine (with or without 7-hydroxymitragynine). Sixty-nine percent of products had a child appealing flavoring and/or scent, 63% of products were formulated using bright colors or had bright colors on their labeling, 12% of products had food pictures on the label (mainly representing the fruit or mint flavoring/scent), 6% of products had a cartoon mascot, and 6% of products had a food formulation (ice cream cone or chocolate bar). Only 18% of websites disclosed the products stimulated opioid receptors while 45% disclosed they could cause intoxication, tolerance, dependence, withdrawal, or addiction. Conclusions: There are many products that contain mitragynine pseudoindoxyl sold as dietary supplements and many have features that would appeal to children.