De facto opioids: Characterization of novel 7-hydroxymitragynine and mitragynine pseudoindoxyl product marketing.

Background: Within the past year, the online sale of semi-synthetic products containing chemicals derived from mitragynine, kratom's primary alkaloid: 7-hydroxymitragynine (7-OH) and mitragynine pseudoindoxyl (MP) has emerged. Both are highly selective mu opioid receptor agonists undetectable or not present in fresh kratom leaves and may, as constituents of novel product formulations, pose public health risks.

Methods: Between September 2024-February 2025 we abstracted from websites of vendors selling 7-OH and MP products information about these products, including formulation types, dose/serving size, cost, and effect, health, and drug claims

Results: We identified 304 7-OH and MP semi-synthetic products. Most (82.2 %) were 7-OH-only products formulated as chewable/sublingual tablets, shots, or gummies; 14.5 % were combination 7-OH-MP, and 3.3 % MP-only. MP and 7-OH-MP combination products were almost uniformly marketed as "kratom" while 92.0 % of 7-OH-only products were advertised as such. Across products' online marketing content, 73.3 % made effect claims, most often promising increased focus and/or providing relaxation. Functional claims of pain and anxiety relief were made by 37.8 % of products while 12.5 % of made drug claims. The mean cost per recommended dose/serving was $3.97; MP products had a mean cost closer to $5 per recommended dose/serving. Several products had names alluding to prescription opioids.