Undeclared Kratom Alkaloids and Tianeptine in Products Labeled as Cat's Claw
- 1National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38655, USA
Abstract
Background High-concentration 7-hydroxymitragynine (7-OH) products have been described by the US Food and Drug Administration as an emerging public health concern, and in August 2026 the Drug Enforcement Administration temporarily placed mitragynine pseudoindoxyl (MPI), MGM-15 (dihydro-7-hydroxymitragynine), and MGM-16 in schedule I. Since July, Utah and Tennessee officials have reported overdoses, deaths, and laboratory findings involving tablets labeled as cat’s claw ( Uncaria tomentosa ), an herbal supplement without known opioid activity. Chemical data on such products are scarce, and labels do not tell consumers what the products actually contain, including semi-synthetic opioids. Methods In a cross-sectional analysis, we purchased 46 chewable or unit-dose products labeled as containing cat’s claw from online retailers and three different gas stations in Mississippi during September 2026. The products represented 17 brands. Methanol extracts were analyzed by ultra-high-performance liquid chromatography with photodiode array detection and compared with a methanol extract of botanically verified U tomentosa bark. Liquid chromatography quadrupole time of flight mass spectrometry identified additional compounds, and compounds were quantified against authentic reference standards. Proportions are reported with exact (Clopper-Pearson) 95% CIs. Results None of the 46 products declared kratom alkaloids or their derivatives, yet all contained at least one component. Mitragynine was quantified in 41 products (89%; 95% CI, 76% to 96%), 7-OH in 35 (76%; 95% CI, 61% to 87%), MGM-15 in 24 (52%; 95% CI, 37% to 67%), and MPI in 22 (48%; 95% CI, 33% to 63%). A total of 39 products (85%; 95% CI, 71% to 94%) contained MPI or MGM-15, which are temporarily controlled in schedule I. Tianeptine, an antidepressant not approved in the US, was present in five products (11%; 95% CI, 4% to 24%) at 27.9 to 40.2 mg per unit. The 7-OH content ranged from 0.01 to 95.4 mg per unit. Eight products carrying claims such as “NO KRATOM and No 7-OH” or “NO 7-OH” contained mitragynine and 7-OH. Conclusions Labels gave consumers no reliable guide to exposure. Clinicians evaluating unexplained opioid toxicity after use of a cat’s claw product should consider kratom-derived opioids and tianeptine. Regulators may need product testing and label enforcement in addition to scheduling of individual compounds.
Related
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- Quantification of kratom alkaloids mitragynine, 7-hydroxy mitragynine, mitragynine pseudoindoxyl, and dihydro-7-hydroxy mitragynine in forensic casework and medicolegal death investigations.
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- Enhancement of hippocampal synaptic AMPA receptor function by the antidepressant tianeptine and by opioid peptides.
- Associations Between Kratom (Mitragyna Speciosa) Use and Real-Time Anxiety and Sadness: A 15-Day Ecological Momentary Assessment Study
BibTeX
@misc{avula2026undeclared,
title = {{Undeclared Kratom Alkaloids and Tianeptine in Products Labeled as Cat's Claw}},
author = {B. Avula and K. Katragunta and K. K. Tatapudi and J.-Y. Bae and A. G. Chittiboyina and I. A. Khan},
howpublished = {medRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.16.26365420},
url = {https://www.medrxiv.org/content/10.64898/2026.10.16.26365420v1},
note = {Public domain},
}
RIS
TY - UNPB
TI - Undeclared Kratom Alkaloids and Tianeptine in Products Labeled as Cat's Claw
AU - B. Avula
AU - K. Katragunta
AU - K. K. Tatapudi
AU - J.-Y. Bae
AU - A. G. Chittiboyina
AU - I. A. Khan
PY - 2026
DA - 2026/10/16
PB - medRxiv
DO - 10.64898/2026.10.16.26365420
UR - https://www.medrxiv.org/content/10.64898/2026.10.16.26365420v1
AB - Background High-concentration 7-hydroxymitragynine (7-OH) products have been described by the US Food and Drug Administration as an emerging public health concern, and in August 2026 the Drug Enforcement Administration temporarily placed mitragynine pseudoindoxyl (MPI), MGM-15 (dihydro-7-hydroxymitragynine), and MGM-16 in schedule I. Since July, Utah and Tennessee officials have reported overdoses, deaths, and laboratory findings involving tablets labeled as cat’s claw ( Uncaria tomentosa ), an herbal supplement without known opioid activity. Chemical data on such products are scarce, and labels do not tell consumers what the products actually contain, including semi-synthetic opioids. Methods In a cross-sectional analysis, we purchased 46 chewable or unit-dose products labeled as containing cat’s claw from online retailers and three different gas stations in Mississippi during September 2026. The products represented 17 brands. Methanol extracts were analyzed by ultra-high-performance liquid chromatography with photodiode array detection and compared with a methanol extract of botanically verified U tomentosa bark. Liquid chromatography quadrupole time of flight mass spectrometry identified additional compounds, and compounds were quantified against authentic reference standards. Proportions are reported with exact (Clopper-Pearson) 95% CIs. Results None of the 46 products declared kratom alkaloids or their derivatives, yet all contained at least one component. Mitragynine was quantified in 41 products (89%; 95% CI, 76% to 96%), 7-OH in 35 (76%; 95% CI, 61% to 87%), MGM-15 in 24 (52%; 95% CI, 37% to 67%), and MPI in 22 (48%; 95% CI, 33% to 63%). A total of 39 products (85%; 95% CI, 71% to 94%) contained MPI or MGM-15, which are temporarily controlled in schedule I. Tianeptine, an antidepressant not approved in the US, was present in five products (11%; 95% CI, 4% to 24%) at 27.9 to 40.2 mg per unit. The 7-OH content ranged from 0.01 to 95.4 mg per unit. Eight products carrying claims such as “NO KRATOM and No 7-OH” or “NO 7-OH” contained mitragynine and 7-OH. Conclusions Labels gave consumers no reliable guide to exposure. Clinicians evaluating unexplained opioid toxicity after use of a cat’s claw product should consider kratom-derived opioids and tianeptine. Regulators may need product testing and label enforcement in addition to scheduling of individual compounds.
ER -