Postmortem distribution of mitragynine and 7-hydroxymitragynine in 51 cases

Area of Science:

• Forensic Toxicology
• Pharmacology
• Analytical Chemistry

Background:

• Mitragynine (kratom) prevalence is increasing in forensic cases.
• Kratom is used for stimulant and sedative effects.
• Understanding mitragynine distribution and stability is crucial for interpretation.

Purpose of the Study:

• Investigate mitragynine and 7-hydroxymitragynine distribution in postmortem specimens.
• Assess the stability of these compounds in different matrices and storage conditions.

Main Methods:

• Analysis of fluid and tissue specimens from 51 postmortem cases.
• Comparison of central and peripheral blood concentrations.
• Stability studies of mitragynine and 7-hydroxymitragynine under refrigerated and frozen conditions.

Main Results:

• Average heart blood to femoral blood ratios suggest mitragynine postmortem redistribution (1.37 for mitragynine, 1.08 for 7-hydroxymitragynine).
• High mitragynine to 7-hydroxymitragynine ratios observed in blood, vitreous humor, and urine.
• Mitragynine stable for 30 days refrigerated; 7-hydroxymitragynine stable for 7 days (loss <20%).
• 7-hydroxymitragynine degraded over 50% after 60 days refrigerated storage.
• Both compounds stable in methanolic preparations at -20°C for 3 months.

Conclusions:

• Mitragynine exhibits postmortem redistribution, though not statistically significant compared to its metabolite.
• Mitragynine is more stable than 7-hydroxymitragynine in refrigerated biological samples.
• Stability findings impact interpretation of toxicological results in postmortem investigations.