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Stability of pain-related medications, metabolites, and illicit substances in urine.

Author(s): Gonzales E, Ng G, Pesce A, West C, West R, Mikel C, Latyshev S, Almazan P

Publication: Clin Chim Acta, 2013, Vol. 416, Page 80-5

PubMed ID: 23200822 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study investigated the effects of storage at 4˚C or -20˚C with or without a freeze-thaw cycle on the levels of 33 compounds that were spiked into urine from one healthy patient. Thirty-three different medications, metabolites, and illicit drugs were added at two different concentrations to urine aliquots. Two aliquots at each concentration were analyzed immediately or after 2, 3, and 6 months at 4 and -20˚C. Additional aliquots stored at -20˚C were analyzed with a freeze-thaw cycle. Levels were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) for each time-point and the percent difference from aliquots not subjected to storage was determined.

   Summary of Findings:

   Changes in levels of morphine, hydromorphone, EDDP, fentanyl, and alpha-hydrocyalprazolam were limited to less than 10%, regardless of storage temperature, storage duration, and freeze-thaw cycling. Levels of codeine, hydrocodone, oxycodone, oxymorphone, norfentanyl, meperidine, normeperidine, propoxyphene, tramadol, tenpentadol, and nordiazepam changed by less than 20% regardless of storage temperature or duration or freeze-thaw cycling. Although changes in lorezapam, buprenorphine, and norbuprenorphine were generally less than 20%, they declined by 21%,25% and 24%, respectively after 2 months of storage at -20˚C when subjected to a freeze-thaw cycle. Levels of methadone declined by >20% when stored at 4 or -20˚C for 2 months with a freeze-thaw cycle, but changes were limited to less than 10% when stored for longer, regardless of freeze-thaw-cycling. Similarly, levels of norpropoxyphene declined by >20% when stored at 4 or -20˚C for 2 months, regardless of freeze-thaw cycling and when stored at -20˚C for 3 months with freeze-thaw cycling, but declined by less than 10% when stored at 4 or -20˚C for 6 months, regardless of freeze-thaw cycling. Levels of 7-amino-clonazepam declined significantly with storage at 4˚C (-43% after 2 months, -52% after 3 months, and -58% after 6 months), but changed by <15% during storage at -20˚C, regardless of freeze-thaw cycling. 

   Biospecimens

   • Bodily Fluid - Urine

   Preservative Types

   • None (Fresh)
   • Frozen

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   Small molecule	LC-MS or LC-MS/MS

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Storage duration	0 months 2 months 3 months 6 months
   Storage	Freeze/thaw cycling	0 cycles 1 cycle
   Storage	Storage temperature	4˚C -20˚C

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