Long-term stability of morphine, codeine, and 6-acetylmorphine in real-life whole blood samples, stored at -20°C.
OBJECTIVE
Stability of drugs during storage is important in forensic toxicology. For the analytes detected after intake of heroin (6-acetylmorphine (6-AM), morphine and codeine), long-time stability in real life whole blood samples are studied in only a small number of cases.


METHODS
Whole blood post mortem (n=37) and whole blood samples from living persons (n=22) containing morphine and codeine as well as 6-AM in blood or urine were selected. All cases represented intake of heroin. All samples contained fluoride and were initially analysed and stored in normal conditions (-20°C) for 4-9 years. All samples were then reanalysed using the same analytical methods and the results were compared.


RESULTS
For samples from living persons, the median change in concentration was -3.7% for morphine and -5.3% for codeine. For post mortem samples, the median change in concentration was -12% for morphine and -11% for codeine. Both for samples from living persons and post mortem samples, the decrease in the concentrations from the original analysis to reanalysis were statistically significant for morphine and codeine. Regarding 6-AM, all living samples were negative at reanalysis. For post mortem samples, four cases still tested positive for 6-AM at reanalysis with a median change in the concentrations of -81%. There was no significant change in the morphine to codeine concentration ratios neither for living nor post mortem samples.


CONCLUSIONS
This study showed that in real life whole blood samples, the concentrations of morphine and codeine are relatively stable during long-term storage at -20°C. 6-AM on the other hand, shows a considerable decrease in concentrations that is important to consider when interpreting results from reanalyses of forensic cases.
Norwegian Institute of Public Health, Division of Forensic Medicine and Drug Abuse Research, Pb 4404 Nydalen, 0403 Oslo, Norway; Center for Psychopharmacology, Diakonhjemmet Hospital, Forskningsveien 7, 0319 Vinderen, Norway. Electronic address: Gudrun.Hoiseth@fhi.no.
Gudrun
G
Høiseth
Oslo University Hospital, Department of Medical Biochemistry, Pb 4950 Nydalen, 0424 Oslo, Norway.
Bente
B
Fjeld
Oslo University Hospital, Department of Pharmacology, Pb 4950 Nydalen, 0424 Oslo, Norway.
Margrete Larsen
ML
Burns
Norwegian Institute of Public Health, Division of Forensic Medicine and Drug Abuse Research, Pb 4404 Nydalen, 0403 Oslo, Norway.
Dag Helge
DH
Strand
Norwegian Institute of Public Health, Division of Forensic Medicine and Drug Abuse Research, Pb 4404 Nydalen, 0403 Oslo, Norway.
Vigdis
V
Vindenes
D003061:Codeine / Q000097:blood*; D015925:Cryopreservation; D004355:Drug Stability; D053593:Forensic Toxicology; D006801:Humans; D009020:Morphine / Q000097:blood*; D009022:Morphine Derivatives / Q000097:blood*; D009294:Narcotics / Q000097:blood*; D011180:Postmortem Changes; D013048:Specimen Handling; D013997:Time Factors
D009022:Morphine Derivatives; D009294:Narcotics; D009020:Morphine; C026979:6-O-monoacetylmorphine; D003061:Codeine
6-Monoacetylmorphine; Codeine; Morphine; Stability; Storage