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Assessment of the stability of 30 antipsychotic drugs in stored blood specimens

Eva Saar, Dimitri Gerostamoulos, Olaf H Drummer & Jochen Beyer

abstract The stability of 30 common antipsychotics (APs) in spiked whole blood was investigated over ten weeks in a preliminary experiment (designated "P experiment"). Pools of blank blood spiked with drugs at two different therapeutic levels were stored at four different temperatures: 20 °C, 4 °C, -20 °C, and -60 °C and extracted once weekly in duplicate, using a previously published method. A loss of >15% of the initial drug concentration was considered to indicate possible instability and the respective drugs were selected for further investigation in a final experiment (designated "F experiment"). Eight APs (chlorpromazine, chlorprothixene, fluspirilene, droperidol, olanzapine, thioridazine, triflupromazine, and ziprasidone) were incorporated into the F experiment. The same conditions were used in both experiments, however only a high therapeutic drug concentration was chosen for the F experiment and the storage time was extended to 20 weeks. All drugs of interest in the F experiment showed significant losses after 20 weeks of storage under at least one storage condition. The most notable results involved olanzapine, where losses of almost 100% in all storage temperatures were observed. Drug degradation in fluspirilene samples was significant after 20 weeks under all storage conditions. Overall, extensive degradation was seen with approximately 80% drug loss when stored at 20 °C and 4 °C with samples also seriously affected by degradation of up to 50% when stored at -20 °C and -60 °C, respectively. Ziprasidone remained stable when stored at 4 °C, -20 °C, and -60 °C over 9 weeks, however significant degradation was observed when stored at 20 °C, with a loss of almost 100% after 20 weeks of storage. The time period and temperature of storage of biological samples can have a significant influence on the stability of several APs. It is therefore important to be aware of potential changes in drug concentrations during storage when interpreting analytical results.
   
citation Saar E, Gerostamoulos D, Drummer O H, Beyer J. Assessment of the stability of 30 antipsychotic drugs in stored blood specimens. Forensic Sci Int 2011; 215:152-8.
   
type journal paper/review (English)
date of publishing 26-03-2011
journal title Forensic Sci Int (215/1-3)
ISSN electronic 1872-6283
pages 152-8
PubMed 21441006
DOI 10.1016/j.forsciint.2011.02.022