[Storage stability of flunitrazepam, flurazepam, diazepam and metabolites in blood and plasma]

The stability of flunitrazepam, flurazepam, diazepam and some of their metabolites in spiked blood and plasma samples was studied bei GC-ECD analysis at defined time intervals up to 240 days. Validation data of the method are given. The blood or plasma samples were stored either at 22 degrees C or at 4 degrees C, and were exposed to global natural light irradiation or protected from light. All substances considerably decreased during the time interval studied. Flunitrazepam soon disappeared completely at room temperature (22 degrees C), while diazepam and flurazepam proved to be more stable, but a clear pattern of breakdown could not be established. The data obtained suggest a result from a long-term stored sample to be cautiously interpreted. Further investigation concerning the stability of drugs and the establishment of optimal storage conditions seem necessary.