Autoinjector stability

Autoinjector stability was carried out for over 13 h by repeated injection of the same extracted plasma sample at room temperature (nominally 25 °C) The results showed, that the extracted specimens remained stable over the course of the study. QC samples containing 120 and 2000 ng/mL DEC in plasma were subjected to 3 freeze/thaw cycles. Samples were frozen at -20 °C for 24 h and thawed unassisted at room temperature. 

The assay has been validated and the results of validation demonstrate that the standard curve is linear over the concentration range of 100-2000 ng/mL. The assay is reproducible and accurate, with recovery of the analyte and internal standard in the range of 80-90 %. The analysis requires 0.5 mL of plasma and has a limit of quantification of 70 ng/mL. The stability of plasma samples stored at -20 °C has been demonstrated for up to 12 weeks. Autoinjector stability has been demonstrated for over 13 h and freeze-thaw stability has been demonstrated for 3 freeze-thaw cycles. The procedure has a sample throughput of at least 30 specimens per day. The assay meets the guidelines for bioanalytical methods validation for human studies (Shah et al. 1991). 

TIP Autoinjectors provide reliable injection of the desired volume of sample to HPLCs, GCs, and other instrumentation. This equipment allows assays to be readily standardized, eliminating many potential questions about assay reproducibility. The stability of sample preparations in the injector queue must be considered when examining data from an extended run. 

To circumvent the problem of limited stability of HI 6 and HLo 7, dry/wet autoinjectors have been developed in which the unstable oxime is dissolved by an atropine-containing diluent in an adjacent chamber upon activation of the device (Schlager et al., 1991 Thiermann et al., 1994,1995). Such devices, filled with 500 mg of HI 6 dichloride and 2 mg of atropine sulfate, are now on the market for military use and were fielded by the Canadian troops in the Second Gulf War (Dawson, 1994). While the pharmaceutical stability may be sufficient and a shelf-life of 5 years has been envisaged (Brodin and Wellen-stam, 1996), HI 6 dichloride appears less suitable... 

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