Therapeutic drug management
Trough levels are most reproducible
Dk green heparin (Li or Na), no gel
Immediately following collection, mix sample by inverting 8 - 10 times to prevent clotting.
Refrigerated (preferred)
Ambient - <3 days
Frozen - OK
Gel-barrier tubes are not recommended
Liquid chromatography/tandem mass spectrometry (LC/MS-MS)
Plasma insulin concentrations have been shown to increase only when plasma glipizide concentrations exceeded 200 ng/mL.
Toxic range has not been established