Trough levels are most reproducible
Dk green heparin (Li or Na), no gel
Immediately following collection, mix by inverting 8 - 10 times to prevent clotting
Ambient (preferred) - 3 days
Refrigerated (OK)
Frozen (OK)
Gel-barrier tubes are not recommended
Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
<235.0 ng/mL peak 45min post dose
≤234 ng/mL observed in trials (30 - 56 mg/day)
Not established