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Order Code BUAUC Busulfan, Intravenous Dose, Area Under the Curve, Plasma

Reporting Name

Busulfan, IV Dose, AUC, P

Useful For

Guiding dosage adjustments to achieve complete bone marrow ablation while minimizing dose-dependent toxicity

Profile Information

Test ID Reporting Name Available Separately Always Performed
DOSE Busulfan, IV Dose, AUC, P No Yes
BU2H Busulfan, Immediate Post Infusion No Yes
BU3H Busulfan, 1hr Post Infusion No Yes
BU4H Busulfan, 2hr Post Infusion No Yes
BU6H Busulfan, 4hr Post Infusion No Yes

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Plasma Na Heparin


Necessary Information


The time the drug administration is started and completed, the patient's dose (mg every 6 hours), body weight (kg), and age (years) must be submitted with the specimens. Without infusion start time, exact time of specimen collection, dose, and body weight, the area under the curve and clearance cannot be calculated. Age is required for assessment of the correct dose per body weight.

 

A completed Busulfan Information: Mail-In Specimen Instructions (T559) is required.



Specimen Required


Four plasma specimens with different collection times (keep all specimens under 1 order) are required.

 

Collection Container/Tube: Green top (sodium heparin) (Plasma gel/PST are not acceptable)

Submission Container/Tube: Plastic vials

Specimen Volume: 1 mL

Collection Instructions:

1. The first specimen should be collected immediately after completion of the first intravenous infusion of 0.8 mg/kg busulfan.

2. Additional specimens should also be collected at 1 hour, 2 hours, and 4 hours after completion of infusion.

3. Label each specimen with exact time of collection.

4. Busulfan degrades quickly at ambient temperature. Specimens must be kept in wet ice slurry or refrigerated at 4° C. Specimens must be centrifuged within 2 hours after collection. Separate the plasma and transfer to individual 5-mL plastic vials, labeled with exact time of collection. Immediately freeze at -20° C.

Additional Information:

This test should only be ordered when the following criteria are met:

-Busulfan dosing protocol must be intravenous administration of 0.8 mg/kg doses every 6 hours over 4 days, for a total of 16 doses

Specimens must be collected as described below:

-1 specimen collected immediately after completion of the first 2-hour IV infusion of busulfan

-1 specimen collected 1 hour after the infusion is completed

-1 specimen collected 2 hours after the infusion is completed

-1 specimen collected 4 hours after the infusion is completed and prior to the next infusion of busulfan


Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Heparin Frozen (preferred) 28 days
  Refrigerated  72 hours

Reference Values

AREA UNDER THE CURVE

900-1500 (mcmol/L)(min)

 

CLEARANCE

2.1-3.5 (mL/minute)/kg

Day(s) Performed

Monday through Saturday

CPT Code Information

80299 x 4

Method Description

Busulfan analysis is performed by liquid chromatography tandem mass spectrometry with calculation of area under the curve (AUC) by integration of the time versus concentration curve from start of infusion to last specimen collection (6-hour AUC).(Unpublished Mayo method)

 

The AUC and clearance are calculated after quantification of busulfan concentration in plasma samples collected at specific time points after the initial infusion.

 

The AUC is calculated by integration of the plot of time in minutes from the start of infusion until the last specimen collection (independent variable), with busulfan concentration in mcmol/L (dependent variable) and straight-line extrapolation of the immediate postinfusion busulfan concentration to time zero. Clearance is calculated as the dose divided by AUC.

 

The recommended optimal dose is calculated based on the assumption of an ideal AUC=1100 mcmol*min.(Slattery JT, Risler LJ. Therapeutic monitoring of busulfan in hematopoietic stem cell transplantation. Ther Drug Monit. 1998;20[5]:543-549)

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Forms

1. Busulfan Information: Mail-In Specimen Instructions (T559) is required

2. If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.