Busulfan PK Monitoring (NCCN HCT-A)
- PK monitoring is REQUIRED for oral busulfan and PREFERRED for IV busulfan.
- Underexposure → relapse ↑ + reduced OS.
- Overexposure → VOD/SOS ↑ + NRM ↑.
| Parameter | Details |
|---|---|
| AUC Target (Total) | 60–100 mg × h/L (most recommendations). Previously reported as µM×min: AUC 5000 µM×min = 20.5 mg×h/L (McCune 2019). |
| Reporting Units | Report as mg×h/L (NCCN standard). AVOID µM×min to prevent conversion errors. |
| When to Do PK | 1st dose PK → adjust subsequent doses to reach target. Requires institutional expertise in real-time busulfan TDM. |
| Oral vs. IV | IV busulfan PREFERRED: more predictable PK, fewer CNS seizure prophylaxis issues, less variability. Oral: higher variability, REQUIRES PK monitoring. |
| Seizure Prophylaxis | Busulfan is EPILEPTOGENIC. Standard: levetiracetam or clonazepam. Phenytoin induces CYP → reduces busulfan exposure. |
BUSULFAN + SEIZURE PPX: Do NOT use phenytoin as seizure prophylaxis with busulfan. Phenytoin induces CYP enzymes → increases busulfan clearance → underexposure → relapse risk. Use levetiracetam (preferred) or clonazepam/lorazepam.
CLINICAL PEARL: Busulfan dose for OBESE patients: mg/kg dosing → use 25% adjusted body weight (IBW + 0.25 × [TBW – IBW]).