Combined administration of G-CSF and dexamethasone for the mobilization of granulocytes in normal donors: optimization of dosing.

BACKGROUND

The clinical utility of neutrophil (polymorphonuclear leukocyte, PMN) transfusion therapy has been compromised, in part, by the inability to obtain sufficient quantities of functional neutrophils from donors. Mobilization of PMNs in the peripheral blood of normal volunteers has been shown to be superior when G-CSF is administered in conjunction with dexamethasone to that when either agent is administered alone. The current study was conducted to determine the optimal dosages of G-CSF and dexamethasone to be administered to donors in a granulocyte transfusion program.

STUDY DESIGN AND METHODS

Five normal subjects were randomly assigned to each of the following single-dose regimens over five consecutive weeks: 1) subcutaneous (SC) G-CSF at 600 microg and oral (PO) dexamethasone at 8 mg; 2) SC G-CSF at 450 microg and PO dexamethasone at 8 mg; 3) SC G-CSF at 450 microg and PO dexamethasone at 12 mg; 4) SC G-CSF at 450 microg; and 5) PO dexamethasone at 12 mg. Venous blood was collected at 0, 6, 12, and 24 hours after drug administration for determination of absolute neutrophil count (ANC). Side effects of drug administration were recorded by using a standardized symptom questionnaire.

RESULTS

Maximal ANC was achieved at 12 hours after administration of drugs under each regimen. All four regimens containing G-CSF caused greater than 10-fold increases in the ANC. When administered in conjunction with dexamethasone, G-CSF resulted in statistically similar PMN mobilization at dosages of 450 microg and 600 microg. The combined single-dose regimen of SC G-CSF at 450 microg and PO dexamethasone at 8 mg increased the mean ANC from a baseline value of 2800 per microL to 37,900 per microL at 12 hours after administration. This regimen was well tolerated by the normal volunteers.

CONCLUSION

In a single-dose format designed for clinical granulocyte transfusion programs, optimal PMN mobilization can be achieved in normal donors with a combined regimen of SC G-CSF at 450 microg, and PO dexamethasone at 8 microg.