The pharmacologic effects of recombinant, human colony-stimulating factors and their modulation by theophylline.
STUDY OBJECTIVES: To investigate the effect of colony-stimulating factors (CSFs) on drug metabolism using theophylline as a substrate (phase I), and to evaluate the influence of theophylline on endogenous serum cytokine concentrations (phase II). DESIGN: Open-label, prospective study. SETTING: The bone marrow transplant unit of a tertiary university teaching hospital. PATIENTS: Thirty-seven women with breast cancer (28 phase I, 9 phase II). INTERVENTIONS: Patients received aminophylline 0.58 mg/kg either as a 30-minute intravenous infusion before receiving recombinant CSFs or after several days of CSF therapy, just before high-dose chemotherapy (phase I) or as a continuous intravenous infusion after bone marrow transplantation (phase II). MEASUREMENTS AND MAIN RESULTS: Clearance of theophylline was significantly higher after CSF administration (0.76 vs 0.99 ml/min/kg, p = 0.019). Continuous infusion of aminophylline resulted in elevations of serum macrophage-CSF and interleukin 6. CONCLUSIONS: Administration of CSFs before autologous bone marrow transplantation for priming progenitor cells may alter drug metabolism. Studies should be conducted to evaluate the potential effects of CSFs on the disposition of chemotherapeutic agents.