Aim: To investigate the pharmacodynamics and pharmacokinetics of gemcitabine (dFdC) administered on d 1 and 5 plus cisplatin administered on d 1 in chemonaive patients with stage ⅢB or Ⅳ non-small cell lung cancer (NSCLC).Methods: In each combination cycle, gemcitabine was administered at a dose of 1250 mg/m2 as a 30 min intravenous (iv) infusion on d 1 and 5 followed by cisplatin at a dose of 75 mg/m2as a 3 h iv infusion on d 1 every 3 weeks. There was an interval of 1 h between the two infusions. Clinical response and toxicity of the regimen were observed. Furthermore, the plasma concentrations of gemcitabine(dFdC) and its metabolite (dFdU) at different time points were detected during the first cycle of infusion. Pharmacokinetic software(PKS) was used to estimate the pharmacokinetic parameters of gemcitabine and its metabolite dFdU.Results: A total of 28 patients was enrolled in the study. The median age was 54 years (range 27-75 years), and most patients were in good clinical condition. Twenty-seven patients received two or more treatment cycles. The overall clinical response rate was 33.3%. The median overall survival time was 13 months. The estimated median time to tumor progression (TTP) was 6.2 months, and the 1-year survival rate was 55.6%. Toxicities were tolerated. The main toxicity was myelosuppression; 35.7% of patients had grade 3/4 hematologic toxicities and 28.6% had grade 3/4 non-hematologic toxicities, which were commonly gastrointestinal responses. The pharmacokinetic parameters of dFdC and dFdU were not different between pre-and post-administration of gemcitabine on d 1 and 5. dFdU was minimal (0.729±0.637 μg/mL) before gemcitabine was infused on d 5, and gemcitabine was not present.Conclusion: The regimen is active and well tolerated in chemonaive patients with advanced NSCLC. After gemcitabine was administered on d 1 and 5, the pharmacokinetic parameters of dFdC and dFdU showed no difference from those before the infusion, and dFdU was minimal before gemcitabine was administered on d 5.
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