Conclusions
While significant effects of the covariates were observed in this study, the magnitude of these effects on systemic exposure is not large enough to warrant FF/VI dosage adjustment in patients with COPD.
Methods
Population pharmacokinetic methods that maximize the likelihood of all data were developed to describe systemic exposure to FF and VI following once-daily FF/VI, FF, or VI, and to identify significant covariates that impact the pharmacokinetics. COPD patients (N = 1225 for the FF analysis and N = 1091 for the VI analysis; 94 and 93 % of total data, respectively) and healthy subjects contributed to the analysis.
Results
FF data were described by a two-compartment model with first-order absorption and elimination. The population grouping "race" was a significant covariate on inhaled clearance (CL/F). The area under the curve over 24 h (AUC0-24) for FF was higher for East Asian, Japanese, and South East Asian (average 23-30 %) and Asian Central, White Arabic, American Indian/Native Alaskan, and 'other' (10-26 %) subjects compared with White/Caucasians. VI pharmacokinetics were described by a three-compartment model with zero-order absorption and first-order elimination. Significant demographic covariates identified to affect pharmacokinetics of VI were age [on CL/F and central volume (V 1/F)], bodyweight (on CL/F), sex and smoking (on V 1/F). Conclusions: While significant effects of the covariates were observed in this study, the magnitude of these effects on systemic exposure is not large enough to warrant FF/VI dosage adjustment in patients with COPD.