Pharmacokinetics of single- and multiple-dose roflumilast: an open-label, three-way crossover study in healthy Chinese volunteers

PURPOSE: To determine the pharmacokinetic properties of the common tablet of roflumilast administered in single and multiple oral doses in Chinese subjects. SUBJECTS AND METHODS: Both the single- and multiple-dose studies included 12 adults (6 males and 6 females). In this single-center, open-label study, single doses of 0.25, 0.375, and 0.5 mg were administered using a randomized, three-way crossover design, and then, the 0.375 mg dose was continued for 11 days once daily. The pharmacokinetic parameters for roflumilast and roflumilast N-oxide were determined and the safety evaluation included adverse events assessed by monitoring, physical examination, vital sign tests, and clinical laboratory tests. RESULTS: After every single dose, the time to the maximum concentration (C(max)) of roflumilast (T(max)) was 0.25–2.0 hours; thereafter, the concentration declined, with a mean half-life (t(1/2)) of 19.7–20.9 hours over the range of 0.25–0.50 mg. As for roflumilast N-oxide, the mean t(1/2) was 23.2–26.2 hours. The area under curve from the beginning to 24 hours (AUC(0–24 h)), the AUC until infinity (AUC(inf)), and the C(max) of roflumilast and roflumilast N-oxide increased in a dose-proportional manner. After multiple doses, the accumulation index (R(ac)) on the 11th day of the steady state was ~1.63 for roflumilast and 3.20 for roflumilast N-oxide. No significant sex differences were observed in the pharmacokinetic parameters of roflumilast and roflumilast N-oxide. In addition, there were no serious adverse events across the trial. CONCLUSION: Roflumilast was safe and well-tolerated in healthy volunteers, and a linear increase in its C(max) and AUC values was observed at doses ranging from 0.25 to 0.50 mg.