BACKGROUND AND OBJECTIVES:Ranolazine was approved by the US Food and Drug Administration in January 2006 for the treatment of chronic angina pectoris, and is the first approved agent from a new class of anti-anginal drugs in almost 25 years. The primary objective of this study was to determine the concentration of ranolazine in human plasma using the liquid chromatography/tandem mass spectrometry (LC-MS/MS) method and to compare the pharmacokinetic properties of ranolazine after administration of single and multiple doses of ranolazine in healthy Chinese adult volunteers. METHODS:A randomized, open-label, single- and multiple-dose study design was used in the study. Subjects were randomized to receive a single dose of 500, 1,000, or 1,500 mg of ranolazine. Those who received the single dose continued on to the multiple-dose phase and received 500 mg twice daily for 7 days. In the single-dose phase, blood samples were collected from 0 to 48 h after drug administration. In the multiple-dose phase, samples were obtained before drug administration at 8:00 am and 8:00 pm on days 6 and 7 to determine the minimum steady-state plasma concentration (C(min,ss)) of ranolazine; on day 8, samples were collected from 0 to 48 h after drug administration. All values were expressed as means (standard deviations [SDs]). Adverse events (AEs) were monitored throughout the study via subject interview, vital signs, and blood sampling. RESULTS:The LC-MS/MS method was developed and validated. Twelve Chinese subjects (six men, six women) were enrolled in the single-dose phase of the pharmacokinetic study. The mean (SD) age of the subjects was 24.7 (1.6) years; their mean (SD) weight was 61.3 (6.4) kg, their mean (SD) height was 165.7 (4.5) cm, and their mean (SD) body mass index was 21.6 (6.6) kg/m(2). The main pharmacokinetic parameters [mean (SD)] for ranolazine after administration of a single oral dose of 500, 1,000, and 1,500 mg were as follows: maximum plasma concentration (C(max)) 741.5 (253.0), 1,355.0 (502.0), and 2,328.7 (890.5) ng/mL, respectively; area under the concentration-time curve from time zero to 48 h (AUC(48)) 9,071.9 (3,400.0), 16,573.5 (6,806.2), and 29,324.5 (10,857.2) ng·h/mL; AUC from time zero extrapolated to infinity (AUC(∞)) 9,826.7 (3,152.0), 16,882.4 (6,790.8), and 29,923.5 (10,706.3) ng·h/mL; time to reach C(max) (t(max)) 5.3 (1.4), 4.2 (1.2), and 5.9 (2.8) h; elimination half-life (t(½)) 6.4 (3.3), 6.4 (3.5), and 6.7 (4.3) h. Mean (SD) values for the main pharmacokinetic parameters for ranolazine after administration of multiple doses were as follows: steady-state C(max) (C(max,ss)) 1,732.9 (547.3) ng/mL; C(min,ss) 838.1 (429.8) ng/mL; steady-state AUC at time t (AUC(ss,(t))) 14,655.5 (5,624.2) ng·h/mL; average steady-state plasma drug concentration during multiple-dose administration (C(av,ss)) 1,221.3 (468.7) ng/mL; t(max) 3.46 (1.48) h; t(½) 6.28 (2.48) h. CONCLUSION:In this group of healthy Chinese subjects, AUC and C(max) increased proportionally with the dose, whereas t(½) was independent of the dose. The pharmacokinetic properties of ranolazine were linear after administration of single oral doses of 500 to 1,500 mg. Compared with the pharmacokinetic parameters of the subjects who received a single dose, those who received multiple doses (twice daily) of ranolazine had a larger AUC from time zero to the time of the last measurable concentration (AUC(last)), AUC(∞), C(max), and apparent total body clearance of drug from plasma after oral administration (CL/F), and shorter t(max) (all p < 0.05). Furthermore, some of the main pharmacokinetic parameters of ranolazine may reflect ethnic differences. This dosage was generally well tolerated by all the subjects.