title: Pharmacokinetics and bioequivalence evaluation of two different atorvastatin calcium 10-mg tablets: A single-dose, randomized-sequence, open-label, two-period crossover study in healthy fasted Chinese adult males.
abstract: BACKGROUND
  Atorvastatin calcium is a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor indicated for the prevention of cardiovascular disease and for the treatment of dyslipidemia. Information on the pharmacokinetics of atorvastatin in a Chinese population is lacking, and regulatory requirements necessitate a bioequivalence study for the marketing of a generic product in China.
  
  
  OBJECTIVE
  The aim of the present study was to assess the pharmacokinetics and bioequivalence of a test and branded reference formulation of atorvastatin calcium 10-mg tablets in healthy fasted Chinese male volunteers.
  
  
  METHODS
  This was a single-dose, randomized-sequence, open-label, 2-period crossover study with a 2-week washout period between doses. Healthy Chinese males were randomly assigned to receive 20 mg of either the test or reference formulation, and 13 blood samples were obtained over a 48-hour interval. Plasma concentrations of parent atorvastatin and ortho-hydroxy-atorvastatin (primary active metabolite) were simultaneously determined using a validated liquid chromatography-isotopic dilution mass spectrometry method. Pharmacokinetic parameters, including C(max), T(max), t((1/2)), AUC(0-t), and AUC(0-infinity)), were calculated. The 2 formulations were to be considered bioequivalent if 90% CIs for the log transformed ratios of AUC and C(max) of atorvastatin were within the predetermined bioequivalence range (0.80-1.25 for AUC and 0.70-1.43 for C(max)) as established by the State Food and Drug Administration of China. Tolerability was evaluated throughout the study by vital signs monitoring, physical examinations, 12-lead ECGs, and subject interviews on adverse events (AEs).
  
  
  RESULTS
  A total of 66 subjects were assessed for inclusion; 20 were excluded prior to study initiation. Of the 46 healthy subjects (mean [SD] age, 24.1 [2.5] years; height, 170.8 [5.1] cm; weight, 64.6 [6.4] kg; body mass index (BMI), 22.1 [1.7] kg/m(2)) who completed the study, 45 subjects (mean [SD] age, 24.1 [2.5] years; height, 171.1 [4.9] cm; weight, 64.8 [6.3] kg; BMI, 22.1 [1.7] kg/m(2)) were included in the pharmacokinetic and bioequivalence analyses; 1 subject was excluded from these analyses because he mistakenly received the same formulation in both periods. No period or sequence effect was observed. The mean values of C(max), AUC(0-t), and AUC(0-infinity)) for the test and reference formulations of atorvastatin (8.78 and 10.76 ng/mL, 38.22 and 40.02 ng/mL/h, 42.73 and 44.51 ng/mL/h, respectively) and ortho-hydroxy-atorvastatin (5.78 and 5.77 ng/mL, 47.32 and 48.47 ng/mL/h, 52.36 and 53.14 ng/mL/h) were not significantly different. The 90% CIs for natural log-transformed ratios of C(max), AUC(0-t), and AUC(0-infinity)) of both atorvastatin (0.73-0.91, 0.92-1.02, and 0.91-1.01, respectively) and ortho-hydroxy-atorvastatin (0.83-1.05, 0.92-1.02, and 0.93-1.02) were within the bioequivalence acceptance limits. Three subjects (6.5%) reported a total of 4 mild AEs (1 abdominal discomfort and 3 venipuncture syncope), which were not considered to be associated with administration of the study drug.
  
  
  CONCLUSIONS
  This single-dose (20 mg) study found that the test and reference formulations of atorvastatin calcium 10-mg tablet met the regulatory definition for assuming bioequivalence in these healthy fasted Chinese male volunteers. Both formulations were generally well tolerated in the population studied. Chinese National Registry Code: 2007L02512.
authors.affiliation: Shanghai Xuhui Central Hospital, China. yanmeiliu25@gmail.com
authors.forename: Yan-Mei
authors.initials: YM
authors.lastname: Liu
authors.forename: Hua-Hua
authors.initials: HH
authors.lastname: Pu
authors.forename: Gang-Yi
authors.initials: GY
authors.lastname: Liu
authors.forename: Jing-Ying
authors.initials: JY
authors.lastname: Jia
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Weng
authors.forename: Rong-Jing
authors.initials: RJ
authors.lastname: Xu
authors.forename: Guo-Xiu
authors.initials: GX
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Meng-Qi
authors.initials: MQ
authors.lastname: Zhang
authors.forename: Chuan
authors.initials: C
authors.lastname: Lu
authors.forename: Chen
authors.initials: C
authors.lastname: Yu
mesh_terms: D000284:Administration, Oral; D000328:Adult; D019540:Area Under Curve; D044466:Asian People; D000069059:Atorvastatin; D002681:China; D018592:Cross-Over Studies; D016568:Drugs, Generic / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D006207:Half-Life; D006538:Heptanoic Acids / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D008297:Male; D011758:Pyrroles / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D013607:Tablets; D013810:Therapeutic Equivalency; D055815:Young Adult
chemical_list: D016568:Drugs, Generic; D006538:Heptanoic Acids; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011758:Pyrroles; D013607:Tablets; D000069059:Atorvastatin