Single-dose, randomized crossover comparisons of different-strength imatinib mesylate formulations in healthy korean male subjects

Background: Imatinib mesylate is used to treat chronic myeloid leukemia and advanced gastrointestinal stromal tumors. Objective: The purpose of this study was to compare the pharmacokinetics of 2 different strengths of the imatinib formulation containing 100 mg (reference) and 400 mg (test) to satisfy the regulatory requirement for marketing. Methods: A single-center, randomized, single-dose, open-label, 2-period, 2-sequence, comparative crossover study with a 14-day washout period was conducted in 30 healthy male volunteers. Plasma samples for the drug analysis were collected up to 72 hours after drug treatment. Participants received either the reference (4 tablets of 100-mg imatinib) or the test (1 tablet of 400-mg imatinib) formulation during the first period and the alternative formulation during the second period. The safety profiles and tolerability of the 2 formulations were also assessed based on physical examinations, laboratory tests, a 12-lead ECG, and vital signs. Results: Thirty participants were initially enrolled; their mean (SD) age, height, weight, and body mass index were 24.9 (2.0) years (range, 23-30 years), 174 (5) cm (range, 164-185 cm), 69.9 (2.0) kg (range, 54.1-87.4 kg), and 23.0 (2.0) kg/m² (range, 18.5-26.9 kg/m²); 28 healthy participants completed both treatment periods. Two subjects did not complete the study because they withdrew consent for personal reasons. The observed mean (SD) C_max, AUC_0-last, and AUC_0-∞ values for the reference formulation were 1792 (357) ng/mL, 28,485 (6274) ng · h/mL, and 29,079 (6371) ng · h/mL, respectively. Corresponding values for the test formulation were 1710 (312) ng/mL, 27,222 (4624) ng · h/mL, and 27,872 (4751) ng · h/mL. The geometric mean ratios (90% CIs) between the 2 formulations at the 400-mg dose of imatinib were 0.9579 (0.9054-1.0136) for C_max, 0.9652 (0.9174-1.0155) for AUC_0-last, and 0.9679 (0.9203-1.0179) for AUC_0-∞, respectively. During the study period, 6 adverse events (3 for the reference and 3 for the test formulation) were reported; all were transient, mild, and resolved completely during the treatment period. There were 4 cases of nausea and 1 case each of dizziness and oropharyngeal pain. Four adverse events were considered related to the study drugs. Conclusions: The results showed that despite the different strengths of the 2 imatinib formations, the test and reference formulations both met the regulatory criteria for pharmacokinetic equivalence at a dose of imatinib 400 mg in these healthy Korean male subjects. Both imatinib formulations seemed to be generally well tolerated. ClinicalTrials.gov identifier: NCT01270984.