Comparative pharmacokinetic evaluation and bioequivalence study of three different formulations of Imatinib Mesylate in CML patients

BACKGROUND Imatinib is known as the drug of choice for treatment of chronic myeloid leukemia (CML). For adults the recommended daily dosage of 400 mg requires simultaneous intake of up to four capsules or tablets each 100 mg. A new 400 mg film coated tablet developed due to the need to swallow multiple capsules or tablets per dose and that was a negative impact on treatment adherence. SUBJECTS AND METHODS A group of 36 patients were randomly assigned to receive Imatinib as 4×100 mg capsules, 4×100 mg tablets and 1×400 mg tablet. Blood sampling was performed for up to 48 h after first dosing. After that, subjects were monitored to assess drug related adverse events. Pharmacokinetic parameters were assessed using concentration-time curves for plasma Imatinib and its metabolite. RESULTS Mean area under the curve (AUC (0-∞)) values were 27011, 25811 and 25699 ng/ml for 4×100 mg capsules, 4×100 mg tablets and 1×400 mg tablets, respectively. Cmax values were 1548, 1605 and 1622 ng/ml and t1/2 values were 15.7, 15.8 and 15.6 h. The Test/Reference ratios for AUC (0-∞), AUC (0-48), and Cmax were 0.99, 0.99 and 1.02 for 4×100 mg tablets versus 4×100 mg capsules and 0.96, 0.96 and 0.99 for 1×400 mg tablet versus 4×100 mg capsules. The 95% confidence intervals were fully contained within the accepted interval. The mild and moderate adverse events considered to be drug related were reported. These events showed no clustering by type of dosage form and were of little to no clinical significance. CONCLUSION Film coated (400 mg) tablet dosage formulations of Imatinib is bioequivalent to the commercial available 100 mg hard gelatin capsule, and is as safe and well tolerated.