WITHDRAWN: Gastroretentive fibrous dosage forms for prolonged delivery of sparingly-soluble tyrosine kinase inhibitors. Part 4: Experimental validation of the models of in vivo expansion, gastric residence time, and drug concentration in blood

Abstract

In this final part, the models of in vivo expansion, gastric residence time, and drug concentration in blood developed in Part 3 are validated on dogs. Both slow-release gastroretentive fibrous and immediate-release particulate dosage forms containing 200 mg nilotinib were tested. As predicted by the model, in the stomach the fibrous dosage form expanded linearly with time to about 1.5 times the initial radius by 4 h. The expanded dosage form fractured after about 10 h, and then passed into the intestines. The drug concentration in blood exhibited a broad peak with a maximum of 0.5 μg/ml and a width at half-height of 10.2 h. By contrast, after administering the immediate-release capsule the contrast agent particles were expelled from the stomach within 1.5 h. The drug concentration in blood exhibited a sharp peak with a maximum of 0.59 μg/ml and a width at half-height of 3.6 h, a third of that of the fibrous form. The experimental data validate the models reasonably. Thus, upon repeated dosing, the gastroretentive fibrous dosage forms designed in this study enable a steady drug concentration in blood for increasing the efficacy and mitigating side effects of drug therapies.