Formulation and Evaluation of Colchicine Sustained release tablet by using factorial designs

The study on the effect of polymer concentration on in vitro drug release profile revealed that there is a change in vitro drug release parameters (t50, t80, and MDT) with a change in polymer concentration. Fraction of HPMC K4M, HPMC K 100 M, and Ethyl Cellulose were required to be 15, 10, and 7 mg respectively for designing optimized batch F7. The release rate of Colchicine decreased proportionally with an increase in the concentration of ethyl Cellulose and HPMC K100 M. Also the high amount of HPMC K4M leads to the less initial release and sustain effect. A theoretical drug release profile was generated using pharmacokinetic parameters of Colchicine. The value of t50 and t80 of theoretical drug release profile was found to be 242 min and 529 min respectively. The similarity factor f2 was applied between the in vitro drug release profile of optimizing batches and theoretical profile, which indicate a decent similarity between all in vitro drug release profiles (f2 = 68.28 for F7). All the batches except F1shows the value of f2 value within a range. Batch F7 showed the highest f2 (f2 = 68.28) among all the batches and this similarity was also reflected in t50 (≈ 256 min) and t80 (≈ 554 min) values. A 23 full factorial design was applied to systemically optimize in vitro drug release profile. The HPMC K4M (X1), Concentration of HPMC K100 M (X2), and concentration of EC (X3) were selected as independent variables. The time required for 50% drug released (t50), the time required for 80% drug release (t80), similarity factor f2, and mean dissolution time (MDT) were selected as dependent variables. The results of full factorial design indicate that the HPMC K4M (X1), Concentration of HPMC K100 M (X2), and concentration of EC (X3) have a significant effect on in vitro drug release profile. To find out the release mechanism the in vitro release data were fitted in the Korsmeyer-Peppas equation. All Batches except F1 and F3 show Anomalous diffusion-controlled release (combined mechanism of diffusion and case II transport).