Gastroretentive Bilayer film for sustained release of atorvastatin calcium and immediate release of amlodipine besylate: Pharmaceutical, Pharmacokinetic evaluation, and IVIVC.

The present study was aimed to optimize capsulated unfolding type gastroretentive bilayer film constituting immediate release (IR) layer of amlodipine besylate and sustained release (SR) layer of atorvastatin calcium. A three-factor, three-level Box-Behnken-design was used to optimize bilayer film with dual-release characteristics. The selected independent variables were HPMC-K3, Eudragit RSPO, and Carbopol 934P and the responses were floating duration, swelling index, and in vitro release from SR layer in 8 h. The films were also assessed for pharmacotechnical characteristics, release kinetics, DSC, FTIR, and SEM. The pharmacokinetics of the drugs from the optimized formulation was compared with the marketed formulation in rabbits. The capsulated accordion film unfolded and provided SR of atorvastatin for 8 h (96.76% +/- 0.71) and IR of amlodipine within 25 min (98.07% +/- 0.62) for the optimized formulation (F14). The swelling index and floating duration for the optimized formulation were 140.48 +/- 0.57 and 8.53 +/- 0.10 h, respectively. Results of pharmacokinetics showed that faster absorption of amlodipine and improved bioavailability (2.16-fold) of atorvastatin in blood was made available through bilayer film. In vitro-in vivo correlation was established using numerical deconvolution method. It can be concluded that the capsulated gastroretentive system provided site specific simultaneous SR of antihyperlidemic drug and IR of antihypertensive drug as single pill that has therapeutic potential to manage cardiovascular risk.