Design and In Vitro Characterization of Controlled Delivery of Simvastatin Using Dual-Mechanism Gastroretentive Floating System

Abstract

Background: Simvastatin is a commonly used lipid-lowering agent with a major formulation challenge
due to its poor aqueous solubility, which could affect its ability to dissolve and become available for
oral absorption. Aim: The present study aimed to design and evaluate a dual-mechanism gastroretentive
floating tablet system of Simvastatin using hydrophilic polymers and a gas-generating agent for controlled
drug delivery. Methods: Six formulations (F1–F6) were prepared by varying polymer concentrations and
formulation composition. The prepared tablets were evaluated for pre-compression properties, physical
characteristics, hardness, friability, drug content, floating lag time, total floating time, swelling behavior,
in-vitro drug release, and release kinetics. Fourier-transform infrared spectroscopy (FTIR) was performed
to assess drug–excipient compatibility. Results: FTIR analysis demonstrated the characteristic bands of
Simvastatin without significant spectral changes, indicating compatibility with the selected excipients.
Among the formulations, F5 showed the most favorable performance, with a floating lag time of 2.5 ±
0.2 min, total floating duration of 12 h, swelling index of 124.7%, and 80.6% drug release after 12 h. The
Korsmeyer–Peppas model provided the best fit, with a release exponent (n) of 0.75, indicating anomalous
drug transport. Conclusion: The findings demonstrated that the combination of polymeric swelling and
gas-generated buoyancy could provide sustained gastric retention and controlled delivery of Simvastatin.