Gastroretentive drug delivery system of metoclopramide hydrochloride: formulation and in vitro evaluation.

The present investigation concerns the development of floating matrix tablets of metoclopramide hydrochloride (MHCl) for improving its bioavailability by prolonging gastric residence time. Floating matrix tablets (FMT) of MHCl were prepared using the polymers guar gum (GG), karaya gum (KG), HPMC E15 (HE) alone and in combination with HPMC K15M (HK) and gas generating agents such as calcium carbonate and citric acid. The fabricated tablets were evaluated for their physical characteristics such as hardness, drug content, buoyancy, swelling properties and in vitro release studies in 0.1N HCl. The tablets without gas generating agents and HK did not float at all whereas tablets with gas generating agents and without HK floated for 2.33-5.48 h then eroded completely and exhibited faster drug release. Tablets with gas generating agents and HK floated for 24 h without complete erosion and showed slower drug release. This indicates that gas generating agents contributes towards the initial floating of tablets and faster drug release and HK for maintaining the integrity of the FMT and sustaining the drug release. The increase in the concentration of HK in FMT from 10 mg to 40 mg resulted in decrease in release rate of drug. The possibility of drug polymer interaction was determined by differential scanning calorimetry (DSC) and fourier transform infrared (FTIR) spectrometer, and confirmed no interaction between drug and polymers. The release pattern of prepared tablets followed Higuchi kinetics which confirms release mechanism by diffusion.