RESUMO
The objective of present study was to develop a gastroretentive drug delivery system of propranolol hydrochloride. The biggest problem in oral drug delivery is low and erratic drug bioavailability. The ability of various polymers to retain the drug when used in different concentrations was investigated. Hydroxypropyl methylcellulose (HPMC) K4 M, HPMC E 15 LV, hydroxypropyl cellulose (HPC; Klucel HF), xanthan gum, and sodium alginate (Keltose) were evaluated for their gel-forming abilities. One of the disadvantages in using propranolol is extensive first pass metabolism of drug and only 25% reaches systemic circulation. The bioavailability of propranolol increases in presence of food. Also, the absorption of various drugs such as propranolol through P-glycoprotein (P-gp) efflux transporter is low and erratic. The density of P-gp increases toward the distal part of the gastrointestinal tract (GIT). Therefore, it was decided to formulate floating tablet of propranolol so that it remains in the upper part of GIT for longer time. They were evaluated for physical properties, in vitro release as well as in vivo behavior. In preliminary trials, tablets formulated with HPC, sodium alginate, and HPMC E 15 LV failed to produce matrix of required strength, whereas formulation containing xanthan gum showed good drug retaining abilities but floating abilities were found to be poor. Finally, floating tablets were formulated with HPMC K4 M and HPC.
