FORMULATION AND EVALUATION OF GASTRO-RETENTIVE FLOATING BILAYER TABLETS OF FAMOTIDINE FOR THE TREATMENT OF HYPERTENSION

The aim of present investigation was to formulate and evaluate bilayer gastro retentive tablet of Famotidine. The floating system is intended to float in and over the gastric contents resulting in prolonged GRT. It is very difficult to release loading dose of drug from matrix of tablet within specified period of time, to overcome this difficulty bi-layer tablet of famotidine was prepared. In which one layer was made up of immediate release layer to provide loading dose of famotidine. Loading dose of famotidine released within 30 minutes due to action of super disintegrating agents. Another layer was made up of gastroretentive layer or sustained release layer to provide maintenance dose of famotidine, this layer released drug till 24 hrs due to floating mechanism of HPMC polymer. So there is need to develop a formulation which increase the gastric retention of famotidine so that it slowly available in the stomach and gives the maximum use of famotidine. Initially quantitative estimation of famotidine in formulation was carried out by UV/Visible spectrophotometry using 0.1 N HCl (pH-1.2) as solvent and measuring the absorbance at 266 nm. In phosphate buffer 7.4 pH observed λ max was found to be 286nm. Compatibility studies of drug with excipients were performed under different storage condition for one month. Drug excipient were mixed and divided in five parts, sealed in vials and kept under different temperature conditions. The control sample containing only drugs were sealed in vials and kept as such in low temperature conditions. After one month the sample were withdrawn and observed that there was no change observed in the physical characteristics of the drugs. This shows that there is no incompatibility between drug and excipient used. Physical mixture of drug and polymer was also used for the compatibility study and the samples were analyzed in IR spectrophotometer. For immediate release layer, it was found that all the batches gives release of more than 85 % of drug with in 30 minutes due to the high solubility of famotidine. For sustained release second layer, the use of hydrophilic polymer matrix is one of the most popular approaches in formulating an extended-release dosage form Formulation F1 was found to have lower erosion compared to F3 because HPMC K 100 M has higher viscosity as compared to HPMC K 15 M. It was concluded that HPMC K 100 M gave least erosion. Hence HPMC K 100 M is superior over the other it was selected for formulation. Gas generating agent increased swelling as well as erosion of polymers due to burst effect. Effect of channeling agent, Lactose is used as diluent as well as channeling agent in the floating delivery of the drug. To find out the mechanism of drug released from all the formulations of Famotidine floating tablets, the data was fitted to zero order, first order, Higuchi square root law and Korsmeyer’s equation. Bi-layer tablet releases loading dose within 30 minutes and maintenances dose release till 24 hrs due to good floating & bio adhesive ability. To find out the mechanism of drug release from bilayer tablet, the data were subjected to kinetic modeling. Drug released from bi-layer tablet suggests that drug releases via diffusion mechanism. Thus, the Bi-layer gastro retentive tablet of famotidine can be successfully formulated with HPMC K 100 M and super disintegrating agent povidone. Keywords: Superdisintegrants, fillers, disintegration, drug release, dosing frequency