Journal of Pharmacy Research Vol.1.Issue 1. July-September 2008 Optimization and In Vitro Evaluation of Floating Tablets of Atenolol Vijay Daulatrao Havaldar 1 *, Ajit Shankarrao Kulkarni 1 , Remeth Jacky Dias 1 , Kailas Krishnat Mali. 1 1 Satara College of Pharmacy, Plot.No.1539, New Additional M.I.D.C, Degaon, Satara, 415004, M.S. India For correspondance. Vijay Daulatrao Havaldar, Satara College of Pharmacy, Plot.No.1539, New Additional M.I.D.C, Degaon, Satara, M.S. India PIN 415004 E mail: vdh2006@rediffmail.com Received on: 10-06-2008; Accepted on :14-07-2008 ABSTRACT: The main aim of this study was to optimize and evaluate the floating tablets of atenolol that prolongs the gastric residence time. Semisynthetic polymers, HPMC K4M, HPMC K100M and natural polymer, Xanthan gum were used as release retarding agents. Sodium bicarbonate was used as a gas-generating agent. Dicalcium phosphate was used as a channeling agent. The floating matrix tablets of Atenolol were prepared by direct compression method. The concentration of polymers and a gas-generating agent was optimized to get the controlled release of atenolol for 8h. The prepared tablets were evaluated for physicochemical parameters and found to be within range. A significant difference in drug release at 0.5, 1, 4 and 8 h ( p < 0.0001) was observed. The floating lag time of all the formulations was within the prescribed limit (< 10 min.) Release pattern of Atenolol was fitted to different models based on coefficient of correlation (R). All the formulations showed good matrix integrity. All the formulations retarded the release of drug for 8 h. Based on the diffusion exponent (n) value, drug release was found to be diffusion controlled. The swelling studies of all the formulations showed that formulations containing Xanthan gum has higher swelling indices than HPMC K100M and HPMC K4M. Further it was observed that the formulations, which are having higher swelling indices, retarded the release of drugs than those having low swelling indices. Key words : Floating, Atenolol, Swelling index, HPMC. INTRODUCTION: Several techniques are used to design gastro retentive dosage forms. These include floating; swelling; inflation; adhesion; high-density systems and low density systems that increase the gastric residence time 1, 2, 3. Gastric retention is useful for those drugs which (i) act locally; (ii) have a narrow absorption window in the small intestinal region; (iii) unstable in the intestinal environment; and (iv) low solubility at high pH environment 4. Vari- ous dosage forms have been developed for gastric re- tention; these include, floating tablets 5; floating beads 6; pellets 7; floating granules8; and floating microspheres 9. In this investigation, an attempt was made to design floating tablets of Atenolol by using different release retarding polymers along with a gas-generating agent. Atenolol is a beta 1 cardio selective adrenergic receptor blocker, widely used in the treatment of hy- pertension. The drug is insoluble in water and has half- life of 6 to 8 h with oral bioavailability of 50% due to smaller dose of drug (less than 50mg) 10, 11. In the present study, an attempt was made to optimize the concentration of natural and semi synthetic polymers for the controlled release of drug and to evaluate the tablets for physicochemical parameters. HPMC K4M, HPMC K100M and Xanthan gum were used as a release re- tarding agents for Atenolol. Sodium bicarbonate was used as a gas generating agent and dicalcium phosphate (DCP) was used as a channeling agent. The release pattern and swelling indices of all the formulations were analyzed using different mathematical models 12. MATERIALS AND METHODS: Materials: Atenolol was procured from Flamingo Pharma- 73 Research Article