7 FORMULATION AND EVALUATION OF SUSTAINED RELEASE FLOATING TABLETS OF LORATADINE

Loratadine a long-acting tri-cyclic antihistamine with selective peripheral histamine H1-receptor antagonistic activity, is used for the symptomatic relief of allergic conditions like runny nose, itchy or watery eyes, sneezing and nasal or throat itching and chronic urticaria. It is stable in acidic pH, has a narrow therapeutic absorption window in the GI tract and found to be absorbed at proximal part of small intestine. Thus it is decided to prolong the gastric residence time in terms of making floating gastro retentive drug delivery system to increase drug absorption and hence bioavailability. In this study Loratadine floating tablets were prepared by using HPMC K15 M and Sodium Alginate as polymers and gas generating agents like sodium bicarbonate and calcium carbonate at varying polymer concentrations and combinations. The tablets prepared by direct compression technique were evaluated in terms of their pre-compression parameters and post compression characteristics such as physical characteristics, total buoyancy, buoyancy lag time, swelling index and in vitro release. The best formulation showed no significant change in physical appearance, drug content, total buoyancy time, buoyancy lag time or in vitro release after storage at 40 degrees C /75% RH for three months. The in vitro release studies confirmed that the formulation (F10) containing 3:4 % w/w of HPMC K15 M and sodium alginate showed sustained drug release (78.51%) for 12 h and remained buoyant for more than 12 h. Loratadine floating tablets prepared using HPMC and Sodium Alginate polymers adopting direct compression technology found to be very economical mean of improving bioavailability.