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Hydrodynamic characteristics, such as drop size, dispersed phase hold-up and flooding have been studied experimentally in a pulsed sieve plate extraction column of 0.076 m diameter. Geometrical parameters like perforation diameter, plate spacing and fractional free area (FFA) of sieve plate and operating parameters, such as pulse velocity and superficial velocities of dispersed and continuous phase, were studied using kerosenewater system. The drop size was reduced with decrease in perforation diameter, plate spacing, FFA and pulse velocity. Dispersed phase hold-up was found to be a function of drop size and superficial velocity of dispersed phase. At pulse velocity of 0.025m/s the parabolic behaviour with maxima at the transition from mixer-settler to dispersion regime of flooding curve has been noticed for all the different geometrical conditions. The maximum mass transfer interface together with utmost throughput was obtained at perforation diameter of 0.003 m, plate spacing of 0.05m and FFA of 0.2. The optimal operating parameters were pulse velocity of 0.025 m/s and superficial velocity of 0.006 m/s using organic to aqueous ratio (O/A) of 1:1. The drop size attained at these conditions was 0.0015 m with dispersed phase hold-up of 18%. The correlations developed can be used for the prediction of hold-up and drop size.

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For the treatment of gastrointestinal ulcers, raft forming systems incorporating Nizatidine were developed to provide sustained drug release and prolong gastric residence time. The raft forming formulations contained Nizatidine as a raft forming agent, Isabgol as a gelling polymer and sodium bicarbonate as an agent to generate gas and calcium carbonate as an agent to strengthen gels. Sodium bicarbonate, along with divalent Ca++ ions, forms a floating raft loaded with drugs. Raft formulation was optimized by applying Full Factorial Design of 33. Testing was done on all batches for pH, In-Vitro Floating, Raft strength, Acid Neutralizing capacity, viscosity, and drug release. The majority of formulations using Isabgol as a gelling agent have a gelled raft in less than 2 minutes and are buoyant for more than 8 hours in 0.1N hydrochloric acid having pH 1.2. Optimized batches show good administration capabilities and better stability over six months. The studies conducted suggested that raft forming systems made from natural polymers carrying drugs could be used to deliver gastroretentive drugs.