الفهرس 
General IntroductionOnly 14 pages are availabe for public view
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Abstract
A variety of drugs are characterized by a narrow absorption window in the upper gastrointestinal tract or preferred to be localized in the stomach for their local action.
Gastroretentive dosage forms are able to deliver drugs with narrow absorption window in a controlled manner by releasing the drug for a prolonged period of time.
The ways to achieve gastric retention based on swelling, mucoadhesive, hydrogel, floating or high-density systems.
Floating dosage forms are low density single or multi-unit systems that have sufficient buoyancy to float over the gastric contents providing continuously drug release at the desired rate.
Raft forming system is a type of gastroretentive system in which sodium alginate solution containing carbonates or bicarbonates ,when comes in contact with gastric fluid ,swells and forms a viscous cohesive gel containing entrapped CO2 bubbles, which forms a raft layer on the top of gastric fluid .
The nanoparticles are ultrafine particles in the size of nanometer order. Nanoparticles frequently show behavior which is intermediate between that of a macroscopic solid and that of an atomic or molecular system. A nanosuspension platform is an efficient and intelligent drug delivery system for water-insoluble drugs because these platforms increase the saturation solubility and the surface area available for dissolution.
This work is divided into 2 parts:
Part one: Ranitidine hydrochloride melt granulated floating microparticulates: preparation and in-vitro evaluation:
The purpose of the present part is to develop floating gastroretentive ranitidine microparticulates using lipid based formulation and study the effect of a group of additives on drug release.
Fourteen microparticulates formulae containing 336 mg ranitidine hydrochloride were prepared by simple melt granulation method using 3 types of lipid base (Compritol ATO 888, Cutina HR, Cutina GMS) and different types of additives (Aerosil 200, PVP K90, ethylcellulose).
The prepared microparticulates formulations were evaluated by investigating the physical properties (Particle size using sieve analysis, Bulk density, and tapped density, angle of repose, compressibility index, scanning electron microscopy and in vitro buoyancy test) and the chemical analysis (drug content and drug release).