Abstract
A multiple-unit floating drug delivery system based on gas formation technique was developed, in order to prolong the gastric residence time and to increase the overall bioavailability of the dosage form. The floating bead formulations were prepared by dispersing nevirapine together with calcium carbonate in a mixture of sodium alginate and hydroxypropyl methylcellulose solution and then dripping the dispersion into an acidified solution of calcium chloride. Calcium alginate beads were formed, as the alginate underwent ionotropic gelation by calcium ions, and carbon dioxide developed from the reaction of carbonate salts with acid. The obtained beads were able to float due to CO2-gas formation and the gas entrapment by the polymeric membrane. The prepared beads were evaluated for percent drug loading, drug entrapment efficiency, morphology, surface topography, buoyancy, in-vitro release, and release kinetics. The formulations were optimized for different weight ratios of the gas-forming agent and sodium alginate. The beads containing higher amounts of calcium carbonate demonstrated an instantaneous, complete, and excellent floating ability over a period of 24 hours. The increased amount of the gas forming agent did not affect the time to float, but increased the drug release from the floating beads, while increasing the coating level of the gas-entrapped membrane, increased the time to float, and slightly retarded the drug release. Good floating properties and sustained drug release were achieved. Finally, these floating beads seemed to be a promising gastroretentive drug delivery system.
Highlights
Drug absorption from a gastrointestinal tract (GI) is a complex procedure and is subjected to many variables.[1]
The process and ability to prolong and control the emptying time is a valuable asset for dosage forms, which reside in the stomach for a longer period of time than the conventional dosage forms,[3] such as, tablets, capsules, and granules
These physiological problems have been overcome by several drug delivery systems, by investigating the prolonged gastric retention time.[4,5]
Summary
Drug absorption from a gastrointestinal tract (GI) is a complex procedure and is subjected to many variables.[1] These variables make the in-vitro performance of the drug delivery systems uncertain.[2] The process and ability to prolong and control the emptying time is a valuable asset for dosage forms, which reside in the stomach for a longer period of time than the conventional dosage forms,[3] such as, tablets, capsules, and granules. The mechanism of action is that it binds directly to the human immunodeficiency virus type I (HIV-I) RT, an RNA-dependent DNA polymerase, blocking its function in viral DNA replication
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