Page 58 - controlled drug delievery
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2- Floating systems
– Dosage forms with densities < 1 gm/cm3 will float on the top of gastric
fluids. Sufficient fluids must be present in the stomach to support these
systems.
2-A- Hydrodynamically balanced systems (HBS)
– Single unit DF, contain one or more gel forming hydrophilic polymers e.g.
HPMC, NaCMC & alginic acid.
Drug diffusion through
the surface hydrogel
barrier
Gastric fluid
Hydration and Further hydration &
swelling of erosion of the gel
surface barrier
polymer
Gel mass density < 1 gm/cm3
