1. Floating drug delivery systems are aimed to achieve increased bioavailability of drugs by retaining the dosage form in the stomach for a prolonged period of time through buoyancy. This allows for site-specific delivery and absorption of drugs that act in the upper gastrointestinal tract. 2. Floating drug delivery systems can be single or multiple unit systems, and work through effervescent or non-effervescent mechanisms to temporarily reduce the density of the dosage form and allow it to float in the gastric fluids. 3. These systems provide benefits like sustained drug release over extended periods, enhanced absorption of drugs that act in the upper GI tract, and ability to deliver drugs locally for conditions like gastric ulcers. Evaluation

1. 1
FLOATING DRUG DELIVERY SYSTEM
INTRODUCTION
The design of oral control drug delivery systems (DDS) are primarily aimed to achieve more predictable
and increased bioavailability.
This ideal systems have advantage of single dose for the whole duration of treatment and it can deliver the
active drug directly at the specific site. Control release implies the predictability and reproducibility of the
drug concentration in target tissue and optimization of the therapeutic effect of a drug in the body with
lower and less frequent dose.
Floating drug delivery offers several applications for drugs having poor bioavailability because of the
narrow absorption window in the upper part of the gastrointestinal tract. It retains the dosage form at the
site of absorption and thus enhances the bioavailability.
GASTRO RETENTIVE DRUG DELIVERY SYSTEM
The relatively brief gastric emptying time (GET) in humans which normally averages 2-3 hrs through the
major absorption zone i.e., stomach and upper part of the intestine can result in incomplete drug release
from the drug delivery system, leading to reduced efficacy of the administered dose. This has led to the
development of oral gastroretentive dosage forms.
Gastroretention is essential for (1) drugs that are absorbed from the stomach, (2) drugs that are poorly
soluble or degraded by the higher pH of intestine, (3) drugs with an absorption which can be modified by
changes in gastric emptying time. (4) Gastroretentive dosage forms are also useful for local as well as
sustained drug delivery for certain conditions, like H. pylori infection which is the cause of peptic ulcers.
This dosage form improves bioavailability, therapeutic efficacy and may even also allow a possible
reduction in the dose because of steady therapeutic levels of drug.
GRDDS

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CONVENTIONAL Va/S GASTRORETENTIVE DRUG DELIVERY SYSTEM
APPROACHES TO GASTRIC RETENTION
 High density approach
 Low density approach
MECHANISM OF ACTION
These delivery systems utilize effervescent reactions between carbonate/bicarbonate salts and citric/tartaric
acid to liberate CO2, which gets entrapped in the gellified hydrocolloid layer of the systems thus
decreasing its specific gravity and making it to float over GI fluid.

3. 3
CLASSIFICATION OF FDDS
 Single unit floating dosage system
Effervescent system
Non - effervescent system
 Multiple unit floating dosage
system
Effervescent system
Non – effervescent system
Hollow microspheres
 Raft forming system
Single Unit Floating Dosage System
Effervescent system
This systems generate gas (CO2) thus reduce the density of the system, and remain buoyant in
the stomach for a prolonged period of time and release the drug slowly at a desired rate.
Composed of effervescent layers and swell-able membrane layers coated on sustained release pills.

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Non effervescent system
This systems commonly use gel forming or highly swell-able cellulose type hydro-colloids,
polysaccharides and matrix forming polymers, such as polycarbonate, polyacrylate, polymethacrylate and
poly styrene.
Multiple unit floating system
Effervescent system
This dosage forms may be an attractive alternate since they have been shown to reduce inter and
intra subject variability in drug absorption as well as to lower the possibility of dose dumping.
Non effervescent system
A multiple unit FDS containing indomethacin as a model drug prepared by extrusion process is
reported.
Hollow microspheres
Both natural and synthetic polymers have been used to prepare floating microspheres.

5. 5
Raft forming system
This systems have received much attention for the drug delivery for GI infections and disorders.
APPLICATIONS OF FDDS
Sustained drug delivery :
HBS (Hydrodynamic balance systems) can remain in the stomach for long periods and hence can release
the drug over a prolonged period of time. The problem of short gastric residence time encountered with an
oral formulation can be overcome with these systems.
Site specific drug delivery:
These systems are particularly advantageous for drugs that are specifically absorbed from stomach or the
proximal part of the small intestine.
Absorption Enhancement:
Drugs that have poor bioavailability because of site-specific absorption from the upper part of the
gastrointestinal tract are potential candidates to be formulated as floating drug delivery systems, thereby
maximizing their absorption.
ADVANTAGES
SUSTAINED DRUG DELIVERY:
As mentioned earlier drug absorption from oral control release (CR) dosage forms is often limited by the
short gastro retention time (GRT) available for absorption.
These special dosage forms are light, relatively large in size, and do not easily pass through pylorus.
SITE SPECIFIC DRUG DELIVERY:
A floating dosage form is a feasible approach especially for drugs which have limited absorption sites in
upper small intestine.
The controlled, slow delivery of drug to the stomach provides sufficient local therapeutic levels and limits
the systemic exposure to the drug.
This reduces side effects that are caused by the drug in the blood circulation.
PHARMACOKINETIC ADVANTAGES
Drugs that have poor bioavailability because their absorption is limited to upper GI tract can be delivered
efficiently thereby maximizing their absorption and improving their absolute bio-availabilities.
Floating dosage forms with SR characteristics can also be expected to reduce the variability in transit
performance.

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LIMITATIONS
Floating systems are not feasible for those drugs that have solubility or stability problems in gastric fluid.
They require a sufficiently high level of fluids in the stomach for the drug delivery, to float there in and to
work efficiently.
EVALUATION OF FDDS
 Floating duration
 Dissolution profiles
 Specific gravity
 Content uniformity
 Differential scanning calorimetry
 Particle size analysis
 Flow properties
Examples of drugs formulated as different forms of FDDS
Monitor
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