Gastro Retentive Drug Delivery system is a Novel drug delivery system which is more used to retain the drug for a longer period of time in the body and also to increase the GI transit time.

1. GRDDS- AN INNOVATIVE AND NOVEL DDS
PREPARED AND PRESENTED BY-
PROF. VEDANSHU R. MALVIYA
P.R.POTE PATIL COLLEGE OF PHARMACY
(Approved by AICTE, PCI-New Delhi & Affiliated to
SGBAU- AMRAVATI)

2. CONTENTS
 Introduction
 Need for GRDDS
 Advantages and Limitations
 Ideal Characteristics for GRDDS
 Types and Approaches of GRDDS
 Marketed Products of GRDDS
 Conclusion
 References

3. INTRODUCTION
 Gastroretentive drug delivery is an approach to
prolong gastric residence time, thereby targeting
site-specific drug release in the upper
gastrointestinal tract (GIT) for local or systemic
effects
 Gastro-retentive delivery is one of the site
specific delivery of the drugs at stomach. It is
obtained by retaining dosage form into stomach
and drug is being released at sustained manner
to specific site either in stomach or intestine.

4. NEED FOR GRDDS
 Conventional oral drug delivery system (DDS) is
complicated by limited gastric residence time (GRT).
 Rapid GI transit can prevent complete drug release in
absorption zone & reduce the efficacy of the
administered dose since the majority of drugs are
absorbed in stomach or the upper part of small intestine.
 To overcome these limitations, various approaches have
been proposed to increase gastric residence of drug
delivery systems in the upper part of GIT includes
gastro retentive drug delivery system (GRDDS).

5. ADVANTAGES
 Enhanced bioavailability
 Sustained drug delivery/reduced frequency of dosing
 Targeted therapy for local ailments in the upper GIT
 Reduced fluctuations of drug concentration
 Improved selectivity in receptor activation
 Reduced counter-activity of the body
 Extended effective concentration.
 Minimized adverse activity at the colon

6. LIMITATIONS
 The drug substances that are unstable in the acidic
environment of the stomach are not suitable candidates
to be incorporated in the systems.
 These systems require a high level of fluid in the
stomach for drug delivery to float and work efficiently.
 Not suitable for drugs that have solubility or stability
problem in GIT.
 Drugs which are irritant to gastric mucosa are also not
suitable.
 These systems do not offer significant advantages over
the conventional dosage forms for drugs, which are
absorbed throughout GIT.

7. IDEAL CANDIDATES OF DRUG FOR GRDDS
 Drugs acting locally in the stomach.
E.g. Antacids and drugs for H. Pylori viz., Misoprostol.
 Drugs that are primarily absorbed in the stomach.
E.g. Amoxicillin
 Drugs that is poorly soluble at alkaline pH.
E.g. Furosemide, Diazepam, Verapamil, etc.
 Drugs with a narrow absorption window.
E.g. Cyclosporine, , Levodopa, Methotrexate etc.
 Drugs which are absorbed rapidly from the GI tract.
E.g. Metronidazole, tetracycline.
 Drugs that degrade in the colon.
E.g. Ranitidine, Metformin.
 Drugs that disturb normal colonic microbes.
E.g. antibiotics against Helicobacter pylori.

8. TYPES AND APPROACHES OF GRDDS

9. HIGH DENSITY SYSTEM
 Gastric contents have a density close to water ( 1.004
g cm−3). When the patient take high-density pellets ,
they sink to the bottom of the stomach where they
become entrapped in the folds of the antrum and
withstand the peristaltic waves of the stomach wall.
 A density close to 2.5 g cm−3 seems necessary for
significant prolongation of gastric residence time.
 Barium sulphate , zinc oxide, iron powder, and titanium
dioxide are examples for excipients used.

10. FLOATING DRUG DELIVERY
 These have a bulk density lower than the gastric content.
They remain buoyant in the stomach for a prolonged
period of time, with the potential for continuous release
of drug. They Include:
 Hydrodynamically balanced systems (HBS)
 Gas-generating systems
 Volatile liquid/ vacuum containing systems
 Raft-forming systems
 Low-density systems

11. GAS GENERATING SYSTEMS
 Carbonates or bicarbonates, which react with gastric
acid or any other acid (e.g., citric or tartaric) present in
the formulation to produce CO2 , are usually
incorporated in the dosage form, thus reducing the
density of the system and making it float on the media.

12. MATRIX TABLETS
 Single layer matrix tablet is prepared by incorporating
bicarbonates in matrix forming hydrocolloid gelling
agent like HPMC, Chitosan, alginate or other polymers
and drug.
 Bilayer tablet can also be prepared by gas generating
matrix in one layer and second layer with drug for its SR
effect.
 Triple layer tablet also prepared having first swell able
floating layer with bicarbonates, second sustained
release layer of drug and third rapid dissolving layer of
bismuth salt.

13. INFLATABLE GASTROINTESTINAL
DELIVERY
 System is incorporated with an inflatable chamber which
contains liquid ether-gasifies at body temperature to
cause the chamber to inflate in stomach.
 Inflatable chamber is loaded with a drug reservoir which
can be a drug, impregnated polymeric then
encapsulated in a gelatin capsule.

14. INTRAGASTRIC OSMOTICALLY
CONTROLLED
 Comprised of both an osmotic pressure controlled drug delivery
device and an inflatable floating support in a biodegradable capsule.
 In stomach, the capsule quickly disintegrates and release the
intragastric osmotically controlled drug delivery device .
 Inflatable support forms a deformable hollow polymeric bag
containing liquid that gasifies at body temperature to inflate the bag.
 Consists of 2 compartments:
1) Drug reservoir
2) Osmotically active compartment

15. INTRA-GASTRIC FLOATING GASTROINTESTINAL
DRUG DELIVERY SYSTEMS
 System can be float by flotation chamber,
which may be vacuum or filled with air or a
harmless gas.
 Drug reservoir is encapsulated inside a micro
porous compartment.

16. HYDRODYNAMICALLY BALANCED
SYSYTEMS
 Prepared by incorporating a high level (20-75%w/w) gel-
forming hydrocolloids. E.g.:- Hydoxyethylcellulose,
Hydroxypropylcellulose, Pullulan, HPMC & Sod. CMC
into the formulation and then compressing these
granules into a tablets or capsules.
 It maintains the bulk density less than 1.

17. RAFT FORMING
 This system is used for delivery of antacids and drug
delivery for treatment of gastrointestinal infections and
disorders.
 The mechanism involved in this system includes the
formation of a viscous cohesive gel in contact with
gastric fluids, forming a continuous layer called raft.

18. HOLLOW MICROSPHERES/
MICROBALLOONS
 Polymers used commonly: Polycarbonates, Cellulose
acetate, Calcium alginate, Eudragit Class,
agar,methoxylated pectin etc.

19. ALGINATE BEADS / SUPERPOROUS
HYDROGELS
ALGINATE BEADS
 Prepared by dropping sodium
alginate solution into aqueous
solution of calcium chloride,
causing the precipitation of
calcium alginate
 Freeze dry in liquid nitrogen at -
40oc for 24h.
 Beads-spherical and 2.5 mm in
diameter.
SUPERPOROUS
HYDROGELS
 Swellable agents have pore size
ranging between 10nm to 10µm.
 Superporous hydrogels will swell
more than the swelling ratio
100,This is achieved by co-
formulation of a hydrophilic
particulate material, and Ac-Di-
Sol (crosscarmellose).

20. EXPANDABLE SYSTEMS
 The swelling is usually results from osmotic absorption
of water.
 The device gradually decreases in volume and rigidity as
a result depletion of drug and expanding agent and/or
bioerosion of polymer layer, enabling its elimination.

21. MUCOADHESIVE SYSTEMS
 The basis of mucoadhesion is that a dosage form can
stick to the mucosal surface by different mechanisms.
 Examples for Materials commonly used for bioadhesion
are poly(acrylic acid) (Carbopol®, polycarbophil),
chitosin, Gantrez® (Polymethyl vinyl ether/maleic
anhydride copolymers), cholestyramine, tragacanth,
sodium alginate, HPMC, Pullulan,etc.

22. MARKETED PRODUCTS OF GRDDS
Brand Name Drug Delivery System Company
Cifran OD ® Ciprofloxacin HCl
(500mg-1000mg)
Gas Generating
Floating System
Sun Pharma, India
Rantac OD ® Ranitidine
(300mg)
Floating System J.B Chemicals,
India
Conviron ® Ferrous sulphate Colloidal gel
forming FDDS
Ranbaxy, India
Dompan SR ® Pantoprazole
(40mg) and
Domperidone
(30mg)
Floating Tablet Medley, India
Creon 10000 ® Pancreatin (10000
units)
Microcapsules Abbot, India
Topalkan® Al – Mg antacid Floating liquid
alginate
Preparation
Pierre Fabre Drug,
France

23. CONCLUSION
 Gastro retentive drug delivery systems has proved to be a
novel approach of controlled delivery of drugs that
exhibit an absorption window.
 All these drug delivery systems have their own
advantages and drawbacks.
 To design a successful GRDDS, it is necessary to take
into consideration the physicochemical properties of the
drug, physiological events in the GIT, formulation
strategies, and correct combination of drug and
excipients.
 From this we can concluded that GRDDS can be a better
alternative than other oral drug delivery system having a
retentive drug delivery system

24. REFERENCES
 S. P. Vyas, Roop K. Khar, CONTROLLED DRUG
DELIVERY – Concepts & Advances, Vallabh Prakashan,
page no. 196-217.
 N K Jain. Gastroretentive drug delivery systems:
Garima Chawla, Piyush Gupta and Aravind K. Bansal,
editors. Progress in controlled and novel drug delivery
systems. New Delhi.
 N. K. Jain, Progress in Controlled & Novel Drug
Delivery Systems, 1st edition 2004, CBS Publishers,
page no.76-97

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