DRUG DELIVERY SYSTEM (gastro retentive drug delivery system) Oral route is the most acceptable route for drug administration. Apart from conventional dosage forms several other forms were developed in order to enhance the drug delivery for prolonged time period and for delivering drug to a particular target site. Gastro-retentive drug delivery system (GRDDS) has gainned immense popularity in the field of oral drug delivery recently. it is a widely employed approach to retain the dosage form in the stomach for an extended period of time and release the drug slowly that can address many challenges associated with conventional oral delivery, including poor bioavailability. different innovative approaches are being applied to fabricate GRDDS. Gastroretentive drug delivery is an approach to prolong gastric residence time, there by targeting site-specific drugs release in the upper gastrointestinal tract (GIT) for local or systemic effects. It is obtained by retaining dosage form into stomach and by releasing the in controlled manner.

1. Institute of Pharmaceutical Education & Research
Borgaon (Meghe), Wardha
Seminar Presentation
Topic:- Gastro-Retentive Drug Delivery Systems
Presented By:- Mr. Rizwan Ahmad Manzoor Ahmad
M. Pharm , Pharmaceutics [Semester 1]

2. Contents
Introduction
Principle
Need of GRDDS
Modulation of GI transit time approaches to extend GI transit
technique.
Advantages & Disadvantage
Evaluation of GRDDS
References

3. Introduction.
 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 efficiency of the administered dose since the
majority of drugs are absorbed in stomach or the upper part of the
small intestine.
 To overcome these limitation, Gastro retentive drug delivery is an
approach to prolong gastric residence time, thereby targeting site
specific drug release in the upper gastrointestinal track(GIT) for
local or systemic effects. GRDDS can remain in the gastric region
for prolong periods and hence significantly prolong the gastric
retention time (GRT)of drug.

4. Principle
 Gastro retentive delivery systems are designed to be
retained in the stomach for a prolonged time and release
their active ingredients and thereby enable sustained and
prolonged input of the drug to the upper part of the
gastrointestinal (GI) tract.

5. Need for GRDDS:
 Drug that are absorbed from the proximal part of the
gastrointestinal tract(GIT).
 Drugs that are less soluble or that degrade at the alkaline pH.
 Drugs that are absorbed due to variable gastric emptying time.
 Local or sustained drug delivery to the stomach
and proximal small intestine to treat certain condition.
 Treatment of peptic ulcers caused by H.pylori infection.

6. Review of Stomach & GIT
 A tube about nine meters long that runs though the middle of the body
from the mouth to the anus and includes;
-throat(pharynx),
-esophagus,
-stomach,
-small intestine
-duodenum
-jenenum
-ileum
-large intestine.

7. Modulation of GI transit time approaches to extend
GI transit techniques.
Low density
system(Floating drug
delivery )
Swellable/Expandable
system
Mucoadhesive
system
High density
system
Effervescent system
Gas generating Volatile liquids

8. Low density system(Floating drug delivery)
 Its retained in stomach.
 Useful for poorly water soluble OR
unstable in intestinal fluid.
 Bulk density: less then gastric fluid so
remain buoyant in the stomach without
affecting gastric emptying rate for
prolong period of time.
 So drug release is slowly at the desired
rate from system.

9. Evaluation of GRDDS
Floating drug delivery system
floating time
• Determination by using the USP dissolution apparatus containing
900ml of 0.1N HCL maintained at 37 c
• The time for at which the dosage form floats is formed as the
floating time.
Specific gravity/Density
• Density can be determined by the displacement method using
benzene as displacement medium.

10. Swellable/Expandable system
 It also called as PLUG SYSTEM.
 A dosage form in the stomach will withstand gastric
transit if it bigger then pyloric spincter ,but should be
small enough to be swallowed.
 These systems swells many time its original size.
 Cross linking should be optimum because highly cross
linked don’t swell properly.
 Sustained and controlled release is achieved by
selection of proper molecular weight polymer and
swelling of polymer regards drug release.
 Chitosan, HPMC ,sodium starch glycolate ,Carbopol
polymers are used.
 Diclofenac, ciprofloxacin, furosemide, are reported with
these system.

11. Picture of tablet in dry and wetted state

12. Evaluation of
Swelling systems
Weight gain and water uptake
• Done by immersing the dosage in simulated gastric fluid at 37 C and determining these
factor at regular intervals.
• Dimensional charges can be measured in the tablet diameter of thickness with time.
• Water uptake is measured in terms of % weight gain.
WU= (Wt-Wo) 100
Wo
Where, WU = water uptake
Wt = weight of dosage form at time t
Wo = weight of dosage form initially

13. Mucoadhesive System
 In this system the drug is incorporated with Muco-adhesive agents, enable the Device
to adhere to the stomach walls thus resisting gastric emptying.
 However the mucus on the walls of the stomach is in a state of constant renewal,
resulting in unpredictable adherence.
 Thus, this approach is not widely used.

14. Evaluation of
Muco-adhesive system
• Measure of either tensile or shear strength is the most commonly
used method to measure bio-adhesion strength.
• Measurement of tensile strength involve quantifying the force
required to break the adhesion bond between the test polymer and
model membrane.
• The method typically uses modified balance or tensile tester.

15. Effervescent system
Gas generating system.
 Carbonates or bi carbonates which react with gastric
acid or any other acid (e.g. citric acid or tartaric acid)
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 in the media.

16. Volatile liquid/ vacuum containing system
 These system contain an inflatable
chamber, which contains a
liquid(ether, cyclopentane),that
gasifies at body temperature to cause
inflation of the chamber in stomach
 These devices are osmotically
controlled floating systems containing
a hollow deformable unit that can
convert from a collapsed to an
expanded position and returns to
collapsed period.

17. High Density system
 Gastric contents have a density close to water. 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 wave of the stomach wall.
 A density close to 2.5gm/cm3 seems necessary for significant
prolongation of gastric residence time.
 Generally Barium sulphate, zinc oxide, iron powder and titanium
dioxide are used as an excipient.

18. Advantages
 Improve drug absorption because of increase GRT.
 Enhanced bioavailability.
 Controlled drug delivery can achieved by this method.
 Reduced dosing frequency due to increase GRT.
 Better patient compliance because no skilled person required to take
it.
 Easy to administered.
 Targeted therapy for local aliments in the upper GIT.
 Reduced fluctuation of drug concentration.

19. Disadvantages
 The drug substances that are unstable in the acidic
environment of the stomach are not suitable
candidates to be incorporated in the system.
 These system required a high level of fluid in the
stomach for the drug delivery to float and work
efficiently.
 Not suitable for drugs which are irritant to the
gastric mucosa.
 These system do not offer significant advantages
over the conventional dosage forms for drugs
which are absorbed throughout GIT.

20. References
 Doshi S.M., Tank H.M., Gastro Retention - An Innovation over Conventional poorly Soluble
Drugs: A review, International Journal of Pharmaceutical and chemcal Sciences, 2012;1(2):859-
866.
 S. P. Vyas, Roop K. Khar, CONTROLLED DRUG DELIVERY - Concepts & Advances, Vallabh
Prakashan, page no. 196-217.
 N. K. Jain, Progress in Controlled & Novel Drug Delivery Systems, 1st edition 2004, CBS
Publishers, page no.76-97
 Chien Yie W. "Novel drug delivery systems", Vol-50, 2nd ed, Marcel Dekker. Inc, New York. Pg
No.164-177.
 Anand S. Surana & Rakhee K. Kotecha, "An overvew on various approaches to oral controlled
drug delivery system via gastroretention" IJPSRR, Vol-2, May June 2010. pp: 68-72
 Ecyclopedia of Pharmaceutical Technology.

21. Thank you