A REVIEW ON GASTRO RETENTIVE DRUG DELIVERY SYSTEM SUBMITTED BY MO SUHEB ANSARI Assistant Professor Department of Pharmaceutics Faculty of pharmacy Jahangirabad Institute of Technology Barabanki, Lucknow, Uttar Pradesh

1. A REVIEW ON GASTRO RETENTIVE DRUG
DELIVERY SYSTEM
SUBMITTED BY
MO SUHEB ANSARI
Assistant Professor
Department of Pharmaceutics
Faculty of pharmacy
Jahangirabad Institute of Technology Barabanki, Lucknow, Uttar Pradesh
1

2. CONTENTS
 INTRODUCTION
 ANATOMY AND PHYSIOLOGY OF THE STOMACH
 GRDDS Vs CONVENTIONAL DDS
 FACTORS AFFECTING GASTRIC RETENTION TIME
 NEED OF GRDDS
 ADVANTAGES
 DISADVANTAGES
 POTENTIAL DRUG CANDIDATES FOR GRDDS
 STRATEGIES FOR DELAYING DRUG TRANSIT THROUGH GIT
 EVALUATION PARAMETERS OF GASTRO RETENTIVE DOSAGE FORM:
 FUTURE PERSPECTIVES OF GRDDS
 CONCLUSION
 REFERENCES
2

3. INTRODUCTION
 Oral administration remains popular despite continuous improvement in drug delivery
approaches Due to patient comfort and ease of administration.
 Dosage forms that can be retained in the stomach are called GRDDs. GRDDSs can improve the
controlled delivery of drugs that have an absorption window by continuously releasing the drug
for a prolonged period of time before it reaches its absorption site.
 These drug delivery systems release the drug in a In a predetermined, predictable and controlled
manner. the use of GRDDS include improvements in Patient compliance by reducing dosing
frequency; better therapeutic efficacy Drugs with short half-life, site-specific delivery of drugs;
continuous and controlled release of drugs into the stomach; increased residence time of the drug
at the absorption site; Better bioavailability from the gastrointestinal tract; Avoid dumping the
dosage of drugs.
 To develop GRDDS are used various materials such as ion-exchange resins, mucoadhesives,
high-Density materials, rafters substances (raft forming), magnetic materials, and super-porous
hydrogel.
3

4. GRDDS ARE BENEFICIAL FOR SUCH DRUGS BY
IMPROVING THEIR-
Bioavailability .
Therapeutic efficacy .
Possible reduction of the dose.
Maintenance of constant therapeutic levels over a Prolonged period and
thus reduction in fluctuation in the therapeutic levels .
Reduce drug wastage.
Improves solubility of drugs that are less soluble at High pH environment
(e.g. weakly basic drug like Domperidone,papaverine).
4

5. ANATOMY AND PHYSIOLOGY OF STOMACH
 The Knowledge of abdominal anatomy and
physiology is essential to be successful
formulation of gastro-retentive dosage forms.
Anatomically, the abdomen is divided into three
Area; The proximal part towards the esophagus
is the fundus, followed by the body, which
Serves as a storage site for the encased food, and
the antrum, the last part that connects them
Body to the small intestine. Antrum helps in
Churning action as well as in Gastric emptying.
5

6. In the fasting state, a sequence of
contractions occurs cyclically
through the stomach and the
intestine every 120-180 minutes,
called the migrating myoelectric
cycle (MMC). It’s ahead Divided
into four phases. The change in the
pattern of contractions in the
condensed state is called Digestive
motility pattern.
6
Ph of the GIT
Stomach 1-3
Small intestine 5-7.5
Large intestine 7.9-8
Rectum 7.5-8

7.  Phase I (basal stage) lasts 30–60 min with rare
contractions.
 Phase II (pre-burst phase) often lasts 20–40 min with
action potentials and contractions. As the phase increases,
the intensity and frequency and frequency gradually
increase .
 Phase III (burst phase) lasts 10–20 min. It involves
short-term severe and frequent contractions. This wave
touches everything from the stomach to the small
intestine. This is also known as the housekeeper wave.
 Phase IV lasts from 0-5 minutes and takes place
between two cycles of Phase III and I, respectively.
7

8. CONVENTIONAL VS GRDDS
8
CONVENTIONAL DDS GRDDS
Toxicity High risk Low risk
Drug acting locally in the stomach Not much advantage Very much advantages
Drug having rapid absorption through
GIT
Not much advantages Very much advantages
Drug with narrow absorption window in
small intestine
Not suitable Suitable
Drugs which are poorly Soluble at an
alkaline pH
Not much advantages Very much advantages
Drugs which are degraded in the colon Not much advantages Very much advantages
Dose dumping High risk No risk
Patient compliance Less More
GRDDS V/S CONVENTIONAL DDD:

9. FACTORS AFFECTING GASTRIC RETENTION TO TIME OF
DOSAGE FORMS
DENSITY
The Dosage forms Can float
if density is less than gastric
contents to the surface, while
high-density systems sink to
the bottom of stomach and
density <1.0 gm/cm3
Required to exhibit the
temporal property of dosage
form.
SIZE AND SHAPE OF
DOSAGE FORM
Dosage form having diameter
of more than 7.5mm have
more gastric residence time
than that of 9.9mm diameter
dosage form. The large size of
the dosage form will not allow
Pass quickly through the
pyloric antrum Intestine.
Some devices such as ring-
shaped and Tetrahedron-
shaped devices have better
gastric Residence time
compared to other shapes.
FED OR UNFED STATE
Under fasting conditions, the
GI Motility is characterized by
periods of strong motar
Activity that occurs every 1.5-2
hrs. The MMC Sweeps
undigested material from the
stomach and if The timing of
the formulation coincides with
that of MMC, the GRT of the
unit can be very short, However
in fast state MMC is delayed
and GRT is Longer.
9

10. CONT…
NATURE OF MEAL
feeding of indigestible
polymers or Fatty acids
can change the motility
pattern of the Stomach to
a fed state, thus
decreasing gastric
Emptying rate and
prolonging drug release.
CALORIC CONTENT
GRT can be increased by
4-10 with A meal that is
high in protein and fat.
AGE
In the case of Older
people with age more than
70 have a significant
Longer GRT.
GENDER
The gastric emptying time is
more in male as compared to
female. mean ambulatory GRT
in male (3.4hrs) is Less
compared with the age and race
matched female Counterparts
(4.6hrs) regardless of height,
weight and Body surface.
10

11. REGULATION OF GASTRIC SECRETION AND
MOTILITY
The Control two neural and hormonal systems Secretion of gastric juice
with contraction of Smooth muscles in the abdominal wall. Events in
the gastric secretion occurs in three overlapping phases; cephalic
Phase, gastric phase and intestinal phase.
CEPHALIC PHASE
 This phase refers to impact on the brain on secretion. It Just before
entering the food in to Stomach.
11

12. GASTRIC PHASE
 The secretion is maintained by the presence
of Food in stomach. It is managed by
hormones Gastrin which are produced in the
mucosa of the pyloric region of stomach.
Gastrin is released in response to Stretching
of the antrum due to the presence of food in
this region or respons to specific substance
presence in the food, specially proteins,
alcohol and coffee are also Stimulation of
gastrin release.
INTESTINAL PHASE
 The material present in the duodenum of
the small intestine is Very acidic, a
hormone released by the intestinal
Mucosa. This hormone is carried by the
blood to the body of the stomach where
it prevents the further acid Secretion. It
acts as a protective device for the small
Intestine that is not even protected from
acid like stomach.
12

13. NEED of GRDDS
Some drugs are absorbed and released On specific sites or a release
such as maximum amount of the drug reaches the specific site. The
pharmaceutical sector is focusing on drugs that Site-specificity is
required.
 Conventional oral delivery is widely used in pharmaceutical field to
treat diseases. However, conventional delivery had many drawbacks
and major draw-back is non-site specificity.
13

14. ADVANTAGES OF GRDDS
 Enhance release in case of short half-life drugs, causes flip flop pharmacokinetics And also ensures
patient compliance with reduced dosage Frequency.
 They are advantageous against drawbacks of the gastric retention time (GRT) as well as the gastric
emptying time (GET). The system remains resilient on Gastric fluid because of lower bulk density than
gastric Fluids.
 These are efficient in repairing the stomach and Small intestine related problems. It applies to the fact
that Gastro retentive drug delivery sustains drug release and Hence, benefits in local therapy in these
organs.
 This Method provides a systematic and controlled drug Delivery system which decreases the chances of
drug Overexposure at the diseased site.
14

15. DISADVANTAGES OF GRDDS
 Hydro gel-based Swelling system takes a long time to swell. Upon Multiple administrations,
size increasing drug delivery Systems pose the threat to life owing to the possible Hazard of
permanent retention in the stomach.
 Super Porous systems having drawbacks like problematical Storage of much easily
hydrolysable, biodegradable Polymers.
 Unsuitable for drugs with limited acid solubility. E.g. Phenytoin.
 Unsuitable for drugs those are unstable in acidic Environment. E.g. Erythromycin.
 Drugs that irritates or causes gastric lesions on slow Release. E.g. Aspirin &NSAID’s.
 Drugs that absorb selectively in colon E.g. Corticosteroid
15

16. POTENTIAL DRUG CANDIDATES FOR GRDDS
 Drugs that act locally in the stomach, such as antacids and misoprostol.
 Drugs that degrade in the colon, such as ranitidine HCl and Metronidazole.
 Drugs that disturb common colonic bacteria, for example, amoxicillin Trihydrate.
 Low-density form of the dosage form that causes buoyancy in gastric fluid.
 High-density dosage form that remains intact in the bottom of the stomach.
 Bioadhesion to abdominal mucosa.
 Slow motility of the GIT by concomitant administration of drugs or Excipients.
 Inflammation or spread of a larger size that limits dosage form emptying through the pyloric
sphincter.
16

17. STRATEGIES FOR DELAYING DRUG TRANSIT
THROUGH GIT
PHARMACEUTICAL
APPROACH
• First two approaches are
not used due to toxicity
problems. The various
pharmaceutical approaches
are-
PHARMACOLOGICAL
APPROACH
• It involves the co-
administration or
incorporation of a drug Into
the dosage form. This drug
delays gastrointestinal
Emptying. Examples
include antimuscarinics,
e.g. Propantheline.
PHYSIOLOGICAL
APPROACH
• It is the use of natural
materials or fat derivatives
such as Triethanolamine
myristate, which stimulate
the duodenal or Jejunal
receptors to slow gastric
emptying
17

18. 18

19. [A] FLOATING OR LOW-DENSITY SYSTEM
 This approach to increase gastric residence is to lower the density of dosage form than the normal
gastric content. These systems remain buoyant due to lower density and provide continuous drug
release. In this way, they increase the gastric retention time of the drug and improves its
bioavailability. Floating system are classified as:
 [a]Non effervescent
 [b]Effervescent
[a] NON-EFFERVESCENT GRDDS
 Non-stimulating GRDDS is based on the mechanism of swelling of Polymer or bioadhesion to the
mucosal layer in the GIT such as polycarbonate, polyacrylate, Polymethacrylate, polystyrene,
chitosan and carbopol. They are further classified as:
19

20. 1. HYDRO DYNAMICALLY BALANCED SYSTEMS (HBS)
 In this system is designed to extend the stay of
dosage form in the gastric-intestinal tract and
aids in enhancing Absorption.
 Drug with good dispersion in acidic
Environment and having specific site of
absorption in the upper part of the small
intestine is achieved by HBS system.
 In the stomach for a prolonged period of time
The dosage form must have a bulk density of
less than ‘1’ and Must maintain its structural
integrity and release the drug constantly dosage
form.
20

21. 2. LAYERED TABLETS
[a] SINGLE LAYER FLOATING TABLETS
 They are formulated by intimate mixing of
drug with gel-forming hydrocolloid, which
swells in contact with gastric fluid and
maintain bulk density of less than unity.
 The air trapped by the swollen polymer
confers buoyancy to these dosage forms.
They are plan by Intimate mixing of drugs
with low-density enteric Materials like CAP,
HPMC.
[b] BI-LAYER FLOATING MATRIX TABLETS
 A bi-layer tablet Means two-layer one is
prompt release layer which is released
Initial dose from system while another is
sustained release layer absorbs gastric
fluid, forming a dense colloidal gel
obstruction on its surface, and maintain
bulk density of Less than unity and thereby
it remains buoyant in stomach.
21
• Layered tablets are more popular due to their ease of preparation, low cost, and high
stability.

22. 3. ALGINATE BEADS MULTI-UNIT FLOATING DOSAGE
FORMS
It formulated from freeze-dried calcium alginate. the spherical
beads with approx 2.5mm diameter can be prepared by dropping
sodium alginate solution in an aqueous Solution of calcium chloride,
causing precipitation of calcium Alginate.
 The alginate is then separated from the beads and solidified in liquid
nitrogen. And freeze-dried – 40 ° for 24 hours, which leads to the
formation of a porous System which can maintain floating power
above 12 hours.
22

23. 4. HOLLOW MICROSPHERE
 Hollow Microsphere (Micro Balloons), weighted
with the drug in their outer polymer shells are
prepared by a novel emulsion-solvent diffusion
method. Ethanol: dichloromethane solution Drug
and an enteric acrylic polymer in was poured into
agitated by Aqueous solution of PVA that is
thermally controlled 40 degree Celsius.
 Gas-phase formed in the diffuse polymer droplet
Evaporation of dichloromethane forms an internal
The cavity in the microsphere of the polymer with
the drug. The Micro balloons often float on the
surface of acedic Dissolution media containing
surfactant for over 12 Hours in vitro.
23

24. [b] EFFERVESCENT SYSTEM
 Effervescent System contains the use of Gas generating agents carbonates (eg
sodium bicarbonate) and others Organic acids (such as citric acid and tartaric acid)
are present in the system to producing carbon dioxide (CO2) gas thus Reduce the
density of the system and making it float on Gastric fluid. A different Is the
incorporation of a matrix containing a portion of liquid, which produces gas that
evaporate at body temperature.
 This Effervescent System is further classified into two types
(1) Gas generating systems
(2) Volatile Liquid/Vacuum Containing Systems
24

25. 1. GAS GENERATING SYSTEMS (TABLETS FLOATING
BILAYER)
 Preparing a solid dispersion with Is mixed in the ratio of 1:1. One
layer consists of polymers HPMC K4M, HPMC K100M, and CMC
(for extent) and drug. Second layer enclosed the mixture of
sodium bicarbonate And citric acid.
 The in vitro floating studies that the lesser the compression force,
the shorter the time onset of floating, i.e., when the tablet were
compressed At 15 MPa, these can float in 20 minutes Whereas the
at a force of 32 MPa, the time was increased to 45 minutes.
 Study on 6 Healthy male Volunteers showed that the floating
tablet was retained in stomach for 6 hours and further blood analysis
studies Showed that the bioavailability of these tablets was 1.8
times Which is regular tablet.
[a] FLOATING CAPSULES
 It is Prepared by stuffing
with A mixture of
sodium alginate and
sodium bicarbonate.
During in vitro tests the
system was shown to
float because a the result
of the generation of CO2
which was captured in
Hydrating Gel Network
on Exposure to an Acidic
environment.
25

26. [b] MULTIPLE UNIT TYPES FLOATING PILLS
 The System contains Sustained-release pills as
a ‘seed’ surrounded by double Layers. Inner
layer made of Effervescent agents Whereas the
outer layer is of the swellable membrane layer.
 When the system is an evince in the
dissolution medium at Body temperature, it
drops at once and then forms expand pills Like
balloons, which float as they have lower
density. This lower density is due to generation
and bait of CO2 Within the system.
26

27. [c] ION-EXCHANGE RESINS
 A Floating system using ion exchange resin that was packed
with bicarbonate by Mixing the beads with 1M sodium
bicarbonate solution.
 The Packed pellets were then Surrounded by a
semipermeable membrane to escape Sudden loss of CO2.
Gastric contents contain the chloride and bicarbonate ions
combine to form CO2 engendering there By carring beads
towords the top of gastric contents and produce a floating
layer of resin beads.
 In vivo nature of coated and Uncoated pellets were observed
using the single channel Analyzing studies in 12 healthy
human volunteers by Gamma radio scintigraphy. Studies
have shown that Gastric residence time was significantly
increased (24 Hours) compared to uncoated beads (1 to 3
hours).
27

28. [2] VOLATILE LIQUID / VACUUM CONTAINING
SYSTEMS
 In this system its for gathered to float in the stomach Due to the flotation
chamber, which can be a vacuum or filled with air while the drugstore is
encapsulated inside a micro-porous.
 [a] INFLATABLE GASTROINTESTINAL DELIVERY SYSTEMS
 [b] INTRAGASTRIC OSMOTICALLY CONTROLLED DRUG DELIVERY SYSTEM
28

29. [a] INFLATABLE GASTROINTESTINAL DELIVERY
SYSTEMS
 Liquid ether is present in the inflatable chamber which
gasifies at body temperature to cause the chamber to
inflate in the stomach.
 The Inflatable Chamber with a drug reservoir, Which
can be a drug impregnated polymer matrix, Enclosed in
gelatin capsules. after oral conduct, the capsule
dissolves to release the Drug Reservoir together With
inflatable chamber.
 The Inflatable Chamber No doubt inflate and retains
the drug reservoir Compartment in the stomach. the
drug continuously released from the reservoir into the
Gastric fluid.
29

30. [b] INTRAGASTRIC OSMOTICALLY CONTROLLED
DRUG DELIVERY SYSTEM
 The Intragastric osmotic pressure controlled drug delivery
system consists of two components; a drug Reservoir
compartment and an osmotically active Compartment.
Drug Reservoir enclosed by Pressure responsive
collapsible bag, which is Impermeable to vapor and liquid
and have a drug delivery orifice. the osmotically effective
compartment An osmotically active salt and enclosed
within Semi-permeable housing.
 In the stomach, there is gastric fluid Engaged through a
semipermeable membrane into the osmotically active
compartment to dissolve the Osmotically active salt. The
osmotic pressure builds acts On the collapsible bag and in
turn, forces the drug Reservoir compartment to reduce its
volume and activate Drug release through the delivery
orifice.
30

31. [B] BIO ADHESIVE DRUG DELIVERY SYSTEM
 When the polymer system interacts with the mucus layer, it
Known as muco adhesion. An oral bio adhesive System, it is
important to through understanding of mucosa., bio-adhesive
polymers and mucin-polymers Interactions in the physiological
environment.
 Intestinal mucosa is unaware of the high molecular weight
Glycoproteins are hydrated and cover the mucosa with
Continuous adherent blanket. mucin glycoproteins are Rich
in fucose and sialic acid groups at the fetal ends which imparts
a net negative charge in acidic environment. The density of the
mucin gel layer varies in different Region of GIT With the
thickness ranging Between 50-500μm in the stomach to 15-
150μm in the Colon. The consistency of mucin gel depends on
Glycoprotein concentration.
31

32. [C] RAFT FORMING SYSTEMS
 Rafts Floatation have been used in the treatment of Gastric
Esophageal reflux disease (GERDS). It Have received much
awareness For the delivery of antacids and drug delivery for
Gastrointestinal infections and disorders.
 The mechanism Used in the raft formation includes the
formation of Viscous cohesive gel in contact with gastric fluids,
Wherein each part of the liquid swells forming a Continuous
layer called a raft.
 An antacid raft setup floating System contains a gel forming
agent (e.g. sodium Alginate), sodium bicarbonate and acid
counter, which Forms a foaming sodium alginate gel (raft),
which when Comes in contact with gastric fluids, the raft floats
on the Gastric fluids and prevents the reflux of the gastric
Contents into the esophagus by acting as a barricade Between the
stomach and esophagus
32

33. [D] SWELLABLE / EXPANDABLE SYSTEM
 In this system When enters to stomach, swells up (due
to the presence of Swellable polymers) to an extent that
cannot pass through the Pyloric sphincter leading to
retain in the stomach for a Long time refererd as the
“plug type system” Because they tends to remain lodged
at the pyloric sphincter.
 Thus, requires three arrangements: oral Intake
swallowed in a small configuration. Expanded to a size
that obstructs their passage through the pylorus. Finally,
after the drug is released at a predetermined time, it Gets
ready for an evacuation since the device is no longer can
attain or retain the expanded configuration.
33

34. [E] MAGNETIC SYSTEM
 This system is based on the simple idea that the
dosage form Contains a small internal magnet, and a
magnet placed on the Abdomen over the position of
the stomach. Using a Extracorporeal magnet, gastric
residence time of the dosage Form can be enhanced
for a prolonged period of time .
 The real applicability of Such systems are
questionable because the desired result Can be
obtained only if the position of the magnet is Selected
with very high precision.
34

35. [F] HIGH DENSITY (SINKING) SYSTEM
 Dosage formulation Form with a density that must be
greater than the density of Normal stomach contents
(~1.004 g/cm3 ) . The system is fabricated by coating the
drug on a heavy Elemental or mixed with inert substances
such as iron Powder, Barium Sulfate, Zinc Oxide and
Titanium Oxide .
 The Density rises by upto 1.5- 2.4 gm/cm3 . A density
closed to 2.5 gm/cm3 Seems paramount for Significant
prolongation of gastric residence time. But, The
effectiveness of this system in humans was not observed
and no system has been marketed.
35

36. [G] SUPERPOROUS HYDROGELS
 Superporous hydrogels are a 3-dimensional network of hydrophilic
polymers that have numerous super-size pores inside them. The swelling
of superporous hydrogels occurs by the mechanism of capillary wetting
through interconnected open pores.
 To formulate superporous hydrogels, certain ingredients like initiators
and cross-linkers are used to initiate the cross-linking. Other ingredients
involved are foam stabilizers, foaming aids, and foaming agents.
 A superporous hydrogel system using N', N'- methylene bisacrylamide
(BIS) as the crosslinking operator and polyvinyl alcohol as a composite
specialist, ammonium persulfate and N, N-tetra methylene diamine as an
initiator pair and span 80 as a surfactant. They are used as a froth
stabilizer to make a permeable structure by the gas-forming method.
36

37. EVALUATION PARAMETERS OF GASTRO RETENTIVE
DOSAGE FORM
[1] BUOYANCY LAG TIME
 It is the time taken by gastroretentive
formulations to come onto the surface of the
dissolution medium. It is determined using USP
dissolution apparatus containing 900ml of 0.1 N
HCl solution as a testing medium maintained at
370 C. The time required to float different
dosage forms noted as floating lag time.
[2] FLOATING TIME
 It determines the buoyancy of dosage form. In
this test, a specific dissolution apparatus is used
depending upon the type of dosage form with
900ml of dissolution medium kept at 37 C. The
floating time or floating duration of the dosage
form is determined by visual observation.
37
IN-VITRO ASSESSMENT:
For gastroretentive drug delivery systems, in vitro assessment is very essential to predict gastric transit behavior.
Following are the parameters which should be considered for designing novel gastroretentive formulations.

38. CONT…
[3] SPECIFIC GRAVITY
/ DENSITY
• Specific gravity
estimates are essential
for both low-density
and high-density
GRDDS. Specific
gravity is determined
using the Displacement
method.
[4] SWELLING INDEX
• The swelling index is
determined by
immersing the tablets in
0.1 N HCl at 37 C and
their periodic removal at
regular intervals.
[5] WATER UPTAKE
• In this study, the dosage is
form removed out from the
dissolution medium after the
regular interval and a weight
change is determined.
Water uptake (WU) = (Wt
– Wo) * 100 / Wo
Where Wt = weight of the
dosage form at time t,
Wo = initial weight of
dosage form.
38

39. CONT…
[6]WEIGHT VARIATION
• Various official methods
are recommended by
pharmacopeias that
calculate the weight
variation. Usually, the
individual and average
weight of 20 tablets is
recorded. From this
data, average weight
and weight variation are
calculated.
[7] HARDNESS &
FRIABILITY
• Hardness or crushing
strength is
determined using
Monsanto tester,
Strong cobb tester,
Pfizer tester, etc.
Friability (Strength)
of tablets is
determined using
Roche friabilator.
[8]IN-VITRO
DISSOLUTION TESTS
• This test is performed to
determine drug release
from GRDDS in gastric
fluid and intestinal fluid
maintained at 37 C at a
definite time using USP
dissolution type II
apparatus (paddle).
39

40. IN-VIVO ASSESSMENT
[1] RADIOLOGY
• This technique is mainly used
to determine the position of
gastroretentive dosage form
filled with barium sulfate
(radio-opaque marker) inside
the body system concerning
time using Xray. X-ray
pictures are taken at different
intervals to record the correct
position of the dosage form.
[2] SCINTIGRAPHY
• Similar to radiology, it is
used to determine the in
vivo floating behavior of
the gastroretentive
dosage form. In
scintigraphy, 99mTc
pertechnetate is used as
an emitting material
instead of an X-ray to
engulf the formulation to
record the image.
[3] GASTROSCOPY
• Gastroscopy is used
widely for visual
examination of
gastroretentive dosage
form. In this technique,
an illuminate optical,
tubular, and slender
instrument called an
endoscope is used to look
deep inside the body parts
such as the stomach,
esophagus, and small
intestine.
40

41. CONT…
[4]ULTRASONO
GRAPHY
• It is a diagnostic
imaging
technique in
which ultrasound
is used for
imaging internal
body structures.
The main
disadvantage of
this test is non-
detectability at
entrails.
[5] 13C OCTANOIC
ACID BREATH
• Test Radioactive 13C
Octanoic acid is used to
assess the extent of
absorption of drugs from
GRDDS. This compound
gets absorbed from the
duodenum, and when it is
radiolabelled, then after its
metabolism, the CO2
exhaled in breath can be
correlated to the amount of
octanoic acid absorbed. The
radiolabelled CO2 is
measured by isotope ratio
mass spectroscopy.
[6] MAGNETIC MARKER
MONITORING
• As compared with radiology and
scintigraphy, this method is radiation-less
and thus is nonhazardous. It involves real-
time tracking of the dosage form in the
gastrointestinal tract. This technique is
mainly used for the determination of the
gastrointestinal motility and dissolution
behavior of pharmaceuticals. In this
technique, the dosage form is labeled as a
magnetic dipole by incorporating a trace of
ferromagnetic particles and recording the
magnetic dipole field by an apparatus
responsive to bio-magnetic measurement.
41

42. FUTURE PERSPECTIVES OF GRDDS
 The GRT of the conventional dosage form is one of the main challenges in the pharmaceutical
industry, especially for drugs that are absorbed from the upper part of the intestine.
Developing GRDDS will help to overcome the drawbacks associated with conventional
dosage form, although further work is needed on its shortcomings. To date, many studies have
been performed on GRDDS utilizing the single system approach such as floating, expandable,
and mucoadhesive systems. Even though various GRDDS technologies have been extensively
explored to achieve successful gastroretentive systems, most have their own limitations .
 The variation in GRT, especially in the fed and fasted states, is still one of the main challenges
faced by many formulation scientists. No single approach might be the best for resolving the
problems. Therefore, it is desirable to explore suitable GRDDS that can overcome the
limitations of a single approach.
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43. CONT…
 Moreover, dual-working systems are less affected by the physiological condition of the stomach such as
the fasting and fed states and these systems can ensure delayed gastric emptying. Therefore, future works
on GRDDS should be focused on combinations of different mechanisms in order to prolong gastric
retention of dosage forms even in the fasted state.
 It is essential to assess gastroretentive dosage forms on a case-by-case basis because the physiochemical
nature of drug and excipients, types and composition of polymers, drug dose, and manufacturability may
depend on product specification Another important aspect for improving GRDDS is to understand the
effects of formulation and process variables on the critical quality attributes of GRDDS. The critical
quality attributes of GRDDS include floating behavior, floating force, gel strength, mucoadhesive
strength, mucoadhesive time, in vitro drug release, swelling capacity, porosity of hydrogel, tablet tensile
strength, and friability. From formulation viewpoints, understanding polymer behavior and its role in
formulation is crucial for the rational development of the gastroretentive dosage form. Furthermore,
selection of an appropriate concentration of polymer is equally important for designing such dosage
forms.
43

44. CONT…
 In this regard, the quality by design (QbD) approach can be a useful tool for investigating the influence
of formulation and process variables on the critical quality attributes of GRDDS. With implementation
of the QbD approach in pharmaceutical fields, there has been a significant transformation in the
understanding and control of the manufacturing process, which notably minimizes the risk of product
failure .
 Some gastroretentive approaches such as magnetic systems have not been extensively studied. The
clinical studies of these systems have not yet been reported in detail. Therefore, future works on
magnetic systems need to be focused on clinical candidates to specify their practical applications in
humans. Moreover, incorporating magnetic systems into the superporous hydrogel system can help
extracorporeal magnets precisely locate the ingested dosage form since it swells and occupies larger
volume. The advancement of technologies offers efficient measurement tools that can help to predict
and correlate the gastric emptying time and passage of drug into the GIT. For example radiology and
scintigraphy can be used for the in vivo evaluation of gastric emptying of dosage forms from the
stomach . Moreover, magnetic marker monitoring techniques can also be utilized to capture images of
dosage forms in the stomach.
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45. CONCLUSION
Gastro retentive drug delivery system has emerged as an Efficient
means of prolonged retaining ability in the Stomach and thereby
increase gastric residence time of Drugs and improves bioavailability of
drugs. Despite Number of difficulties to be worked out to achieve
Prolonged gastric retention, many companies are Focusing towards
commercializing this technique. Number of commercial products and
patents issued in This field are evident of it.
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