Gastroretentive Drug Delivery system

Gastro retentive Drug Delivery system, Floating drug delivery

1. Gastro-retentive Drug
Delivery System (GRDDS)

2. GastroretentiveDrug Delivery System
•It is novel drug delivery systems having prolonged retaining ability in
the stomach increasing gastric residence time of drugs and improves
bioavailability of drugs

3. Physiology of Stomach
•The gastric motility pattern is systematized in cycles.
•The duration of each cycle is 90–120 min and it
contains four phases
Phase Description Duration
(min)
Phase I
(basal phase)
Idle state without any
contraction
30 to 60
Phase II
(pre-burst phase)
Intermittent contraction20 to 40
Phase III
(burst phase)
The regular contraction
at the maximal frequency
causes the good material
to migrate distally.
10 to 20
Phase IV Transition period
between
phase III and phase I
0 to 5

4. Approaches of GRDDS
•Bioadhesivesystems,
•Floating systems (low density systems),
•Non-floating systems (high density systems),
•Magnetic systems,
•Swelling systems,
•Unfoldableand expandable systems,
•Raft forming systems and super-porous systems,
•Biodegradable hydrogel systems

5. Rationale of GRDDS

6. Advantages
1.Increase in bioavailability and curative efficiency
of drugs and economic usage of dosage.
2.Minimized factor of risk in resistance in
antibiotics.
3.Reduced dosage frequency of short half life
drugs.
4.Provides with a systematic and controlled drug
delivery
5.Provide both local and systemic effect
6.Improved patient compliance
8. Increase in bioavailability drugs that metabolized
in the upper GIT
9. Minimize the fluctuation of drug concentrations
and effects.
10. Prolong and sustain release of drugs from
dosage.
11. Reduces undesirable effects of side effects.

7. Disadvantages of GRDDS
•Need for increased level of fluids in the stomach.
•Unsuitable for drug with Poor solubility in gastric fluid & drugs Causing G.I irritation
•Undesirable for drugs unstable in acidic environment
•Unsuitable for Drugs intended for selective release in the colon.
•The ability of the drug to remain in the stomach depends upon the subject being
positioned upright.
•Hydrogel based swelling system takes longer time to swell.
•Upon multiple administrations, size increasing drug delivery systems pose the threat to
life owing to possible hazard of permanent retention in stomach.

8. Criteria for selection of drug for GRDDS
1.Drugs those are locally active in the stomach (e.g. misroprostol, antacids)
2.Drugs that have narrow absorption window in GIT (e.g. L-DOPA,
paminobenzoicacid, furosemide, riboflavin).
3.Drugs exhibit low solubility at high pH values (e.g. diazepam,
chlordiazepoxide, verapamil).
4.Drugs that disturb normal colonic microbes such as tetracycline,
clarithromycin, amoxicillin
5.Drugs those are unstable in the intestinal or colonic environment

9. Factors Affecting Gastric Retention of Dosage Forms
•Density, size and shape of the dosage form,
•Food intake and its nature, caloric content and frequency of intake,
•Posture,
•Gender,
•Age, sex, sleep, bodymass index, physical activity
•Diseased states of the individual.
•Administration of drugs with impact on gastrointestinal transit time.

10. Approaches for Gastro-retentive Systems
Gastro-retentive drug delivery system based on
high density.
Gastro-retentive drug delivery system based on
polymer swelling.

11. Gastro-retentive drug delivery system based on
application of magnetic force.
Gastro-retentive drug delivery system based on
combination of polymer swelling and effervescence.

12. Gastro-retentive drug delivery system based
on muco-adhesion.
Gastro-retentive drug delivery system based
on low desnity( Floating system)

13. Mechanisms of the various GRDDS

15. Polymers used in GRDDS
Mucoadhesive Polymers
Synthetic polymers
•Cellulose derivatives
(methylcellulose, ethylcellulose, Hydroxyl propyl
cellulose, hydroxypropyl methylcellulose, sodium
carboxymethylcellulose.
•Poly (acrylic acid) polymers (carbomers,
polycarbophil).
•Poly (hydroxyl ethyl methyl acrylate).
•Poly (vinyl pyrrolidone).
•(f) Poly (vinyl alcohol).
Natural polymers
(a) Tara gum
(b) Sodium alginate
(c) Karayagum
(d) Guar gum
(e) Xanthan gum
(f) Locust bean gum.
Non-EervescentFloating Systems
•HPMC,
•hydroxypropyl cellulose
•hydroxyethylcellulose,
•Sodium
carboxymethylcellulose,
carrageenan,
•agar, and alginicacid
Raft system
•Sodium alginate
•Sodium bi-carbonates
High Density System
•barium sulfate
•zinc oxide,
•iron powder,
•titanium dioxide
Expandable System
•HPMC,
•polyethylene oxide
•Carbopol
Effervescent Floating
•sodium bicarbonate
•calcium carbonate
•tartaric acid, and citric
acid

16. Evaluation of GRDDS (Invivo)

17. In-vivo Evaluation
Diagnostic imaging techniques
•Gamma scintigraphy,
•Radiology,
•Gastroscopy,
•Ultrasonography,
•Magnetic resonance imaging (MRI)
•These techniques determine the location and extent of GRDDS and their transit
through the GIT and preclinical evaluation of GRT, disintegration rate,
dimensions of the dosage form, and esophageal transit of GRDDS