formulation and evaluation

1. METHOD OF FORMULATION
AND ITS EVALUATION OF
GASTRO-RETENTIVE DRUG
DELIVERY SYSTEM
PREPARED BY :- SURYANSH SINGH
M. PHARM FIRST YEAR
GUIDED BY :- F.R. SHEEBA
DEPT. :- PHARMACEUTICS
MALLIGE COLLEGE OF PHARMACY

2. CONTENTS
INTRODUCTION
Anatomy of
stomach
Formulation
approaches
Evaluation

3. • INTRODUCTION:
• CDDS are those convenient means of drug delivery
systems which are meant to obtain a reduction of daily
administration of drugs with fast absorption and
elimination. Many controlled release systems have been
developed for maintaining a therapeutically effective
concentration of drug in systemic circulation for longer
period of time as well as to reduce side effects.

4. Anatomy of stomach

5. Formulation approaches
Floating Drug
Delivery
Systems
(FDDS)
Swelling and
expanding
systems,
Bio-adhesive
Systems and
Modified
shaped
systems,
High
density
systems.

6. Floating systems
The system which have bulk density lower
then the gastric content is called Floating
drug delivery system.
They have the potential for continuous
release of drug and remain buoyant in the
stomach for a prolonged period of time.

7. CLASSIFICATION OF FLOATING
SYSTEM
A) Effervescent Floating tablets:-
These are matrix types of systems prepared with
the help of swellable polymers such as
methylcellulose and chitosan and various
effervescent compounds, eg, sodium bicarbonate,
tartaric acid, and citric acid. They are formulated in
such a way that when in contact with the acidic
gastric contents, CO2 is liberated and gets
entrapped in swollen hydrocolloids, which
provides buoyancy to the dosage forms

8. • Non-Effervescent Floating tablets:-
Non-effervescent floating tablets use a gel forming or swellable cellulose type of
hydrocolloids, polysaccharides, and matrix-forming polymers like polycarbonate,
polyacrylate, polymethacrylate, and polystyrene.
The formulation method includes a simple approach of thoroughly mixing the
drug and the gel-forming hydrocolloid. After oral administration this dosage
form swells in contact with gastric fluids and attains a bulk density of < 1.
The air entrapped within the swollen matrix imparts buoyancy to the dosage
form. The so formed swollen gel-like structure acts as a reservoir and allows
sustained release of drug through the gelatinous mass.
•

9. Bilayer Floating Tablets:-
This system basically contained two layers an
immediate release layer and sustained release layer.
Immediate release layer release the initial dose
immediately and sustained layer forms colloidal gel
barrier by absorbing gastric fluid and thereby it
maintain density of less than one and remain floating
in stomach.

10. RAFT forming system:-
Systems consists of some gel forming agents. Eg- Sodium
alginate solution containing carbonate or bicarbonate.
These systems produce a layer on the top of the gastric fluids

11. Methods of Developing
Floating Drug Delivery Systems
Direct Compression Technique
Effervescent Technique
Wet Granulation Technique
Ionotropic Gelation Technique
Solvent Evaporation Technique
Spray Drying Technique
Melt Solidification Technique
Melt Granulation Technique

12. Direct Compression Technique:- It involves compressing tablets
directly from powder material without modifying the physical nature of material itself.
example- tricalcium phosphate
Effervescent Technique:- The floating chamber of the drug
delivery system can be filled with inert gas (CO2) by the effervescent reaction
between organic acid (citric acid) and bicarbonate salts.
Wet Granulation Technique:- It employs a solution suspension or slurry
containing a binder which is usually added to the powder mixture however the binder
may be incorporated into the dry powder mix and the liquid may be added by itself.

13. Ionotropic Gelation Technique:- Gelation of anionic
polysaccharide sodium alginate, the primary polymer of natural origin, was achieved with
oppositely charged calcium ions (counter-ions) with an aim to form instantaneous
microparticles
Solvent Evaporation Technique:- The capacity of the continuous
phase is insufficient to dissolve the entire volume of disperse phase solvent. Solvent
evaporates from the surface of the dispersion to obtain hardened microspheres
Spray Drying Technique:- It involves dispersing the core material in a
liquefied coating material and spraying the core coating mixture into the environment to
effect solidification of coating. Solidification is accomplished by rapid evaporation of the
solvent in which coating material is solubilised.

14. Melt Solidification Technique:- This process involves emulsification
of the molten mass in the aqueous phase followed by its solidification by chilling. The
carriers used for this technique are lipids, waxes, polyethylene glycol, etc
Melt Granulation Technique:- It is a process by which the
pharmaceutical powders are agglomerated by using a meltable binder and no water or
organic solvents are required for granulation. There is no drying step, the process is time
consuming and uses less energy.
Granules are prepared in a lab scale high shear mixture using a jacket
temperature of 600C and an impeller speed of 20,000 rpm.

15. Bio-adhesives :- In these systems the dosage form will stick to the
mucosal surface in the gastrointestinal tract as a result of which prolonged
gastric retention can be achieved
. The various bioadhesive polymers are :- polybrene, polylysine, dextran
sodium etc.
Expendable systems:- It is small enough to swallowed. After coming into contact
with the gastric fluids, they get expended to a larger size so that gastric retention is achieved
High density system: - Normal stomach contents have density 1gm/ml. these dosage
forms have density more than gastric content (3gm/cm3) , thus retained in rogue of the
stomach and are capable of withstanding peristaltic movements.
Various materials used for manufacturing of such high density formulation are barium
sulphate, zinc oxide , titanium dioxide, iron powder etc.

16. Evaluation of gastroretentive
drug delivery system
General tests
• Hardness • Friability •
Weight variation • Content
uniformity • Dissolution •
Drug release
Buoyancy time
• Buoyancy lag time
• Buoyancy duration
Swelling studies
• %Swelling index= Wo-(Wi+Wo)͟͟͟͟͟͟͟͟͟͟͟͟͟͟͟͟/Wi×100
• Where, Wo= wt. of swollen tablet with
OHP sheet • Wi= Wt. of initail tablet •
Wb= Wt. of OHP paper

17. IN-VIVO EVALUATION -
a) Radiology
X-ray is widely used for examination of internal body systems.. Barium Sulphate is widely used Radio Opaque Marker. So,
BaSO4 is incorporated inside dosage form and X-ray images are taken at various intervals to view GR.
b) Gastroscopy :-
Gastroscopy is peroral endoscopy used with fiber optics or video systems. Gastroscopy is used to inspect visually the effect of
prolongation in stomach. It can also give the detailed evaluation of GRDDS.
c) Magnetic Marker Monitoring:-
In this technique, dosage form is magnetically marked with incorporating iron powder inside, and images can be taken by
very sensitive biomagnetic measurement equipment. Advantage of this method is that it is radiation less and so not hazardous

18. REFERENCES:
• Horoshi S, Yasuhiko M, Toshio O, Masaharu M and Hisakazu S: Dissolution
mechanism of diclofenac sodium from wax matrix granules. J Pharm Sci. 1997;
86: 929-932.
• Sangekar S, Vadino WA, Chaudry I, Parr A, Beihn R and Digenis G: Evaluation of
effect of food and specific gravity of tablets on gastric retention time. Int J Pharm.
1987; 35: 187-191.
• Hilton AK, Desay PB: In vitro and in vivo evaluation of an oral sustained release
dosage form of amoxycilline trihydrate. Int J Pharm. 1992; 86: 79-88.
• Atyab F, Sharma HL, Mohammad HAH, Fell JT: In vivo evaluation of a novel gastric
retentive formulation based on ion exchange resins. J Control Release. 1996; 42:
105-108.
• Longer MA, Ching HS, Robinson JR: Bioadhesive polymers as platforms for oral
controlled drug delivery-III: Oral delivery of chlorothiazide using a bioadhesive
polymer. J Pharm Sci. 1985; 74: 406-411.

19. Thank you