Presented by:Maryam albuloshi

B.Pharm

CONTENTSIntroductionBasic GIT physiologyProcess of gastric emptyingMechanism of FDDSApproaches for prolonging the gastric residence timeClassificationIMPORTANCE OF FDDSFactor affecting Floating timeAdvantage of FDDSDisadvantage of FDDSEvaluation testsExamplesConclusionReference

1

INTRODUCTION Floating drug delivery systems is known as hydrodynamically controlled

systems.

It is having low bulk density that have sufficiently buoyancy to float over the gastric contents and remain buoyant (floating) in the Gastric juice of stomach without affecting the gastric emptying rate for a prolonged period of time.

This leads to an increased gastric retention time (GRT) and a better control of the fluctuations in plasma drug concentration.

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BASIC GIT PHYSIOLOGY

• Reservoir for ingested material.

fundus• Reservoir for ingested material.

body• Major site of mixing motion.• Acting as pump to propel gastric

contents for gastric emptying.pylorus

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PROCESS OF GASTRIC EMPTYING

Gastric emptying occurs in both fasting and fed states.

Fasting state Interdigestive

series of electric event take place.

It cycles both through stomach

and intestine every 2-3 hrs

It called as interdigestive

myoelectric cycle

Its having 4 phasesPhase 1Phase 2Phase 3Phase 4

ingestion of a mixed meal

fed state (digestive motility

pattern) 4

•last from 30-60 minutes with rare contractions.

Phase 1-(Basic phase)

•last for 20-40 minutes with intermittent action potential and contractions.

Phase 2-(Preburst

phase)

•last for 10-20 minutes which includes intense and regular contractions for short period.

Phase 3-(Burst phase)

•last for 0-5 minutes and occurs between phase 2 and 1 of 2 consecutive cycles.

Phase 4

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Mechanism of FDDS• FDDS has a bulk density less

than gastric fluids and so remain buoyant in the stomach with out affecting the gastric emptying rate for a prolonged period of time.

F = F buoyancy - F gravity = (Df - Ds) gv

Where, F= total vertical force, Df = fluid density,

Ds = object density, v = volume and

g = acceleration due to gravity.

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APPROACHES FOR PROLONGING THE GASTRIC RESIDENCE TIME

HIGH-DENSITY SYSTEMS. (HDS)

FLOATING SYSTEMS. (FS)

SWELLING AND EXPANDING SYSTEMS. (SS)

MUCOADHESIVE & BIOADHESIVE SYSTEMS. (AS)

HDS

FS

SS

A S8

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Floating Drug Delivery System

Effervescent System

Gas generating system

Volatile liquid/ vacuum

containing system

Non-Effervescent System

Single Layer Floati

ng Tablet

Bilayer

Floating

Tablet

Alginate

Beads

Hollow/

floating

Microspher

es

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Non effervescent systems

• Prepared from one or more gel forming or highly swellable cellulose type hydrocolloids (e.g. hydroxyl ethyl cellulose, hydroxypropyl methyl cellulose [HPMC] etc ) or polysaccharides, or matrix forming polymers(e.g polyacrylates, and polystyrene) are incorporated in high level (20 75% ‐w/w) to tablets or capsules.

• Gel forming hydrocolloid swells in contact with gastric fluid after oral administration and maintain a relative integrity of shape and bulk density of less than unity within gastric environment.

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Non Effervescent SystemSingle Layer Floating Tablet or

hydrodynamically balanced system

Bilayer Floating Tablet

Alginate Beads

Hollow Microspheres/ Microballoons

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HYDRODYNAMICALLY BALANCED SYSYTEMS:

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Bilayered Floating Tablets

These are compressed tablet as containing two layer1-Immediate release layer 2-Sustained release layer.

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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.

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HALLOW MICROSPHERES

1. Hallow microspheres as one of the most promising buoyant systems, as they possess unique advantages of multiple unit systems as well as better floating properties, because of central hallow spaces inside the

microsphere.2. The general techniques involved in their preparation include simple

solvent evaporation, and solvent diffusion and evaporation.

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Effervescent system

• These are matrix type of systems with the help of swellable polymers such as methycellulose and chitosan and various effervescent eg, sodium bicarbonate, tartaric acid and citric acid.

• They are formulated in such a way that when in contact with the acidic gas content ,CO2 is liberated and gets entrapped in swollen hydrocolloids, which provides buoyancy to the dosage form.

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1. Gas Generating System

Intra gastric single layer floating tablet

Intra gastric bilayer floating tablet

Multiple unit floating pills

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2. Volatile liquid /vacuum containing SystemIntra gastric floating GIDDS

Inflatable GIDDS

Intra gastric osmotically CDDS

Factor affecting Floating time

1• Effect of Dosage Form Size&

Shape

2 • Gender, Posture & Age

3 • Effect of Food & Specific Gravity

4 • Type of Formulation

5 • Nature of Meal & Frequency of Food 19

IMPORTANCE OF FDDS

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Advantages of FDDS

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

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Disadvantage of FDDS

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.

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EVALUATION TESTS

IN-VITRO TEST IN-VIVO TEST

•Floating lag time•Floating time

•Dissolution study•Resultant weight test

•X ray method•Gamma-scintigraphy

•Gastroscopy•Ultra sonography

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Marketed Products of GRDDSBrand name Delivery system Drug (dose) Company

name

Valrelease® Floating capsule Diazepam (15mg) Hoffmann-LaRoche,USA

Madopar® HBS(Prolopa® HBS)

Floating, CR capsule Benserazide (25mg) and L-dopa (100mg)

Roche Products, USA

Liquid Gaviscon® Effervescent Floating liquid alginate preparations

Al hydroxide (95 mg), MgCarbonate (358 mg)

GlaxoSmithkline,India

Topalkan® Floating liquid alginatePreparation

Al – Mg antacid Pierre Fabre Drug,France

Conviron® Colloidal gel forming FDDS

Ferrous sulphate Ranbaxy, India

Cytotech® Bilayer floating capsule Misoprostol (100μg/200μg) Pharmacia, USA

Cifran OD® Gas-generating floating form

Ciprofloxacin (1gm) Ranbaxy, India

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Widely used drug and dosage forms

S .No Dosage

FormDrugs

1. MICROSPHERE Aspirin, Griseofulvin, p-nitroglycerine, ibuprofen, Terfinadine, Tranilast.

2. GRANULES Diclofenac sodium, Indomethacin, Prednisolone

3. FILMS Cinnarizine

4. CAPSULE Chlrdiazepoxide, Diazepam, Furosemide, L-Dopa, Benserazide, Misoprostol, Propanolol

5. TABLET/ PILLS Acetaminophen, ASA, Amoxicilin Trihydrate,Ampicilin, Atenolol, Chlorphenarimine,Cinnazirine, Diltiazem,Flourouracil, Isosorbide Mononitrate & dinitrate, p-aminobenzoic acid, Prednisolone, Quinidine Gluconate,Ribiflavin 5-p, Sotalol,Theophylline, Verapamil

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CONCLUSION:

floating drug delivery systems have an efficient means of enhancing the bioavailability and controlled delivery of many drugs.

Dosage forms with a prolonged GRT will bring about new and important therapeutic options

The currently available polymer-mediated Non effervescent and effervescent FDDS, designed on the basis of delayed gastric emptying and buoyancy principles, appear to be a very much effective approach to the modulation of controlled oral drug delivery.

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REFERENCE

• Controlled drug delivery system concept and advance ,by S.R.VYAS,196-215

• International Journal of Pharmaceutical Research & Allied Sciences, Volume 1, issue 4 (2012),20-28

• Journal of Current Pharmaceutical Research 2011 ;7 (1): 6-20 • Pharmacophore International Research Journal 2013, Vol. 4

(1), 26-38

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