Transcript CONTROLLED RELEASE ORAL DRUG DELIVERY SYSYTEMS

Controlled drug delivery is one which delivers the
drug at a predetermined rate, for locally or
systemically, for a specified period of time.
Plasma concentration time
profile
FACTORS EFFECTING THE DESIGN OF OCDDS
Physicochemical properties of drug
Physiological factors
PHYSIOLOGICAL CONSIDERATIONS
Buccal Mucosa
Stomach
Small Intestine
Colon
Mechanism aspects of Oral drug delivery
formulation
1.Dissolution : 1.Matrix
2.Encapsulation
2.Diffusion : 1.Matrix
2.Reservoir
3.Combination of both dissolution &
diffusion.
4.Osmotic pressure controlled system
5.Ion exchange resins
6.Altered density formulations
Solid substances solubilizes in a given solvent.
Mass transfer from solid to liquid.
Rate determining step: Diffusion from solid to liquid.
Matrix Type
Also called as Monolith dissolution
controlled system.
Controlled dissolution by:
1.Altering porosity of tablet.
2.Decreasing its wettebility.
3.Dissolving at slower rate.
Soluble drug
First order drug release.
Drug release determined by
dissolution rate of polymer.
Examples: Dimetane extencaps,
Dimetapp extentabs.
Slowly
dissolving
matrix
Encapsulation
Called as Coating dissolution
controlled system.
Dissolution rate of coat depends
upon stability & thickness of
coating.
Masks
colour,odour,taste,minimising GI
irritation.
One of the microencapsulation
method is used.
Examples: Ornade spansules,
Chlortrimeton Repetabs
Soluble drug
Slowly
dissolving or
erodible
coat
Diffusion
Major process for absorption.
No energy required.
Drug molecules diffuse from a
region of higher concentration to
lower concentration until
equilibrium is attainded.
Directly proportional to the
concentration gradient across the
membrane.
Matrix Diffusion Types
Rigid Matrix Diffusion
Materials used are insoluble plastics such as PVP
& fattyacids.
Swellable Matrix Diffusion
1. Also called as Glassy hydrogels.Popular for
sustaining the release of highly water soluble drugs.
2. Materials used are hydrophilic gums.
Examples :
Natural- Guar gum,Tragacanth.
Semisynthetic : HPMC,CMC,Xanthum gum.
Synthetic -Polyacrilamides.
Examples: Glucotrol XL, Procardia XL
Matrix system
Rate controlling step:
Diffusion of dissolved
drug in matrix.
Reservoir System
Also called as Laminated matrix device.
Hollow system containing an inner core
surrounded in water insoluble membrane.
Polymer can be applied by coating or micro
encapsulation.
Rate controlling mechanism - partitioning into
membrane with subsequent release into
surrounding fluid by diffusion.
Commonly used polymers - HPC, ethyl cellulose
& polyvinyl acetate.
Examples: Nico-400, Nitro-Bid
Reservoir System
Rate controlling
steps :
Polymeric content in
coating, thickness of
coating, hardness of
microcapsule.
Dissolution & Diffusion Controlled
Release system
Drug encased in a partially
soluble membrane.
Pores are created due to
dissolution of parts of
membrane.
It permits entry of aqueous
medium into core & drug
dissolution.
Insoluble
membrane
Entry of
dissolution
fluid
Drug
diffusion
Diffusion of dissolved drug
out of system.
Ex- Ethyl cellulose & PVP
mixture dissolves in water &
create pores of insoluble
ethyl cellulose membrane.
Pore created by
dissolution of soluble
fraction of
membrane
Osmotic Pressure
Controlled System
Osmosis
- Movement of solvent from lower to higher concentration.
- The passage of solvent into a solution through
semipermeable membrane.
Semipermeable Membrane
Molecules are permitted only to one component (Water).
Osmotic pressure
It is the hydrostatic pressure produced by a solution in a space
divided by a semipermeable membrane due to difference in
concentration of solutes.
Osmotic Pressure Controlled
System
Provides zero order release
Drug may be osmotically active, or combined with an
osmotically active salt (e.g., NaCl).
Semipermeable membrane usually made from cellulose
acetate.
More suitable for hydrophilic drug.
Examples: Glucotrol XL, Procardia XL,
Advantages
 Total dose is low.
 Reduced GI side effects.
 Reduced dosing frequency.
 Better patient acceptance and compliance.
 Less fluctuation at plasma drug levels.
 More uniform drug effect
 Improved efficacy/safety ratio.
Disadvantages
Dose dumping.
Reduced potential for accurate dose
adjustment.
Need of additional patient education.
Stability problem.
Some Popular Brand names used for
OCDDS
Spansule capsule ( SK & F )
Sequal capsule (Lederle )
Extentab tablets ( Robins )
Timespan tablet ( Roche )
Dospan tablet
( Merrell Dow )
Chronotab tablet ( Schering )
Plateau capsule ( Marion )
Tempule capsule ( Armour )
Recent Trends:
OROS Technology
(ALZA corporation)
Recent trends:
Geomatrix® (SKY Parma)
References
The theory & practice of industrial pharmacy,
Leon Lachman , Herbert A.Lieberman,
Biopharmaceuitics & pharmacokinetics,
D M.Brahmankar & Sunil B. Jaiswal.
Controlled drug delivery ,S.P.Vyas & Roop .k.khar
Thank you for listening
me………A.F