1. CONTROLLED RELEASE ORAL DRUG DELIVERY SYSYTEMS
DEPT.OF .PHARMACEUTICS

2. 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

3. FACTORS EFFECTING THE DESIGN OF OCDDS
Physicochemical properties of drug
Physiological factors
PHYSIOLOGICAL CONSIDERATIONS
Buccal Mucosa
Stomach
Small Intestine
Colon

4. 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

5. 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.
First order drug release.
Drug release determined by dissolution rate of polymer.
Examples: Dimetane extencaps, Dimetapp extentabs.
Soluble drug
Slowly dissolving matrix

6. 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

7. 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.

8. 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

9. Matrix system Rate controlling step: Diffusion of dissolved
drug in matrix.

10. 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

11. Reservoir System
Rate controlling steps :
Polymeric content in coating, thickness of coating, hardness of microcapsule.

12. 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.
Diffusion of dissolved drug out of system.
Ex- Ethyl cellulose & PVP mixture dissolves in water & create pores of insoluble ethyl cellulose membrane.
Insoluble membrane
Entry of dissolution fluid
Drug diffusion
Pore created by dissolution of soluble fraction of membrane

13. 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.

14. 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,

16. 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.

17. Disadvantages
Dose dumping.
Reduced potential for accurate dose adjustment.
Need of additional patient education.
Stability problem.

18. 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 )

19. Recent trends: Geomatrix® (SKY Parma)
Recent Trends: OROS Technology (ALZA corporation)
Recent trends: Geomatrix® (SKY Parma)

20. 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

21. Thank you for listening me………A.F