1. A SEMINAR
ON
ORAL CONTROLLED DRUG
DELIVERY SYSTEM
PRESENTED BY
SONAM M. GANDHI
2. INTRODUCTION
Oral controlled drug delivery system is
a delivery system that provides the
continuous oral delivery of drugs at
predictable and reproducible kinetics for a
determined delivery throughout the course
of GI transit.
3. Advantage
• Reduce dosage frequency
• Reduce fluctuation in circulating drug level
• Increase patient compliance
• Avoidance of night time dosing
• More uniform effect
• Reduction in GI irritation and dose related
side effects
4. Disadvantage
• Highly expansive
• Often poor in vivo-in vitro correlation
• Dose dumping
• poor systemic availability
5. DESIGN AND FABRICATION OF
ORAL STATEM
Dissolution controlled release systems
Diffusion controlled release system
Dissolution & diffusion controlled
release system
Ion exchange resin drug complex
pH dependant formulation
Osmotic pressure controlled systems
Hydrodynamic pressure controlled
systems
6. DISSOLUTION CONTROLLED
RELEASE SYSTEM
• Sustain release oral products employing
dissolution as the rate limiting step are
the principle involves in this system.
• To achieve this type of approach , the
drug particles can be coated with
material of varying thickness or by
dispersing them in a polymeric matrix.
7. The common forms of dissolution controls formulation are
shown below
MEMBRANE
DRUGS
(a) Dissolution controls of drugs release depends on
thickness & dissolution rate of the membrane coat
(b) Dissolution control of drugs release depends on polymer
core erosion
8. • Dissolution controlled drug release system can be
divided in to two categories:
(1) Encapsulation Dissolution control
(2) Matrix Dissolution control
(1) Encapsulation Dissolution control:
This method involves the coating of particles or
granules of drug with slow dissolving materials
9. GRANULES COATED PRODUCT
• There are several ways to prepare a drug coated
product.
• A common method is to coat the seeds with the
drug followed by a coat of slow dissolving
materials such as carbohydrate sugar and
cellulose ,polyethylene glycol, polymeric
material, and wax.
11. (2) MATRIX DISSOLUTION CONTROL:
• It is also called as monoliths.
• The drug is dispersed in media such as bees wax,
carnauba wax, caster oil etc which control drug
dissolution by controlling the penetration of
dissolution fluid in to matrix.
• This can be controlled by altering the porosity of the
tablet matrix, the presence of hydrophobic
additives, and the wettability of the tablet and
particle surface.
12. DIFFUSION CONTROLLED RELEASE
SYSTEM
• There are two type of the diffusion controlled
release system :
(1) Reservoir devices
(2) Matrix devices
13. • (1) Reservoir devices
WATER INSOLUBLE
POLYMERIC MEMBRANE
DRUG
• The drug release mechanism across the
membrane involves its partitioning into the
membrane and release into the surrounding fluid by
diffusion.
14. • The flux of drug, J , across a membrane in the
direction of decreasing concentration is given by
Fick's first law;
J = - D dc / dx
D = Diffusion coefficient in area/ time
dc/dx = change of concentration with distance
• In term of the amount of drug release , the release
rate is given by
dM / dt = ADK ΔC / l
15. A = area
D = diffusion coefficient
K = the partition coefficient of the drug between
the membrane and drug core
l = diffusion path length
ΔC = concentration difference across the
membrane
16. • (2) Matrix devices:
Diffusion controls of drugs release by solid drugs dispersed in
an insoluble matrix
• In this system, a solid drug is dispersed in an insoluble
matrix.
• The rate of drug release is dependent on THE RATE
OF DRUG DIFFUSION but not THE RATE OF SOLID
Dissolution.
17. • The drug release from this system is given by
following equation
Q = [ Dε / T ( 2A - εCs ) Cs t ]1/2
Q = weight in grams of drug released per unit surface
area
D = diffusion coefficient of drug in the release medium
ε = porosity of matrix
T = tortuosity of the matrix
Cs = solubility of drug in the release medium
A = concentration of drug in the tablet
18. DIFFUSION AND DISSOLUTION
CONTROLLED SYSTEM
• The main feature of this system is that the drug
core is enclosed with a partially soluble
membrane.
drug
Partially Soluble membrane
Pores produced by soluble portion of
Polymer membrane
19. • The release profile of the drug from this type of
the product can be described by following
equation :
Release rate = AD ( C1 – C2 ) / l
A = surface area
D = diffusion coefficient of the drug through
pores
l = Diffusion pathways
C1 = concentration of drug in cores
C2 = concentration of drug in dissolution
medium
20. • The fraction of soluble polymer in the coat will be the
dominant factor controlling drug release.
• Such a system has been demonstrated to provide a
zero order release of Kcl from a tablet and doing the
minimize gastrointestinal irritation effect of this
compound.
21. Ion exchange resin
• This method involves the drug release
characteristics depends on the ionic
environment of the resin containing drug and
should be less effective to the environmental
condition such as enzyme content end pH.
•
Resin[N(CH3)]+X¯ + Z -
(Drug-charged resin) Resin [N(CH3)]+Z + X -
22. • The release rate can be controlled by coating the
drug resin complex using the one of the
microencapsulating process.
Polymer coating
Drug containing resin granules
23. • Improvement of this ion exchange type drug delivery
system is occurs by the development of the
pennkinetic system.
• In these system, the drug containing resin granules
treated with the polymer such as PEG- 400 and further
coated with the water soluble polymer such as ethyl
cellulose act as a rate limiting barrier to control the
drug release.
Ethyl cellulose coating
Drug containing resin
granules
Poly ethylene glycol coating
24. pH – INDEPENDENT CONTROLLED
RELEASE SYSTEM
• This system involves the granules are designed
for the oral controlled release of acidic and basic
drugs at the rate that is independent of the ph in
the GI tract.
• They are prepared by mixing a basic or acidic
drugs with one or more buffering agents
,granulating with excipients and finally coating
with a GI fluid permeable film forming polymer.
25. • When the GI fluid permeates through the membrane ,
the buffering agents adjust the suitable constant ph,
there by constant rate of the drugs release occurs.
26. OSMOTICALLY CONTROLLED RELEASE
SYSTEM
• In this type of drug delivery system, the osmotic pressure
is the driving force that generates constant drug release.
Osmotic delivery orifice
Semi permeable membrane
Osmotic core reservoir containing drug
27. • To regulate the flow of GI fluid for penetrstion
through the semi permeable membrane, a layer of
bioerodible polymer can be applied to the external
surface of the semi permeable membrane
• Several other modification of osmotic pressure
controlled drug delivery have been develop.
• One system consists of two compartments separated
by the movable partition
Semi permeable membrane
Drug reservoir
Movable partition
Osmotically active compartment
28. • Another modified system is one in which delivery
orifice is absents .In these system, the GI fluid is
penetrate, hydraulic pressure is built up inside until
the wall ruptures and the contents are release to
the environments.
• Osmotic controlled release system requires
osmotic pressure to be effective and is independent
of its environments.
29. HYDRODYNAMICAL LY BALANCE
SYSTEM
• This system is design to prolong GI residence
time of drug in area of the GIT to minimized drug
reaching its absorption site in the solution state.
• This type of the tablet or capsules having the
less density compared to the GI fluid density.
• This type of tablet is prepared by granulating a
mixture of drug, excipients, and hydrocolloids
such as hydroxyethylcellulose, hydroxypropyle
cellulose, and hydroxypropylmethylcellulose.
31. Effervescent Floating Dosage Form
• These are matrix type of system prepared with
swellable polymer such as methylcellulose,
chitosan, and various effervescent compounds
like sodium bicarbonate, tartaric acid, and citric
acid.
• These type of tablet comes in contact with the
acidic gastric contents, Co2 is liberated and gets
entrapped in swollen hydrocolloids, providing
buoyancy to the dosage form.
32. Non effervescent Floating dosage Form
• This system is prepared from gel forming or swellable
cellulose type of hydrocolloids, polysaccharides,
and matrix forming polymer like acrylates.
• After the oral administration, this dosage forms sweiis
in contact with gastric fluid and attain a bulk density of
G.I.
• The air entrapped within the swollen matrix imparts
buoyancy to dosage form.
• The formed swollen gel – like structure acts as a
reservoir and allows sustained release of drug through
the gelatinous mass.
