it describes the various types of rate controlled drug delivery devices and their examples and functioning.

1. VariousVarious
raTE-CoNTroLLEDraTE-CoNTroLLED
DruG DELiVErYDruG DELiVErY
sYsTEMssYsTEMs
PrEsENTED BY :-
ishiTa BajPai
Masters in Pharmaceutics

2. Contents :
 Introduction : definition of controlled drug delivery
systems (C.D.D.S)
 Advantantages and Disadvantages
 Types of rate controlled drug delivery systems
 Examples of each device and their functioning
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3. INTRODUCTION
i. Sustained release,
ii. sustained action,
iii. controlled release,
iv. extended action,
v. timed release dosage forms
Are the terms used to identify drug delivery systems that are
designed to achieve a prolonged therapeutic effect by
continuously releasing medication over an extended period of
time after the administration of single dose.
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4. June 5, 2016 4
Controlled release :
Usually represents those systems from which therapeutic agents may be
AUTOMATICALLY DELIVERED at PREDEFINED RATES over a long
period of time.
It also implies a predictability & reproducibility in the drug release kinetics,
which means that the release of drug ingredient from a controlled delivery
system proceeds at a rate profile that is not only predictable kinetically, but
also reproducible from one unit to another.
Sustained Release :
 Describes a pharmaceutical dosage form formulated to RETARD the release
of a therapeutic agent such that its appearance in the systemic circulation is
delayed &/or prolonged & its plasma profile is sustained in duration.

5. ADVANTAGES :
1. Less drug blood levels fluctuation.
2. dosing frequency reduces.
3. Improved patient convenience & compliance.
4. Avoidance of night time dosing.
5. More uniform effect.
6. Reduction in GI irritation and dose related
side effects
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6. DisadvantagesDisadvantages
1. Decreased systemic availability in comparison to
immediate release conventional dosage forms.
2. Poor in vivo – in vitro correlation.
3. Possibility of dose dumping.
4. Retrieval of drug is difficult.
5. Higher cost of formulation.
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7. CLASSIFICATION
Based on their technical sophistication :
Rate preprogrammed drug delivery system
Activation-modulated drug delivery system
Feedback-regulated drug delivery system
Site targeting drug delivery system
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8. RATE PRE-PROGRAMMEDRATE PRE-PROGRAMMED
DRUG DELIVERY SYSTEMDRUG DELIVERY SYSTEM
 In this group , the release of drug molecule from the
system has been pre-programmed at specific rate
profile.
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9. RATE PRE-PROGRAMMED
CLASSIFICATION
1. Polymer membrane permeation-controlled drug
delivery system
2. Polymer matrix diffusion-controlled drug delivery
system
3. Micro-reservoir partition-controlled drug delivery
system
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10. 1.Polymer Membrane Permeation-1.Polymer Membrane Permeation-
controlled Drug Delivery Systemcontrolled Drug Delivery System
Herein, drug is totally or partially encapsulated within drug
reservoir.
Its drug release surface is covered by a rate-controlling
polymeric membrane having a specific permeability.
Drug reservoir may exist in solid, suspension or solution
form.
Polymeric membrane may be nonporous or microporous i.e
semipermeable membrane.
Encapsulation of the drug formulation inside the
reservoir compartment is accomplished by
injection,spray-coating,capsulation
or micro-encapsulation.
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June 5, 2016 1010
Polymer membrane
Drug
reservoir
Drug release

11. Drug release is controlled by :
 Partition coefficient of the drug molecule.
 Diffusivity of the drug molecule.
 The thickness of the rate controlling
membrane.
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12. Progestasert intra-uterine device
Example #1
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13. Progestasert Intra UterineProgestasert Intra Uterine
DeviceDevice
arrangement :
drug reservoir (D.R) = progesterone -barium
sulphate suspension in silicone medical fluid.
D.R encapsulated in vertical limb of a T-
shaped device walled by a non-porous
membrane of ethylene-vinyl acetate co-
polymer.
Designed to deliver natural progesterone
continuously in uterine cavity at a daily dosage
rate of at least 65 μg/day to achieve
contraception for 1 year.
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14. June 5, 2016 14
Example #2
Ocusert

15. In the Ocusert system the drug reservoir is a thin
disk of Pilocarpine alginate complex
sandwitched between two transparent sheets
of etylene vinyl acetate copolymer membrane.
Microporous membrane permit the tear fluid to
penetrate into the drug reservoir compartment
to disssolve pilocarpine from the complex
Pilocarpine molecules are then released at a
constant rate of either 20or 40 µg/hr for the
management of glaucoma for upto 7 days
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16. D
Example
Transderm- Nitro
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Adhesive layer

17. Transderm Nitro: Working
Drug resevoir , nitroglycerine-lactose triturate
dispersion in the silicon medical fluid, encapsulated
in thin ellipsoidal patch.
It is constructed from a drug impermeable metallic
plastic laminate as the backing membrane and a
constant surface of rate controlling microsporous
membrane of etylene- vinyl acetate copolymer as the
drug releasing surface
Deliver nitroglycerine at dosage rate of 0.50
mg/cm²/day for transdermal absorption to provide
daily relief from Angina attacks
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18. 2.Polymer Matrix Diffusion-controlled Drug2.Polymer Matrix Diffusion-controlled Drug
Delivery SystemDelivery System
Drug reservoir is prepared by homogeneously dispersing
drug particle in rate controlling polymer matrix from either
a lipophilic or a hydrophilic polymer.
The drug dispersion in the polymer matrix is accomplished
by either,
1. blending therapeutic dose of drug with polymer or highly
viscous base polymer, followed by cross linking of polymer
chains. OR
2. mixing drug solid with rubbery polymer at elevated temp.
18
18
Drug dispersed in polymer matrix
Polymer membrane
drug release
Drug depletion
zone
drug release

19. The rate of the drug release from this
system,
Q = (2ACRDp)1/2
t½
Where,
Q/t1/2 - rate of release of drug
A – initial drug loading dose in the
polymer matrix
CR – drug solubility in polymer
Dp – drug diffusivity in polymer matrixJune 5, 2016 19

20. Release of drug molecule is controlled by
Loading dose
Polymer solubility of drug
Drug diffusivity in polymer matrix.
Example . Nitro-Dur :
Nitro-Dur is a transdermal system contains
nitroglycerin in acrylic-based polymer adhesives
with a resinous cross-linking agent to provide a
continuous source of active ingredient.
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21. Nitro dur
21
It is designed for application on to intact skin for 24
hrs to provide a continuous transdermal infusion of
nitroglycerin at dosage rate of 0.5 mg/cm2
/day for
the treatment of angina pectoris.

22. 3.Microreservior Partition-controlled3.Microreservior Partition-controlled
Drug Delivery SystemDrug Delivery System
Here, drug reservoir is fabricated by micro
dispersion of an aqueous Suspension of drug in
biocompatible polymer such as silicon elastomers to
form homogeneous dispersion .
Depending upon the physicochemical properties of
drugs & desired rate of drug release, the device can
be further coated with a layer of biocompatible
polymer to modify the mechanism & the rate of drug
release.
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22
Microdispersion of drug in biocompatable polymer
Polymer membrane
drug release.

23. Release of drug molecules from this type of
system can follow either a dissolution or a matrix
diffusion controlled process
Release of drug molecule is controlled by,
Partition coefficient
Diffusivity of drug
Solubility of drug
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24. Example #1: Syncro Mate - C
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25. June 5, 2016 25
 It is fabricated by dispersing the drug
reservoir, which is a suspension of
Norgestomet in an aqueous solution of PEG
400, in a viscous mixture of silicone elastomer,
 After catalyst addition, suspension will be
delivered into silicone medical grade tubing,
which serves as mold as well as the coating
membrane & then polymerized in situ.
 The polymerized drug polymer composition is
then cut into a cylindrical drug delivery device
with the open ends.
 It is designed to be inserted into the
subcutaneous tissue of the livestock’s ear flap
& to release Norgestomet for up to 20 days for
control of estrus & ovulation as well as for up
to 160 days for growth promotion.

26. Transdermal Nitro disc
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27. June 5, 2016 27
Drug reservoir is formed by a suspension of
nitroglycerine and lactose triturate in aqueous solution
of 40% polyethylene glycol 400 and dispersing it with
isopropyl palmitate as dispersing agent , in a mixture of
viscous silicone elastomer.
Drug polymer dispersion is then molded to form a solid
medicated disk in situ on a drug –impermeable metallic
plastic laminate, with surrounding adhesive rim, by
injections molding under instantaneous heating.
Transdermal administration of nitroglycerine at a daily
dosage of 0.5 mg/cm² for once a day medication of
angina pectoris.

28. IshIta BajpaI
Thank you friends and viewersThank you friends and viewers
June 5, 2016 28