Rate controlled drug delivery system achieved by using some polymers and predetermined release of drug from reservoir. CRDDS Avoids problems regarding conventional drug delivery

1. RATE CONTROLLED DRUG DELIVERY
SYSTEM
 Presented by-
 Miss Khade S.B
 M.Pharm-1 [pharmaceutics department]
 RCP , Kasegaon
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2. Content-
Introduction
Need of rate controlled DDS
Advantages
Disadvantages
Classification
Mechanism CDDS
Activation modulated drug delivery system
 Effect of system parameters on controlled DDS
Applications of Rate controlled DDS
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3. Introduction
“The term controlled release may be defined as a
technique or approach by which the drug is
delivered at predetermined rate , for locally or
systemically for a specified period of time”
 controlled delivery of drug or protein and
bioactive agent can be achieved by incorporating
them either in dissolved or dispersed form in
polymer.
Follow “ZERO ORDER DRUG RELEASE”
Rapidly attained required plasma concentration
and maintained for the entire period of treatment.
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4.  Need of rate controlled DDS
 Less fluctuation in drug blood level
 Frequency reduction in dosing
 Improving patient convenience and compliances
 Increased safety margin of the high potency drug
 Reduction in total health care cost
 Suitable DDS for drug having “ short biological half
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5.  Disadvantages
 Dose dumping
 Decreased systemic availability in comparision to
immediate release conventional dosage form
Poor in vivo- in vitro correlation
Possibility of dose dumping
Difficult to optimize the accurate dose and dosing
interval
Patient variability affects release rate i.e GI emptying
rate, fasting or non fasting condition
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6. Controlled Release system[Mechanism]
Controlled
release system
Dissolution
controlled
Diffusion
controlled
Chemically
controlled
Ion –
exchange
resin Hydrogel
Water
penetration
controlled
Diffusion
and
dissolution
Matrix
Encapsulation
Matrix
Reservoir
Reservoir
and
monolithic
Osmotic
pressure
controlled
system
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7.  Classification
Based on their technical sophistication
1. Rate preprogrammed drug delivery system
2. Activation modulated drug delivery system
3. Feedback regulated drug delivery system
4. Site targeting drug delivery system
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8.  RATE PREPROGRAMMED DDS
 Polymer membrane permeation controlled DDS
Release of drug controlled by-
 partition coefficient of drug
 Diffusivity of drug molecule
 Thickness of rate controlling membrane
e.g. progestasert
 Polymer matrix diffusion controlled DDS
Release of drug controlled by-
 Loading dose
 Polymer solubility
 Drug diffusivity in polymer matrix
e.g. Nitro- Dur
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9.  Micro reservoir partition CDDS
Release controlled by-
 Partition coefficient
 Diffusivity of drug
 Solubility of drug
e.g. Syncro-mate-c ,Nitrodisc
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10.  Activation modulated DDS
“The release of drug molecule from the DDS is
activated by some physical, chemical or biochemical
process or energy supplied externally”
Based on nature of energy used –
1.By physical means
 Osmotic activated DDS e.g. Alzet osmotic
pump
 Hydrodynamic pressure activated DDS
 Mechanically activated DDS
 Magnetically activated DDS
 Sonophoresis activated DDS
 Iontophoresis activated DDS
 Hydration activated DDS 10/09/2019 10Rate controlled DDS

11. 2.Chemical means
 pH activated DDS e.g. Salts of citric acid ,
cellulose derivatives
 Ion activated DDS
 Hydrolysis activated DDS
3.Biochemical means
 Enzyme activated DDS
 Biochemical activated DDS
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12.  Feedback activated DDS
“Rate of drug release is controlled by concentration triggering
agent”
Classified as-
 Bioerosion regulated DDS e.g. Hydrocortisone
 Bioresponsive DDS e.g. Glucose triggered insulin
 Self regulating DDS e.g. Glycosylated insulin
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13.  Effect of system parameters-
 Physiological properties
 Polymer solubility
 solution solubility
 Partition coefficient
 Polymer diffusivity
 Solution diffusivity
 Thickness of polymer diffusional path
 Thickness of hydrodynamic diffusional layer
 Molecular size [400 Dalton] ,Drug pKa
 Drug stability , Protein binding
 Biological factors-Absorption ,Half life[2-3hrs]
Dose size, Therapeutic and Absorption window,
patient physiology
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14.  Applications of CDDS
 Adsorbent of toxin
 As Antacids
 As Bile Acid binding agent
 In treatment of Liver diseases
 In Renal insufficiency
 In Ophthalmology for glaucoma
Therapeutic application
1.Cholestyramine –Reduction of elevated serum
cholesterol level in patients with hypercholesterolemia
2. Sod. Polystrene –Sulphonic cation exchange resin
used in treatment of renal failure
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Conclusion
A suitably deliberate controlled release drug delivery
system can be significant progress towards solving problems
regarding the targeting of the drug a particular organ or
tissue and controlling the rate of drug delivery to the target
site . Controlled release stuff provide an advantage over
conventional quality from by optimizing bio- pharmaceutics
pharmacokinetics and pharmacodynamics properties of
medicinal product
With improved understanding of controlled release
mechanism and improved development of technologies, it
may possible to design an appropriate method for efficient
drug delivery system at particular site

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