CRDDS are playing an important role in the advancement of optimum and effective drug delivery compared to conventional delivery systems .

1. Controlled Release Drug Delivery
Systems(CRDDS)
By Miyanda Petty. M
M.Pharmaceutics
CT Institute of Pharmacetical Sciences

2. Contents
• Definition
• Rationale
• Advantages
• Factors influencing design of CRDDS
• Characteristics making drug unsuitable for
CRDDS formulation
• Classification

3. Definition
• Refers to the use of a delivery device with the
objective of releasing drug at a predetermined
rate or at specific times or with specific
release profiles
• They provide a release profile independent of
the external environment and predominantly
controlled by the design of the system

4. • Controlled release systems are multiple dose
systems designed to achieve a steady state of
concentration.

5. Rationale of controlled drug delivery
• The basic idea behind controlled drug delivery concept is to
alter the pharmacokinetics and pharmacodynamics of
bioactives either by modifying the molecular structure ,and
• or physiological parameters by an alternative route of
administration or by using novel drug delivery systems .
• The primary objective of CRRDS is to ensure safety and
enhance efficacy of drug with improved patience compliance

6. Advantages of CRDDS
• Controlled delivery of active agent at predetermined
rate
• Maintenance of optimal and effective drug level for
prolonged periods
• Reduction of untoward effects like git irritation
• Increased patient compliance

7. • Reduction in dosing frequency
• Drug delivery in the vicinity of site of action
• More efficient utilization of active ingredient
• Avoidance of night time dosing

8. Factors Influencing Design of Controlled Release Dosage Forms
Variables to be considered for design of controlled release
products:
• Drug related (physicochemial properties of he drug)
Aqueous solubility ,partition coefficient ,stability ,charge
,molecular size and protein binding .
• Biological factors
Absorption,distribution,elimination,duration of action,magin of
safety,side effects

9. • Physiological factors
Gastrointestinal blood flow, variability in GI
emptying and motility. prolonged drug
absorption
• Pharmacokinetic factors
Dose dumping, first pass metabolism ,variability
of urinary PH effect on drug elimination

10. • Acute or chronic therapy-expected length of therapy to
achieve cure or control of disease
• Target sites -untoward effects can be minimized by
localization of drug to desired area by use of novel carriers
• patient factors
Patient condition whether ambulatory or bed riddden, obese
or gaunt, age (young/old )

11. • Disease state
Hepatic failure-oral drug delivery sould be
avoided.Renal failure ,heart failure(evaluate
bllod flow) etc

12. Characteristics of Drug Molecule Rendering it
Unsuitable for Controlled Release Dosing
• Too short /long elimination half life
• Narrow therapeutic index
• Poor absorption
• Large doses
• Low aqueous solubility
• Extensive first pass metabolism

13. Classification of Controlled Release
Systems
Type of system Rate control mechanism
Diffusion controlled
reservoir systems
Monolithic systems
Diffusion through membrane (both)
Water penetration controlled
Osmotic systems
Swelling systems
Osmotic transport of water through semi
permeable membrane
Water penetration into glassy polymer
Chemically controlled
Monolithic systems
Pendent systems
Ion exchange resins
Either by surface erosion or combination
with bulk erosion
Combination of hydrolysis of pendent
group and diffusion from bulk polymer
Exchange of acidic or basic drugs with the
ions present on resins

14. Type of system Rate control mechanism
Regulated system
Magnetic ,ultrasound
Chemical
External application of magnetic field of
ultrasound to device.
Use of competitive desorption or enzyme
substrate reactions. Rate control is built
into device.

15. Advantages and Disadvantages of Matrix and Reservoir systems
Matrix system Reservoir system
Very easy to fabricate in a wide range of
size and shapes.
Achievement of zero order release is easy
Suitable for both non-gradable and
degradable systems.
Very easy to fabricate in wide range of
sizes and shapes
No danger of dose dumping in case of
rupture .
Drug inactivation by contact with the
polymeric matrix can be avoided
Achievement of ‘zero order ‘ release is
difficult not all drugs can be blended with
a given polymeric matrix
Rupture can result in dangerous dose
dumping
Water soluble drugs have a tendency to
’burst’ from the system
Degradable reservoir systems may be
difficult to design