This document discusses different types of feedback regulated drug delivery systems (FR-DDS). It introduces bio-erosion regulated DDS, bio-responsive DDS, and self-regulated DDS. For bio-erosion regulated DDS, the system consists of a drug dispersed in a bio-erodible matrix. In the presence of urea, the polymer matrix degrades rapidly, releasing the drug. For bio-responsive DDS, the drug reservoir is enclosed in a membrane whose permeability is controlled by the concentration of a biochemical agent like glucose. For self-regulated DDS, the drug is coupled to a sugar and encapsulated in a complex with a lectin protein. Glucose competes for binding sites

1. SUBMITTED TO :
DR. Avinash Hosmani
SUBMITTED BY :
Pratiksha R. Sudrik
(M. PHARM 1st SEM)

2. CONTENT
 Introduction
 concept
 Classification
 Bio-erosion regulated DDS
 Bio responsive DDS
• Discussion of glucose-triggered insulin delivery
 Self-regulated DDS
 REFERENCES

3. INTRODUCTION
• The release of drug from delivery system is
activated by a triggering agent,such as a
biochemical substance ,in the body and also
regulated by its concentration via some feedback
mechanism.
• Rate of drug release is controlled by the
concentration of triggering agent detected by a
sensor in the feedback regulated mechanism.
• Feedback regulated approaches have been used
effectively in insulin release in response to
changing glucose levels for diabetic treatments.

4. Physiological
response
Release of
drug
Rate
controlling
element
Drug
Biochemical
Responsive
sensor

5. Classification
 Bio-erosion-regulated DDS
 Bio-responsive DDS
 Self-regulated DDS

6. 1. Bio-erosion regulated DDS
• The system consist of drug dispersed bio-erodible matrix
fabricated from poly vinyl methyl ether half esters, which is
coated with a layer of immobilised urease ,in a solution with
neutral pH polymer erodes very slowly.
Bio-erodible matrix
u
u
u u u
u
u
u u
u
u
u

7. In the presence of urea, urease at the surface of drug
delivery system metabolizes urea to ammonia.
Causes pH to increase
Rapid degradation of polymer matrix
release of drug molecule .

8. • In this system, the drug reservoir is contained in a
device enclosed by a bio-responsive polymeric
membrane whose drug permeability is controlled by
the concentration of biochemical agent in the tissue
where the system is located.
Biochemical
agent
Ex. Glucose triggered
insulin delivery
system

9.  The insulin reservoir is encapsulated within a hydrogel
membrane having pendant –NR2 groups.
 In alkaline solution, -NR2 groups are neutral and
membrane is un-swollen and impermeable to insulin.
 As a glucose, a triggering agent penetrates into the
membrane to form gluconic acid.
 The NR2 groups are protonated to form NR2H+ and the
hydrogen membrane then become swollen and
permeable to insulin molecules . The amount of insulin
delivered is thus bio- responsive to the concentration of
glucose penetration the insulin delivery system.

10. • This type of FR-DDS depends on a reversible and
competative binding mechanism to activate and to
regulate the release of drug.
• In this system drug reservoir is a drug complex
encapsulated in a impermeable polymeric
membrane.
• The release of drug from the delivery system is
activated by the membrane permeation of a
biochemical agent from the tissue in which the
system is located.

11. Polymer
membrane
Glucose in
G –insulin out
Concanavalin A
(CARBOHYDRATE
BINDING PROTEIN)
Glycosylated
(G) insulin

12.  Reversible binding of sugar molecules by a lectin in the
design of self regulating DDS.
 It first involved preparation of biologically active insulin
derivative in which insulin coupled with sugar(maltose)
and this into an insulin-sugar-lectin complex.
 The complex is then encapsulated within a semi-
permeable . As blood glucose diffuses in the device and
competatively binds at the sugar binding sites in lectin
molecules, this activated the release of bound insulin-
sugar derivatives.
 The release insulin-sugar derivative then diffuses out and
the amount of insulin sugar derivative depends on the
glucose concentration thus a self regulating drug delivery
is achieved.

13. • Y. W. Chein; “Novel drug delivery system :Fundamentals, Developmental
concept and biomedical assesments”. Dekker,New york(1982). Page 1-132
• Robinson, “FUNDAMENTALS OF CONTROLLED DRUG DELIVERY SYSTEM”, PAGE
NO 482-508
REFERENCES