Feedback regulated drug delivery system is comes under activated modulated drug delivery system

1. SRI ADICHUNCHANAGIRI COLLEGE OF PHARMACY B G NAGAR
SEMINAR 0N:
FEEDBACK REGULATED DRUG
DELIVERY SYSTEM
PRASHANTA TAVARI
M.PHARM 1ST YEAR
DEPT OF PHARMACEUTICS
SACP

2. FEEDBACK-REGULATED DRUG DELIVERY
SYSTEM
 In this group of CrDDSs, the release of drug molecules
is activated by a triggering agent, such as a biochemical
substance, in the body via some feedback mechanisms.
 The rate of drug release is regulated by the concentration
of a triggering agent detected by a sensor
built into the CrDDS.

3. CLASSIFICATION
1. Bioerosion–regulated drug delivery system
2. Bioresponsive drug delivery system
3. Self–regulating drug delivery system

4. 1.Bioerosion–regulated drug delivery system
.Heller and Trescony developed bioerosion-regulated drug
delivery system.
.This CrDDS consists of a drug-dispersed bioerodible matrix
fabricated from poly(vinyl methyl ether) half-ester, which
was coated with a layer of immobilized urease.
.In a solution with near neutral pH, the polymer erodes
very slowly.
. In the presence of urea, urease at the surface of the drug
delivery system metabolizes urea to form ammonia.

5.  This causes the pH to increase and activates a rapid degradation
of polymer matrix as well as the release of drug molecules.
Fig:- Cross-sectional view of a bioerosion-regulated
hydrocortisone delivery system, a feedback-regulated drug
delivery system, showing the drug-dispersed monolithic
bioerodible polymer matrix with surface-immobilized
ureases

6. 2.Bioresponsive drug delivery system
 The feedback-regulated drug delivery concept has also been
applied to the development of a bioresponsive CrDDS by
Horbett.
 In this CrDDS, the drug reservoir is contained in a device
enclosed by a bioresponsive polymeric membrane whose
permeability to drug molecules is controlled by the
concentration of a biochemical agent in the tissue where the
CrDDS is located.

7.  A typical example of this bioresponsive CrDDS is the
development of a glucose-triggered insulin delivery system, in
which the insulin reservoir is encapsulated within a hydrogel
membrane containing pendant NR2 groups.
 In an alkaline solution, the NR2 groups exist at neutral state
and the membrane is unswollen and thus impermeable to
insulin.
 As glucose penetrates into the membrane, it is oxidized
enzymatically by the glucose oxidase entrapped in the
membrane to form gluconic acid.

8.  This process triggers the protonation of NR2 groups to form
NR2H+, and the hydrogel membrane becomes swollen and is
thus permeable to insulin molecules.
 The amount of insulin delivered is bioresponsive to the
concentration of glucose penetrating into the CrDDS.

9. Fig:- Cross-sectional view of a bioresponsive insulin
delivery system, a feedback-regulated drug delivery system,
showing the glucose oxidase-entrapped hydrogel membrane
constructed from amine-containing hydrophilic polymer.
The mechanism of insulin release, in response to the influx
of glucose, is also illustrated.

10. 3.Self–regulating drug delivery system
 This type of feedback-regulated CrDDS depends on a reversible
and competitive binding mechanism to activate and to regulate
the release of drug.
 A drug complex is encapsulated within a semipermeable
polymeric membrane.
 The release of drug from the CrDDS is activated by the
membrane permeation of a biochemical agent from the tissue
where the CrDDS is located.
 Kim et al, first applied the mechanism of reversible binding of
sugar molecules with lectin.

11.  For this CrDDS,
 a biologically-active insulin derivative, in which insulin is
coupled with a sugar (e.g., maltose), was first prepared and then
conjugated with lectin to form an insulin–sugar–lectin
complex.
 This complex is then encapsulated within a semipermeable
membrane.
 As blood glucose diffuses into the CrDDS, it binds,
competitively, with the binding sites in the lectin molecules and
activates the release of the insulin–sugar derivatives from the
binding sites.
 The amount of insulin-sugar derivatives released depends on
the concentration of glucose. Thus, a self-regulating drug
delivery is achieved.

12.  Further development of the self-regulating insulin delivery
system has utilized the complex of glycosylated insulin–
concanavalin A, which is encapsulated inside a polymer
membrane.
 As glucose penetrates into the system, it activates the release of
glycosylated insulin from the complex for a controlled release
from the system.
 The amount of insulin released is thus self-regulated by the
concentration of glucose that has penetrated into the insulin
delivery system.

13. Fig:- Various components of a self-regulating
insulin delivery system, a feedback-regulated
drug delivery system.

14. REFERENCE
1. Novel Drug Delivery System By Yie W. Chien
second edition
2. Controlled and Novel Drug Delivery By
N.K.Jain

15. Thank you