Drug delivery system

1. SUSTAINED & CONTROLLED DDS
Submittedby,
SRIPRYA S
M.PHARM 1st year
DRUG DELIVERY SYSTEM
DEPARTMENT OF PHARMACEUTCS

2. CONTENTS
 Definition of SR and CRDDS
 Comparsion of drug release profile
 Advantages and disadvantages of SDR and CRDDS
 Drug selection criteria for SR and CRDDS
 Classification of oral SR and CRDDS
 Evaluation of SR and CRDDS
 Application of SR and CRDDS
 Conclusion
 References

3.  SUSTAINED DRUG DELIVERY SYSTEM
Sustained release are drug delivery system that achieve
slow release of drug over an extended period of time after
administration of single dose.
 CONTROLLED DRUG DELIVERY SYSTEM
Controlled Drug delivery system is one which delivers
the drug at predetermined rate, for locally or systemically for
specified period of time.
These drug maintain constant level of drug in blood and
tissue for extended period of time.

4. COMPARISON OF DRUG RELEASE PROFILE

5. ADVANTAGES
 Improve absorption, utilization and there by enhancing
bioavailability.
 Decreased local and systemic side effects reduced gastrointestinal
irritation.
 Reduction in dosing frequency
 Better patient acceptance and compliance
 Reduced fluctuations in circulating drug levels
 Bioavailability of certain drugs can be increased.

6. DISADVANTAGES
 Dose dumping.
 Dose adjustment is difficult.
 Patient education is required for successful therapy.
 Patient need to substantial additional information as to the proper
used sustained release product.
 Poor IVIVC.
 Higher cost of single unit as compared to cost of single
conventional unit.
 Stability problems.

7. DRUG SELECTION CRITERIA FOR ORAL
SUSTAINED AND CONTROLLED DRUG DELIVERY
SYSTEM.
 Physicochemical properties of drug
 Pharmacokinetic properties of drug
 Pharmacodynamic properties of drug

8. PHYSICOCHEMICAL PROPERTIES OF DRUG
i. Molecular weight of the drug.
ii. Aqueous solubility of drug.
iii. Apparent partition or coefficient of drug.
iv. Drug Pka and ionization at physiological pH
v. Drug stability
vi. Mechanism and site of action
vii. Biopharmaceutical aspect of route of administration
viii.Oral route
ix. Intramuscular or subcutaneous route
x. Transdermal route

9. 2) PHARMACOKINETIC PROPERTIES OF DRUG
i. Absorption rate
ii. Elimination half life
iii. Rate and extent of metabolism
iv. Dosage form index
v. Plasma protein binding
3) PHARMACODYNAMIC PROPERTIES OF DRUG
i. Therapeutic index or range
ii. Plasma concentration responses relationship

10. CLASSIFICATION OF ORAL SR and CRDDS
 Continuous release system
 Delayed transit and continuous release system
 Delayed release system

11. Continuous release system
 These systems release the drug continuously for prolonged period of
time along the entire length of GIT with normal transit time.
Different systems under this class are-
a. Dissolution controlled release system
b. Diffusion controlled release system
c. Dissolution and diffusion controlled release system
d. Ion exchange drug resin complexes
e. Slow dissolving salts and complexes
f. pH- dependent formulation
g. Osmotic pressure controlled release system
h. Hydrodynamic pressure controlled release system

13. a. DISSOLUTION CONTROLLED RELEASE
SYSTEM
 These system are most commonly employed in the production of enteric coated
dosage forms. Drug present in the system having high aqueous solubility and
dissolution rate.
 MATRIX SYSTEM
Matrix system are also called as monoliths since the drug is homogenously
dispersed throughout a rate-controlling medium.
example: Bees wax, carnuba wax, hydrogenated castor oil
Soluble drug
Slowly
dissolving
matrix

14.  RESERVOIR SYSTEM
The drug particle are coated or encapsulated by one of the several
microencapsulation Techniques with slowly dissolving materials like cellulose,
PEG, polymethacrylates, waxes, etc.
Soluble
drug Slowly
dissolving
or erodible
coat

15. b. DIFFUSION CONTROLLED RELEASE SYSTEM
 Movement of drug molecules from a region of a higher concentration to one of
lower concentration.
MATRIX SYSTEM
The drug is dispersed in an insoluble matrix of rigid nonswellable
hydrophobic materials or swellable hydrophilic substances.
RESERVOIR SYSTEM
These system are hollow containing an inner core of drug surrounded in a
water insoluble polymer membrane.

16. c. Dissolution and diffusion controlled
release system
d. Ion exchange resin- drug complex
 Is based on preparation of totally insoluble ionic material.
 Resins are insoluble in acidic and alkaline media they contain ionizable groups
which can be exchanged for drug molecules.

17. e. Slowly dissolving salts and complexes
Salt or complexes of drug which are slowly soluble in the GI fluid can be used for
controlled release of the drug.
e.g. Penicillin G has been complexed with N,N- dibenzyl ethylene diamine , ethylene diamine
to give benzathine penicillin G.
f. Osmotic pressure controlled release system
The flow of the liquid into the release unit driven by a difference in osmotic pressure
between the inside and the outside of the release unit is used as the release- controlling process.

18. G. Hydrodynamic pressure controlled release
system
It control molecular diffusion of drug molecules in or across barrier medium within
or surrounding the deliver system.
H. pH-dependent formulations
Such system are designed to eliminate the influence of GI pH on dissolution and
absorption of drugs formulating them with sufficient amount of buffering agents like
salts of phosphoric, citric , tartaric acids. That adjust the pH to desired value as the
dosage form passes along the GIT and permit drug dissolution and release at a constant
rate independent of GI pH.

19. 2. DELAYED TRANSIT AND CONTINUOUS
RELEASE SYSTEM.
 These systems are designed to prolong release of drug with increased residence
time in GIT. Such dosage forms are designed to remain in the stomach.
 Therefore the drug presented in such systems should be stable at gastric pH.
This class includes following systems
 a) Altered density system
 b) Mucoadhesive or Bioadhesive system
 c) Size based system

20.  A.ALTERED DENSITY SYSTEMi.
If the residence time of drug in the stomach or intestine is prolonged in
some way, the frequency of dosing can be further reduced.
Altering the density of drug particle, use of mucoadhesive polymers and
altering the size of the dosage form.
A. High -density pellets
B. Low -density pellets
B. MUCOADHESIVE SYSTEM
A mucoadhesive or bio adhesive polymer cross- linked polyacrylic acid,
when incorporated in a tablet , allow it to adhere to the gastric mucosa or
epithelium.
C. SIZE- BASED SYSTEM
The diameter of tablet always greater than 2 cm which cannot pass
through pylorus and cannot goes into intestine. Using high grade polymer
like HPMC K200 having high swelling property.

21. 3. Delayed release system
These systems are fabricated to release the drug only at specific site in
the GIT.
The drugs those are-
 Destroyed in stomach or by intestinal enzymes
 Known to cause gastric irritation
 Absorbed from specific site in intestine are formulated in such systems.
The two types of delayed release systems are
 Intestinal release system
 Colonic release system

22.  Intestinal release system
A drug may be coated for intestinal release for several known reason to
prevent gastric irritation, destabilization in gastric pH.
 Colonic release system
Drug are poorly absorbed through colon but may be delivered to such a site
for two reason-
 Local action as in the treatment of ulcerative colitis.
 Systemic absorption of protein and peptide drug like insulin and vasopressin.

23. Evaluation of SR and CR tablets
 Appearance
 Friability
 Hardness
 Thickness
 Weight variation
 Tablet density
 Drug content
 In- vitro drug release
 In – vivo study
 Diffusion study
 Stability study
 Bioadhesion or mucoadhesion test
 IVIVC
 Floating capability
 Kinetic modeling

24. APPLICATION OF SR AND CRDDS
 Oral controlled drug delivery system
 GRDDS
 Ocular drug delivery system
 Transdermal drug delivery system
 Intestinal drug delivery system
 Colonic drug delivery system

25. Marketed product

26. CONCLUSION
 The sustained release drug delivery system is very helpful in
increasing the efficiency of the dose, safety of dose as well as the
patient compliance.
 The controlled release drug delivery system aims to release the
drug at the desired rate over extended period of time to maintain
the therapeutic level in blood.

27. REFERENCES
 Brahamnkar D.M. and Jaiswal S.B.(2010), Biopharmacutics and
pharmacokinetics a Treatise.Delhi, Vallabh Prakashan, 2nd edition
,pp.397-463.
 Dr. Dheeraj T. Baviskar and Dr. Dinesh K.Jain, Novel drug
delivery system, Nirali prakashan, 3rd edition(2016),pp.2.1-2.31 .
 C.V.S Subramanyam, Textbook of biopharmaceutics and
pharmacokinetic, Vallabh prakashan, 2nd edition ( 2015) ,pp.262-
284 .