The document discusses osmotic drug delivery systems (ODDS). It begins by defining osmosis and describing how osmotic pressure drives the movement of water across a semi-permeable membrane. It then discusses the advantages of ODDS such as zero-order delivery kinetics and independence from gastric pH. The document classifies several types of ODDS including elementary osmotic pumps, controlled porosity pumps, and push-pull pumps. It also describes components like the semi-permeable membrane and osmotic agents. In vitro evaluation methods and factors affecting ODDS performance are briefly covered.

1. OSMOTIC DDS

2. INTRODUCTION
 Osmosis refers to the process of movement of solvent from lower
concentration of solute towards higher concentration of solute
across a semi permeable membrane till the equilibrium achieved.
 Osmotic pressure is the pressure which, if applied to the more
concentrated solution, would prevent transport of water across the
semipermeable membrane.
2

3. INTRODUCTION
Π = p c RT
Where,
 p = Osmotic pressure
 Π = osmotic coefficient
 c = molar concentration
 R = gas constant
 T = Absolute temperature
3

5. ADVANTAGES
 The delivery rate of zero-order is achievable with osmotic systems.
 Delivery may be delayed or pulsed, if desired.
 Higher release rates are possible with osmotic systems compared
with conventional diffusion-controlled drug delivery systems.
 The release rate of osmotic systems is highly predictable and can be
programmed by modulating the release control parameters.
 For oral osmotic systems, drug release is independent of gastric pH
and hydrodynamic conditions.
 The release from osmotic systems is minimally affected by the
presence of food in gastrointestinal tract.
 A high degree of in vivo- in vitro correlation (IVIVC) is obtained
in osmotic systems.
5

6. DISADVANTAGES
6
Osmotic system

7. CLASSIFICATION
7
Single
osmotic pump
Elemantary
osmotic pump
(EOP)
Controlled
porosity
osmotic pump
Osmotic
bursting
osmotic pump
Multi-chamber
osmotic pump
Push pull
osmotic pump
(PPOP)
Sandwich
osmotic
tablets (SOTS)
Oral osmotic
capsules
OROS- CT
L- OROS
Pelleted delayed
release
Assymetric
membrane capsule
Telescopic capsule
for delayed release
Implantable
osmotic system
DUROS
osmotic
pump
ALZET
osmotic
pump
Oral osmotic tablet

8. CRITERIA FOR SELECTION OF A DRUG
 Short biological Half-life (2- 6 hrs)
 High potency
 Required for prolonged treatment
 (e.g: Nifedipine, Glipizide, Verapamil and Chlorpromazine
hydrochloride).
8

9. BASIC COMPONENTS
 Drug
 Osmotic agent
 Semipermeable membrane
 Coating material
 Hyrophilic and hydrophobic polymers
 Wicking agents
 Pore forming agents
9

10. OSMOTIC AGENTS
 Osmotic pressures for concentrated solution of soluble solutes
commonly used in controlled release formulations are extremely
high, ranging from 30 atm for sodium phosphate up to 500 atm for a
lactose-fructose mixture.
 These osmotic pressures can produce high water flows across
semipermeable membranes .
10

11. OSMOTIC AGENTS
 The osmotic water flow across a membrane is given by the equation,
dv/dt = Aθ∆π
l
 Where,
dv/dt, is the rate of water flow across the membrane of area A,
thickness l, permeability θ in cm3, and ∆π.
11

12. OSMOTIC PRESSURE OF SATURATED SOLUTIONS OF COMMONLY
USED PHARMACEUTICAL SOLUTES
12

13. OSMOTIC PRESSURE OF SATURATED SOLUTIONS OF COMMONLY
USED PHARMACEUTICAL SOLUTES
13

14. SEMIPERMEABLE MEMBRANE
 The membrane must possess certain performance criteria such as:
 Sufficient wet strength and water permeability
 Should be biocompatible
 Rigid and non-swelling
 Should be sufficient thick to withstand the pressure within the
device.
 Any polymer that is permeable to water but impermeable to solute
can be used as a coating material in osmotic devices. e.g. Cellulose
esters like cellulose acetate, cellulose acetate butyrate, cellulose
triacetate and ethyl cellulose and Eudragits.
14

15. COATING MATERIAL
 Different types and amount of plasticizers used in coating membrane
also have a significant importance in the formulation
of osmotic systems. They can change visco-elastic behavior of
polymers and these changes may affect the permeability of the
polymeric films. Some of the plasticizers used are as below:
 Polyethylene glycols
 Ethylene glycol monoacetate; and diacetate- for low permeability
 Triethyl citrate
 Diethyl tartarate or Diacetin- for more permeable films
15

16. HYDROPHILIC AND HYDROPHOBIC
POLYMERS
 These polymers are used in the formulation development of osmotic
systems containing matrix core.
 The selection of polymer is based on the solubility of drug as well as
the amount and rate of drug to be released from the pump.
16

17. WICKING AGENTS
 The function of the wicking agent is to draw water to
surfaces inside the core of the tablet, thereby creating
channels or a network of increased surface area.
 Examples are colloidon silicon dioxide, kaolin, titanium
dioxide, alumina, niacinamide, sodium lauryl sulphate
(SLS), low molecular weight polyvinyl pyrrolidone
(PVP), bentonite, magnesium aluminium silicate,
polyester and polyethylene, etc. 17

18. PORE FORMING AGENT
 These agents are particularly used in the pumps
developed for poorly water soluble drug and in the
development of controlled porosity or multiparticulate
osmotic pumps.
 The pore formers can be inorganic or organic and solid
or liquid in nature. Like,
 Alkaline metal salts such as sodium chloride, sodium
bromide, potassium chloride, etc.
 Alkaline earth metals such as calcium chloride and
calcium nitrate
 Carbohydrates such as glucose, fructose, Lactose, etc.
18

19. OSMOTIC PUMP & ITS COMPONENT
19

20. RECENTLY IN USE OSMOTIC PUMP
20
Drug solution leaving via delivery portal
Removable cap
Flow moderator
Semipermeable membrane
Osmotic agent
Flexible impermeable reservoir wall
Reservoir

21. 21
Fig. : EOP
Limitations:
• SPM should be 200-300μm thick to withstand pressure
• Thick coatings lowers the water permeation rate
• Applicable mostly for water soluble drugs
ELEMENTRY OSMOTIC PUMP (EOP)

22. CONTROLLED POROSITY OSMOTIC PUMP
22
It is laser or micro driven orifice. When Controlled Porosity Osmotic
pump is placed in aqueous environment the water soluble component of
coating dissolves and forms micropores in membrane and water diffuses inside
the core through microporous membrane, setting up an osmotic gradiant and
thereby controlling the release of drug.

23. OSMOTIC BURSTING OSMOTIC PUMP
 Core: API ± osmogents
 Coat: Semi permeable membrane without delivery orifice
 When placed in aqueous environment, water is imbibed and
hydraulic pressure is built up inside the system, then wall ruptures
and the contents are released.
 It is used for pulsated release.
23

24. PUSH-PULL OSMOTIC PUMP (PPOP)
 Core Tablet:
 Layer 1: API ± osmogents
 Layer 2: Polymeric osmotic agents
 Coat: Semi permeable membrane with delivery orifice.
 It is a bilayer tablet coated with semi permeable membrane.
 The PPOP system consists of two compartments separated usually
by an elastic diaphragm. The upper compartment contains the drug
and is connected to the outside environment via a small delivery
orifice.
24

25. PUSH-PULL OSMOTIC PUMP (PPOP)
25

26. PUSH-PULL OSMOTIC PUMP (PPOP)
26

27. SANDWICHED OSMOTIC TABLETS (SOTS)
 It is composed of polymeric push layer sandwiched between two
drug layers with two delivery orifices.
 When placed in the aqueous environment the middle push layer
containing the swelling agents, swells and the drug is released from
the delivery orifices.
 Advantage : the drug is released from the two orifices situated on
opposite sides of the tablet
27

28. SANDWICHED OSMOTIC TABLETS (SOTS)
28

29. DUROS OSMOTIC PUMP
29

30. DUROS OSMOTIC PUMP
30
 Design :
 Implantable drug-dispensing osmotic pump, shaped as a small
rod with titanium housing.
 Mechanism : Through osmosis, water from the body is slowly drawn
through the semi-permeable membrane into the pump by osmotic
agent residing in the engine compartment, which expands the
osmotic agent and displaces a piston to dispense small amounts of
drug formulation from the drug reservoir through the orifice.
 Application: Systemic or site-specific administration of a drug

31. DUROS OSMOTIC PUMP
31

32. ALZET OSMOTIC PUMP
32

33. ALZET OSMOTIC PUMP
33
 Design: Empty reservoir within the core of the pump is filled with
the drug or hormone solution to be delivered and is surrounded by
salt chamber with impermeable layer between them.
 Mechanism: Water enters into the salt chamber through
semipermeable membrane and causes compression of flexible
reservoir and delivery of drug solution.
 Application: To deliver drugs, hormones, and other test agents
continuously at controlled rates from one day to six weeks.

34. LIQUID OSMOTIC SYSTEM (L-OROS)
34

35. OROS TRI-LAYER

36. 36
Osmotic
tablet
and
recent
advancement
in
it-
Nidhi
Lathia

37. MARKETED FORMULATIONS
37
Brand name
Efidac 24®
Acutrim ®
Sudafed 24®
Minipress XL®
API
Chlorpheniramine
Phenylpropanolamine
Pseudoephedrine
Prazocine
Manufacturer
Novartis / Pfizer /
Alza
Novartis
McNeil Consumer
Healthcare
Pfizer / Alza

38. MARKETED FORMULATIONS
38
Brand name
Ditropan XL ®
Glucotrol ®
Procardia XL®
Covera HS ®
API
Oxybutynin
chloride
Glipizide
Nifedipine
Verapamil HCl
Manufacturer
Alza
Pfizer / Alza
Pfizer / Alza
Novartis / Alza

39. FACTORS AFFECTING THE PERFORMANCE
OF OSMOTIC DRUG DELIVERY SYSTEM
Physico-chemical properties of the drug
 Solubility
 Solid or liquid
 Viscosity (Liquids)
 Rheological properties
Properties of osmotic agent
 Osmotic pressure difference generated by the agent which
ultimately will decide the water influx and in turn the delivery
of active.
Membrane type and characteristics
 Wet strength
 Water permeability
Size of delivery orifice
Characteristics of the polymer used (e.g. Hydration,
Swelling etc.)

40. IN VITRO EVALUATION
 The in vitro release of drugs from oral osmotic systems
has been evaluated by the conventional USP paddle and
basket type apparatus.
 The dissolution medium is generally distilled water as
well as simulated gastric fluid (for first 2-4 h) and
intestinal fluids (for subsequent hours) have been used.
 The standard specifications, which are followed for the
oral controlled drug delivery systems are equivalently
applicable for oral osmotic pumps.
 In vivo evaluation of oral osmotic systems has been
carried out mostly in dogs. Monkeys can also be used but
in most of the studies the dogs are preferred.

42. QUESTION BANK
 What is ODDS? Why it is required? Enumerate recent advance in
controlled osmotic drug delivery system with their approaches.
 What are ideal properties of semi permeable membrane? Suggest
few materials for this. Wright note on evaluation of osmotic pump.
 Write a note on principle of osmotic drug delivery system.
 Give advantage and disadvantage of osmotic drug delivery system.
 Give name of osmotic pumps. Give detail on elementary osmotic
pump.
42

43. REFERENCES
43
 Gupta Roop, Gupta Rakesh, Basniwal Pawan k, Rathore Garvendras,
Osmotically controlled oral drug delivery systems: a review, int. J. Ph. Sci.,
2009, 1(2), 269-275.
 Gohel M.C Parikh .R.K, Shah. N.Y Osmotic drug delivery- an update,
pharmainfo.net, 2009, 7(2).
 Lachman L., Liberman H. A., Kanig J. L., The theory and practise of
industrial pharmacy. 2nd Edition 1991, Varghese publishing house,
Pg. 455.
 Aulton M. E., pharmaceutics the science of dosage form design. 2nd
Edition 2002, Churchill livingstone, Pg. 38, 39, 74, 304, 417.
 Ajay Babu, M. Prasada Rao, Vijaya Ratna J, Controlled-porosity osmotic
pump tablets-an overview, jprhc.
 Shailesh Sharma. Osmotic controlled drug delivery. Pharmainfo.net. 2008;
6(3).

44.  Y. W. Chien, (2005), Novel Drug Delivery System,
2nd edition, Marcel Dekker,Inc., 1-3, 17-18, 33-36.
 N. K. Jain and S. K. Jain, (1997), Controlled and
novel Drug Delivery, 1st edition, C.B.S. publishers
and distributors, 1-2.
 M. C. Gohel, R. K. Parikh, N.Y. Shah, (2009),
Osmotic Drug Delivery: An Update.
 R. K. Verma, D. M. Krishna and S. Garg, (2002),
Review article on Formulation aspects in the
development of osmotically controlled oral drug
delivery systems, J. Control. Release, 79, 7-27.
 N. S. Parmar S. K. Vyas, N. Vaya, (2003),
Advances in Controlled and Novel Drug Delivery,
CBS publishers, 18-32
44

45.  S. P. Vyas, R. K. Khar, Controlled Drug Delivery
Concepts and Advances, (2001), Vallabh
Prakashan, 170.
 A.G. Thombre, A.R. DeNoto and D.G. Gibbes,
(1999), Delivery of glipizide from asymmetric
membrane capsules using encapsulated excipients,
J. Control. Release, 60, 333-341.
 Partha Gan Chaudhuri, Satya Prakash Singh, A
Review Of Hydrogel-A Novel Drug Delivery
System.
 X. Li and B.R. Osmotic Controlled Drug Delivery
Systems, In: Design of controlled release of drug
delivery systems, McGraw Hill, 203-229.
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