Osmotic drug delivery systems utilize the principle of osmotic pressure to deliver drugs in a controlled manner independent of physiological parameters like pH. They have advantages like predictable release rates and minimal effects of food. Some types of osmotic systems include implantable pumps like Rose and Nelson pump and oral osmotic pumps. Factors affecting drug release from these systems include the drug's solubility, osmotic pressure inside the system, characteristics of the delivery orifice, and properties of the semipermeable membrane.

1. BY:KOMAL RAO
M.PHARM 1ST YEAR(Pharmaceutics)
2004610001

2. OSMOTIC DRUG DELIVERY SYSTEMS
Osmosis-Osmosis can be defined as the net movement of water across a
selectively permeable membrane driven by a difference in osmotic pressure
across the membrane.
• It is driven by a difference in solute concentrations across the membrane that
allows passage of water, but rejects most solute molecules or ions.
• Osmotic systems utilize the principle of osmotic pressure for the delivery of
drugs.
• Drugs release from these systems is independent of pH and other physiological
parameter.

3. • Osmotic drug delivery uses the osmotic pressure of drug or other solutes
(osmogens or osmagents) for controlled delivery of drugs. Osmotic drug
delivery has come a long way since Australian physiologists Rose and
Nelson developed an implantable pump in 1955.
ADVANTAGES
• 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.
• A high degree of in vivo—in vitro correlation (IVIVC) is obtained in osmotic
systems because the factors that are responsible for causing differences in
release profile in vitro and in vivo (e.g., agitation, satiable pH) affect these
systems to a much lesser extent.

4. • The release from osmotic systems is minimally affected by the presence of
food in the gastrointestinal tract (GIT). This advantage is attributed to design
of osmotic systems. Environmental contents do not gain access to the drug
until the drug has been delivered out of the device.
• Production scale up is easy.
DISADVANTAGES
• Expensive
• Chance of toxicity due to dose dumping
• Rapid development of tolerance
• Hypersensitivity reaction may occur
• Integrity and consistency are difficult

5. OSMOGEN / OSMAGENT / OSMOTIC DRIVING AGENT
• For the selection of osmogen, the two most critical properties to be considered
are osmotic activity and aqueous solubility.
• Osmotic agents are classified as,
• Inorganic water soluble osmogen: Magnesium sulphate, Sodium chloride,
Sodium sulpahte, Potassium chloride, Sodium bicarbonate etc. • Organic
polymeric osmogen: Na CMC, HPMC, HEMC, etc
• Organic water soluble osmogen: Sorbitol, Mannitol,etc.

6. CLASSIFICATION OF OSMOTIC DRUG DELIVERY
SYSTEM
 Implantable-
1. The Rose and Nelson Pump
2. Higuchi Leeper Pump
3. Higuchi Theuwes Pump
Oral Osmotic Pump Single Chamber Osmotic Pump- Elementary Osmotic Pump
Multi Chamber Osmotic Pump
- Push Pull Osmotic Pump
Osmotic Pump with non expanding second chamber.
- Controlled Porosity Osmotic Pump
Osmotic bursting osmotic pump
Monolithic Osmotic System .

7. THE ROSE AND NELSON PUMP

8. • The first osmotic pump developed in 1955 for the delivery of drugs to the
sheep and cattle gut.
• Composed of three chambers.
• Water to be loaded prior to use was the drawbacks of rose nelson osmotic
pump.
• The difference in osmotic pressure across the membrane moves water from
the water chamber in to the salt chamber.
• The volume of chamber increases because of this water flow, which distends
the latex diaphragm separating the salt and drug chambers, thereby pumping
drug out of the device.

9. THE HIGUCHI LEEPER PUMP

10. • It has no water chamber, and the activation of the device occurs after
imbibition of the water from surrounding environment.
• It has a rigid housing.
• Widely employed for veterinary use. It is either swallowed or implanted in
body of an animal for delivery of antibiotics or growth hormones to animal.

11. THE HIGUCHI THEUWES PUMP

12. • In this device, the rigid housing is consisted of a semi permeable membrane.
The drug is loaded in the device only prior to its application, which extends
advantage for storage of the device for longer duration.
• The release of the drug from the device is governed by the salt used in the
salt chamber and the permeability characteristics of outer membrane.
• Diffusional loss of the drug from the device is minimized by making the
delivery port in shape of a long thin tube
• It is simpler than higuchi-leeper osmotic pump.

13. ELEMENTARY ORAL OSMOTIC PUMP
1.Major method of achieving controlled drug release.
2. The EOP was developed by Alza under the name OROS for controlled
release oral drug delivery formulations.

14. PUSH PULL OSMOTIC PUMP

15. • It is modified EOP & used for drugs with very poor water solubility & also for
highly water soluble drugs.
• They contain two or three compartment separated by elastic diaphragm
• Upper compartment contain drug with or without osmogen (drug
compartment nearly 60 — 80 %) and lower compartment (Push
compartment) contain Osmogen at 20 — 40 %.
• It is similar to bilayer coated tablet- Upper & Lower layer
• Tablet core is coated by using standerd film coating equipment with a
semipermeable membrane.

16. CONTROLLED POROSITY OSMOTIC PUMP

17. • Orifice is not present in this pump.
• It consist of two layers of membrane.
• The inner membrane is micro porous containing water soluble pore forming
agent.
• A semi-permeable membrane covers this layer.
• When the system is placed in an aqueous environment the soluble
components of first layer of coating dissolve, resulting in a microporous ,
which provides greater flux of water into the system.

18. OSMOTIC BURSTING OSMOTIC PUMP

19. • In this system delivery orifice is absent and size is small . When it is placed in
an aqueous environment, water is imbibed and hydraulic pressure is built up
inside until the wall rupture and the content are released to the environment.
• Varying the thickness as well as the area the semipermeable membrane can
control release of drug. This system is useful to provide pulsated release.
• Core: API ± osmogents
• Coat: Semi permeable membrane without delivery orifice

20. Factors Affecting Release of Medicament from osmotic
DDS
 Solubility
 Osmotic Pressure
 Delivery Orifice
 Membrane Type

21. A. Solubility
• Solubility of drug is one of the most important factors since kinetic of osmotic
release is directly related to the drug solubility.
• Drug with density of unity and solubility less than 0.05 g / cm3 would release greater
than or equals to 95 % by zero order kinetics
• Drug with density ≥ 0.3 g / cm3 solubility would demonstrate with higher release rate
≥ 70 % by zero order.
• Both highly soluble and poorly soluble drugs are not good candidates for osmotic
drug delivery

22. B. Osmotic pressure
• The next release-controlling factor that must be optimized is the osmotic
pressure gradient between inside the compartment and the external
environment
• The simplest and most predictable way to achieve a constant osmotic
pressure is to maintain a saturated solution of osmotic agent in the
compartment
• The release rate of a drug from an osmotic system is directly proportional to
the osmotic pressure of the core formulation

23. C. Delivery orifice
• To achieve an optimal zero order delivery profile, the cross sectional area of
the orifice must be smaller than a maximum size to minimize drug delivery by
diffusion through the orifice
• Furthermore, the area must be sufficiently large, above a minimum size to
minimize hydrostatic pressure build up in the system
• The typical orifice size in osmotic pumps ranges from 600micron to 1 mm.

24. D. Membrane type
• Type and nature of polymer
-polymer that is permeable to water but impermeable to solute can be selected
Examples- cellulose esters such as cellulose acetate, cellulose diacetate,
cellulose triacetate, cellulose propionate, cellulose acetate butyrate Membrane
thickness.
• Release rate from osmotic systems is inversely proportional to membrane
thickness .