Osmotic activated drug delivery system

OSMOTIC ACTIVATED DRUG DELIVERY SYSTEM
MEHAK AGGARWAL
M.PHARM (PHARMACEUTICS)
HIMACHAL INSTITUTE OF PHARMACY

CONTENT
 Introduction
 Advantages
 Disadvantages
 Basic components of ODDS
 Osmotic pumps

INTRODUCTION
 Osmotic pressure is used as the driving force for osmotic to release the drug in a controlled manner.
 Osmotic controlled drug delivery system generally consists of a core including the drug an osmotic
agent, excipients and semipermeable membrane coat.
 Osmotic pressure gives zero order drug delivery which is driven force for release of drug from dosage
form. Osmotic semipermeable (electively permeable) membrane driven by a difference in solute
concentration controlled drug delivery system worked on the principle osmosis i.e. movement of water
across; across the membrane which create difference in osmotic pressure across the membrane.
 Osmotic drug delivery systems (ODDS) is driven by an osmotic gradient differ from diffusion systems
that active agent are deliver by concentration of drug in the device.

ADVANTAGES
 ODDS gives zero order release profile after an initial lag.
 Drug release mechanisms are independent or its concentration which is advantageous for sustained
release.
 Drug release is independent of gastric pH, GI motility and hydrodynamic condition.
 ODDS release drug in highly predictable rate.
 Odds can be delayed causing decrease dosing frequency and improve patient compliance.

DISADVANTAGES
 There is risk of dose dumping.
 Special equipment is required for making orifice in the system.
 Special equipment requirement makes it less economical.
 ODDS create rapid development of tolerance.

BASIC COMPONENTS OF ODDS
1. DRUG- Drug should have short half life (2-6hr), highly potent and used for prolonged treatment.
Solubility of drug should be moderate. Examples are- diltiazem HCl, Metoprolol, Nifedipine, Verapamil,
Glipizide.
2. OSMOTIC AGENT- Also called osmogens or osmogents.
 It is responsible for creating osmotic pressure inside the system.
 If solubility of drug is low then the drug will show slow rate zero order release.
 They enhance the release rate by creating very high osmotic pressure gradient inside the system.

Types of Osmotic Agents
Water soluble salts of
inorganic acids
• Magnesium chloride
• Potassium chloride
• Sodium chloride
Water soluble salts of
organic acids
• Potassium acetate
• Magnesium succinate
• Sodium benzoate
• Sodium citrate
Carbohydrates
• Mannose
• Sucrose
• Maltose
• Lactose

SEMI-PERMEABLE MEMBRANE
 It is made up of polymer that is permeable to water but impermeable to solute (drug and excipients).
 These polymers are cellulose esters, cellulose ethers and eudragits.
 Semi-permeable membrane must have sufficient wet strength and wet molecule so that it retain its
dimensional integrity throughout the operational lifetime of the device.

OSMOTIC PUMPS-
1. SINGLE CHAMBER OSMOTIC PUMP(ELEMENTARY OP)
 Elementary osmotic pump contained osmotic core consist of drug with or without an osmogenes. Then
coated with a semipermeable membrane (SPM) and a small orifice is created in the membrane for
release of drug solution.
 When such a system is swallowed water from the GIT enters through the SPM when come in contact
with GI fluid because of the osmotic pressure gradient and forms a saturated solution inside the device.
 Water enter continues at a constant rate until the entire solid drug inside the tablet has been dissolved.
Drug continues to be delivered at a declining rate until the osmotic pressure between outside
environment and saturated drug solution getting nearly same.
 The elementary osmotic pump delivers 60 - 80% of its drug content at a constant rate. There is a short
lag time of 30- 60 min since the system hydrates before zero order drug release from the elementary
osmotic pump is obtained.

 Elementary osmotic pump are mostly suitable for moderate water soluble drug. Factors which affecting
the release rate from elementary osmotic pump are membrane thickness, osmotic pressure, type of
membrane and characteristics, solubility, size of the delivery orifice.

2. OSMOTIC PUMP WITH NON-EXPANDING SECOND CHAMBER
 It is multiple chamber device containing non-expanding second chamber.
 Depending upon the function of second chamber, it is divided into two sub-groups.
 Purpose of second chamber is either dilution of drug solution exit or immediate delivery of two drugs.

3. MULTIPLE-CHAMBER OSMOTIC PUMP PUSH-PULL OSMOTIC
PUMP (PPOP)
 It consists of two compartments, which are separated by an elastic diaphragm.
 Upper compartment is the drug compartment and lower compartment is used as push compartment.
 Upper compartment has orifice to deliver drug outside the pump.
 When device comes in contact with water, both compartments are imbibed by water.
 No orifice is present in the lower compartment, osmotic agent in layer simultaneously attract water and
pushes diaphragm into the upper chamber and deliver drug solution via delivery orifice.

SANDWICHED OSMOTIC TABLETS (SOTS)
 They have two delivery orifices, each for two drug layers and between these layers polymeric push layer
is sandwiched.
 When this system is placed in aqueous environment, the middle push layer containing swelling agent
sells and drug is released from two orifices situated in opposite sides of tablet.
 Because of this SOTS are applicable for drugs which are prove to cause local irritation of gastric mucosa.

SANDWICHED OSMOTIC TABLETS (SOTS)

4. MODIFIED OSMOTIC PUMPS CONTROLLED POROSITY OSMOTIC
PUMPS (CPOP)
 CPOP contains core filled with water soluble additives and drug which coated with asymmetric structure
membrane.
 Membrane is semipermeable and insensitive pore forming additive, like sodium chloride, urea, and
potassium chloride, mannitol, and sorbitol, dispersed throughout the wall.
 CPOP when come in contact with aqueous environment dissolved water soluble additive from
membrane are leached out forms permeable to water. as controlled water. It forms sponge like
structure, act as microporous membrane and release of drug takes place through these micro porous
channels.
 The release rate of drug delivery is dependent on the coating thickness, level of soluble components in
the coating, permeability of the semi permeable membrane, solubility of the drug in the tablet core, and
osmotic pressure difference across the membrane, total surface area of coating. The release rate of drug
delivery is not affected by the pH and agitation of the release media.
 CPOP reduces stomach irritation problem by releasing drug from whole surface of device.

6. LIQUID OROS CONTROLLED RELEASE SYSTEM (L-OROS)
 They are designed to deliver drugs as liquid formulation and combine the benefits of extended release
with high bioavailability.
3 types of system
L-OROS hard cap-
Made up of hard gelatin
capsule with two parts i.e.,
liquid drug layer and an
osmotic engine coated with
SPM.
L-OROS soft cap-
Made up of soft gelatin
capsule enclosed in barrier
layer (osmotic layer)
Delayed liquid bolus delivery
system-
It is in capsule shaped device
and deliver pulse of liquid
drug.

Liquid OROS controlled release system (L-OROS)

REFERENCES
• Ali N., (2021), Review article on osmotic drug delivery system,
http://dx.doi.org/10.13140/RG.2.2.13449.77920.
• Syed SM., (2015), Osmotic drug delivery system, International journal of pharmaceutical research and
allied science, 4(3), 10-20.
• Keraliya RA., Patel C., Patel P., Keraliya V., Soni TG., Patel RC., Patel MM., (2012), Osmotic drug delivery
system as a part of modified release dosage form, ISRN Pharm.,
http://dx.doi.org/10.13140/RG.2.2.13449.77920.
• Gupta RN., Gupta R., Basniwal P., Rathore GS., (2010), Osmotically controlled oral drug delivery systems:
a review, International journal of pharmaceutical sciences, 1(2), 269-275.
• Khatri N., Nikram S., Bilandi A., (2016), Oral osmotic drug delivery system: a review, International journal
of pharmaceutical sciences and research, 2302-2312. 10.13040/IJPSR.0975-8232.7(6).2302-12

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