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Dear bloggers

First of all I want to wish you Happy Pharmacy week in advance.

In our college we are planning to celebrate in order to create awareness in the society as well in the students regarding the importance of the pharmacy profession.

I am also participating actively along with my learners.

Here I want to present my blog on the Osmotic drug Delivery.


Right from many decades the treatment for an acute (or) a chronic health problems is being carried out mostly by the drug delivery to the patients by using different types and novel types of pharmaceutical dosage forms. Traditional drug delivery systems have less management on drug release. At present, pharmaceutical research has lead to the upliftment of several novel drug delivery systems.

The release of the drug can be controlled by various ways and the recent approaches are based on the use of the matrix or by osmotic phenomenon. (1)


The mechanism of the osmosis is substances move from higher concentration area to the lower concentration area. Semipermeable membrane is the one which allows only the solvent particles to move through but not the solute particles and this phenomenon is called osmosis. Osmotic pressure is nothing but the pressure higher than the solvent in pure form, and when same amount of pressure is applied then the solvent particles cannot pass through the semipermeable membrane. (2)


The credit of introducing the osmotic effect goes to Abbe Nollet (3). Pfeffer, in 1877, with the help of the semipermeable membrane separated sugar solution from water. He postulated that directproportionality is present between the osmotic pressure and concentration,temperature. Vant Hoff and Morse gave the equation pV = n RT (3).


Osmotic drug delivery has following advantages than the oral which took our attention on these drug delivery systems.

1. By osmotically controlled drug delivery, we can achieve zero order kinetics.

2 osmotically controlled drug delivery systems gives greater drug release rates over the conventional dosage forms.

3. The drug released does not depend on the gastric pH in case of the oral osmotic systems.

4. The presence of the food does not affect the drug release to much extent.

5. We an get high vivo- in vitro correlation (IVIVC) by these systems.


1. Cost is more.

2. Film defects may occur if the coating process in not managed properly, that eventually leads to dumping.

3.Decreased capacity to adjust the dose.


Drug :

All varieties of drugs are not be apt for the osmotic system for the extension of the therapeutic action of the given medication. Drug which possesses half-life ranging from 1-6hrs and extended cure for the diseases are the best applicants here. Drugs like Metoprolol, Oxprenolol, Nifedipine, Diltiazem HCl, Carbamazepine, Glipizide etc. are choosen in the osmotic drug delivery.

Semi permeable membrane:

Semi permeable membranes can be made of number of polymers. The selection of polymers depends on solubility, the amount of the drug that has to be released and the rate too. Most frequently Cellulose acetate is used. This semipermeable membrane must acquire the following qualities.


In the device the pressure is generated and this should have capacity to withhold it.


Should posse's required wet strength and permeability.


Should be compatible with the body


It should not swell.


Plasticizers have an important role in the film coating formation. Plasticizers will elevate the flexibility, and permeability of the fluids. Plasticizers that are generally used are: Polyethylene glycols, Diethyl tartarate or Diacetin, Glycerolate,
myristates, Ethylene glycol monoacetate; and diacetate-for low permeability, Tri ethyl citrate Glycolate, for more permeable film formation.

Osmotic agent

osmotic agents or Osmogens are the most important constituents of osmotic pump, generally ionic compounds that consists of either the inorganic salts or carbohydrates and hydrophilic polymers. Many types of osmogens that are used are Sodium bicarbonate, MgSo4, Sodiumchloride, Potassiumchloride, Sodiumcarboxymethylcellulose, Sodium sulphate, etc.

Wicking agent

These are essential in order to increases the area of interaction between the drug and the fluids coming in. By using these, the rate of drug release from the orifice will be increased. examples are colloidal silicon dioxide, PVP & Sodium laurylsulphate,kaolin,alumina etc.

Pore former

These are used in the preparation of pumps for drugs that are less water soluble. They help in the development of microporous membrane. Examples are: Alkaline earth metals, salts like NaCl , Kcl, Carbohydrates like sucrose, lactose, glucose.

Coating solvents

To dissolve (or) disperse the polymer and additives, and coat on the substrate surface is the main (or) the primary function of the solvent system. Polymer should be soluble in the solvent to the complete extent; the resistance to the flow should be less, should not be toxic, should have no taste or color and should be evaporated easily.

Examples of solvents used are: Methylene chloride, iso propyl alcohol,methanol, di-chloromethane, ethyl acetate, acetone


1. Osmotic drug delivery system current scenario by
R.S.Thakor,F.D.Majumdar,J.K.Patel & G.C.Rajput ,Journal of pharmacy research vol-3.Issue-4 april 2000 page no:771

2. A review on osmotically regulated devices by
G.Piyush,R.Pankaj,A.Dabeer,A.Ayaj, International journal of pharmacy and life sciences (IJPLS), I(6):302-310
3.Advances in controlled and novel drug delivery by N.K.Jain, CBS publishers, 2008, page no:19
4.Drug delivery through osmotic systems-An overview by T.Ghosh,A.Ghosh, Journal of applied pharmaceutical sciences 01(2):2011:41,42

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