By Jody Leach


The discovery of liposomes with their many interesting properties has attracted much attention. These tiny spheres are suitable for using as delivery vehicles for nutrients and drugs into the human body. Identical to human cell membranes, they easily transfer and deliver active ingredients. Liposome manufacturing involves the same basic steps but the use many different techniques. Research is constantly being done to increase their effectiveness.

When phosphlipids such as lecithin come into contact with water, an interesting effect occurs. The molecules consist of a head which loves water and two tails that repel it. This means that the heads all face one side and the tails the other. Another layer is formed with tails all facing the tails of the first later and the heads facing the other way. These layers form the membranes around and inside every cell of the human body.

Liposomes are used to deliver toxic drugs to target cancer cells. They are used for delivering nutrients deficient in the body or cosmetic nutrients to the skin. Many other medical applications are possible too such as in the field of genetics. Preparation methods depend on various factors such as the characteristics of the material to be carried, the consistency offered from batch to batch and scale of production.

The tiny size of liposomes means they are quickly assimilated into the bloodstream for delivery throughout the body. The payload is biologically inert until it is delivered to needy cells. They are all basically the same but the differences between them occur in the way they are released, how long this takes as well as where and why this occurs.

The methods used in preparation may all be quite different but the basic stages remain the same. Thin lipid films are hydrated and this causes liquid bilayers to form. These large vesicles need to be reduced in size and energy output is required for this. Sonication is the use of sound waves and another mechanical method used is extrusion.

So, the general elements consist of lipid preparation for hydration, hydration with agitation and then sizing of vesicles. Each different method used has certain advantages and disadvantages. Liquid hydration methods usually result in low dose loading. Sonication can affect the structure of an encapsulated drug.

Some of the problems that have to be faced are structural instability, inconsistency in size and expensive production costs. Liposomal delivery systems are still in the experimental stage. The precise ways in which they act within the body are being carefully studied as well as ways in which they can be made to target diseased tissue or a specific organ.

One of the greatest benefits of liposomes is there flexibility. They can be adapted in many different ways to suit different applications. Size, surface charge and lipid content can all be varied according to the techniques used. Conventional methods are effective but much experimentation is still being done. The future holds many new possibilities with the exciting developments taking place in this field.




About the Author:



0 comments :