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Techniques And Methods For Liposome Manufacturing

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.

Phospholipids like lecithin is used as raw material. The phospholipid molecules have heads that love water. They also have two tails that are essential fatty acid chains repelled by water. When the phospholipids are put in a solution that is water-based, the heads end up side by side with the tails trailing behind. The fact that the tails repel water means that another layer lines up with the tails facing the tails of the first layer. This natural alignment results in two rows of tightly fitting molecules. These layers form membranes around and inside all cells.

Liposomes can be used as delivery vehicles for a wide variety of drugs, vaccines, enzymes, genetic material and for some nutritional supplements as well. They not only allow for release of encapsulated materials but are beneficial in themselves for cells. The lipids used to construct the fatty part of the molecule is used by the cell wall for repair and construction of new membranes.

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.

All the methods for preparation of liposomes have the same basic stages. Lipid vesicles are formed when thin lipid films are hydrated. The liquid bilayers become fluid, detach and self-close to form large vesicles. Once these large particles have formed, their size is reduced by energy input. This may be in the form of sonic energy called sonication or mechanical energy called 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.

A great benefit involved in using liposomes is that they can be customized for different applications by varying the method of preparation, size, lipid content and surface charge. Many conventional techniques for preparing them and reducing their size are fairly simple to implement and equipment does not have to be too sophisticated. However, novel routes are being discovered for preparation due to motivation to scale-down for point-of-care applications or or to scale-up for industrial applications.




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