Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Liposomes
Patent
1990-06-08
1995-04-04
Henley, III, Raymond
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Liposomes
514 78, 514825, A61K 3722, A61K 31685
Patent
active
054035929
DESCRIPTION:
BRIEF SUMMARY
This invention relates to lubricant compositions and in particular, compositions adapted for physiological use such as the lubrication of joints.
In man and other animals it is known that synovial fluid acts to effectively lubricate the surfaces of bones that are in frictional contact to form joints. Moreover, the synovial fluid is able to provide effective lubrication in joints such as the human knee, where the normal applied load is about 3 kg. cm.sup.-2.
Due to the widespread and debilitating effects of osteoarthritis and other rheumatic diseases, considerable attention has been paid to developing a lubricant effective for irrigating arthritic joints. Such a lubricant would help to keep the joint mobile and reduce mechanical stress causing pain during movement. Additionally, the lubricant would desirably:
1. reduce wear of the articular surfaces;
2. facilitate release of surfaces in initiating motion; and
3. render the surfaces hydrophobic and, hence, less permeable to fluid whose expression from the joint can contribute to the hydration of cartilage which is a common finding in arthritis.
It is to be noted that a lubricant of the aforementioned type would also be effective in other tissues where surfaces are in sliding contact such as the heart, lungs and in muscle fibres.
Accordingly, attention has been directed towards identifying an "active ingredient" present in synovial fluid that is able to effectively lubricate joints.
It has been recognised that one of the major components of synovial fluid is hyaluronic acid, which has a co-efficient of kinetic friction below 0.02. However, its lubricating ability fails when it is loaded above about 0.5-1 kg. cm.sup.-2. It would therefore fail well below the normal load of about 3 kg. cm.sup.-2 borne by the knee joints of man.
The finding of the failure of hyaluronic acid to effectively lubricate under such loads has raised the question as to the nature of the surface active ingredient which would normally be present in a joint rendering the articular surfaces of the joint hydrophobic.
It has further been observed that good lubrication of joints is achieved when synovial fluid is replaced by saline thus suggesting that the active ingredient is adsorbed onto the articular surfaces.
In studying the sliding of the pleural surfaces in the lung, the present inventor found phospholipids in pleural fluid and has shown that phospholipids can lubricate well as a layer adsorbed to such surfaces as glass or quartz when deposited onto those surfaces from solution in chloroform. Further, studies showed that these layers had high-load-bearing properties and that the same phospholipids are present in many other fluids adjacent to sliding tissue surfaces, for example, the pericardium, numerous visceral surfaces and the joints. Moreover, they are present in a surface active state which would be needed for them to be adsorbed to the sliding surfaces in vivo.
The results of those experiments have shown that layers of certain phospholipids, especially the disaturated phosphatidylcholines (lecithins), can give coefficients of kinetic friction of less than 0.01 and sometimes as low as 0.002 when deposited by evaporation from solution in chloroform. Moreover, such low values for coefficient of kinetic friction may be obtained for loads as high as 13 kg. cm.sup.-2. These findings may explain why joint lubrication has the characteristics of boundary lubrication and yet coefficients of friction of a magnitude generally associated with hydrodynamic lubrication.
The present inventor has found that a composition having-a suitably low coefficient of kinetic friction of the order of 0.003-0.010 may be prepared by the ultrasonication of surface active phospholipid in saline to produce a suspension of liposomes. It has further been found that lower coefficients of kinetic friction may be obtained when a surface active phospholipid is suspended in hyaluronia acid. Such compositions give suitably low coefficients of kinetic friction at relatively high loads.
The present invention relates to a l
REFERENCES:
patent: 4427649 (1984-01-01), Dingle et al.
patent: 4937254 (1990-06-01), Sheffield et al.
patent: 4946683 (1990-08-01), Forssen
Henley III Raymond
Macnaught Pty Limited
Weddington K.
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