Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Liposomes
Patent
1995-09-22
1998-06-30
Bawa, Raj
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Liposomes
424 7802, 424531, 514937, A61K 9107
Patent
active
057730261
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a substantially non-toxic water dispersible therapeutic formulation including a substantially water insoluble therapeutic agent selected from the group consisting of carotenoid compositions and tocopherols that can be administered to animals, including humans, by injection or intravenously into the organs, blood stream or lymph.
BACKGROUND OF THE INVENTION
Some chemical compounds of physiological therapeutic significance have little or no water solubility. The water insolubility of these compositions limits the means by which those compounds can be administered to the body.
Included in the group of compounds that are considered to be of physiological importance are the carotenoids, tocopherols and other lipid based molecules used for various therapeutic purposes.
It has been hypothesised that carotenoids and in particular beta-carotene may reduce the risk of breast, lung, colon, prostate and cervical cancer, heart disease and stroke and may retard macular degeneration. In this respect, one hypothesis is that in mammals beta-carotene is converted to vitamin A and vitamin A analogues or retinoids (see Moon RC: Comparative aspects of carotenoids and retinoids as chemopreventive agents for cancer. J Nutr 119:127-134, 1989). It is this pro-vitamin A activity and the ability to prevent oxidative damage that has made carotenoids and in particular beta-carotene a compound of interest in chemopreventive studies. For instance, anti-oxidants are used, amongst other things, to quench free radicals that are by-products of normal metabolism in cells.
Beta-carotene has also been used in the treatment of erythropoietic protoporphyria (EPP). EPP is a genetic disease causing an inadequacy in the metabolism of porphyrin compounds. It results in a rapid blistering of the skin on exposure to sunlight.
When considering the use of these lipid based compositions for human application immediate difficulties arise because of their lipophyllic nature which renders them insoluble in water in useful quantities. It is believed that these products are transported in the bloodstream as low density lipoproteins.
The current principal means by which these therapeutic compositions are introduced into the body is orally. However, this method is often unsatisfactory because the poor absorption of these compositions by the alimentary canal limits the concentrations in the blood which can be achieved. Further, there will be a substantial delay before a required level of these compositions in the bloodstream or a specific organ is reached. Sometimes the required level cannot be reached as certain individuals do not absorb carotenoids, especially beta-carotene, very well. There is about a tenfold difference in the ability of human individuals to absorb beta-carotene. There have been over 500 carotenoids isolated, but only approximately 15 have been shown to occur in the bloodstream.
Physicians often seek to administer compounds by injection or by intravenous drip rather than oral ingestion. However, because of the virtual water insolubility of these therapeutic compositions it is very difficult to administer them either by injection or intravenously. Consequently, the compound must be made dispersible in an aqueous base so that it is available to the body's cells. In this regard, the base must be compatible with, for example, the bloodstream or lymph, and the material must be prepared in a biologically sterile form. The base must itself be non-toxic to the human cells.
To date several in vitro studies have taken place to determine the effect of beta-carotene on normal and transformed cell types using solvents to solubilise the beta-carotene such as tetrahydrofuran, butanol, chloroform, hexane, dimethylsulfoxide, ethanol or in a liposome micelle. Previous liposome preparations have shown toxicity in cell line cultures as well as being limited in application. (see Bertram J.S., Pung A, Churley M., et al: Diverse carotenoids protect against chemically induced neoplastic transformation. Carcinogenes
REFERENCES:
patent: 4572915 (1986-02-01), Crooks
patent: 4680314 (1987-07-01), Nonomura
Bawa Raj
Betatene Limited
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