Lipophilic carrier preparations

Details Lipophilic carrier preparations Lipophilic carrier preparations

1996-07-15

1998-02-10

Weddington, Kevin E.

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Liposomes

514546, 514547, 514548, 514549, A61K 9127, A61K 3122, A61K 31225

Patent

active

057166390

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/SE 95/00117 filed Feb. 6, 1995.


TECHNICAL FIELD

This invention relates to lipophilic carrier preparations having a continuous lipid phase, comprising a polar lipid material, in combination with a non-polar lipid and optionally a polar solvent. Said carrier preparation is suitable for use as a carrier for active materials in pharmaceutical compositions, as well as in cosmetical, food and agricultural products.


BACKGROUND OF THE INVENTION

It is a general problem in the pharmaceutical industry to incorporate drugs into lipophilic carriers which are biocompatible and well tolerated by humans. The reason for this is, firstly, the wide range of chemical structures, and therefore properties, of the active components which art to be incorporated, and, secondly, a suitable carrier based on ingredients which makes the carrier sufficiently flexible to incorporate active components with the mentioned wide range of structural variations.
In order to create flexible lipophilic carriers, polar lipids need to be employed, preferably natural membrane lipids for the sake of biocompatibility and safety, and combined with non-polar lipids, such as vegetable oils or sterol esters. At present time the only membrane lipids available are phospholipid materials, mainly derived from soy or egg lecithin or made by synthetic routes. The phospholipids are zwitter-ionic, such as phosphatidylcholine and phosphatidylethanolamine, or negatively charged, such as phosphatidylinositol or phosphatidylglycerol.
Lipophilic carriers may be organised solutions, such as microemulsions or reverse micellar solutions, reverse vesicles or water-in-oil emulsions.
Margarines and spreads are water-in-oil emulsions which may contain as much as 75% by weight of an aqueous phase. The aqueous phase is dispersed in a triglyceride oil, typically a vegetable oil such as rapeseed oil. The aqueous phase normally contains a thickening agent, such as gelatine in order to stabilise the water-rich oil-continuous emulsion. The emulsifier is typically a phospholipid such as soybean phospholipids (soy lecithin). These emulsifiers consist of mixtures of phospholipid classes, such as phosphatidylcholine and phosphatidylethanolamine, which are zwitter-ionic, and phosphatidylinositol, which is ionic. It is a common knowledge that these lecithin emulsifiers are the most utilized natural lipids in preparing stable food emulsions on an industrial scale. It is also well-known that such emulsions suffer from disadvantages and problems which relate to the lecithin emulsifier.


PRIOR ART

There are only a few examples on lipophilic preparations having a continuous lipid phase reported.
WO 92/05771 describes a lipid particle forming matrix of at least two lipid components; one is non-polar and another is amphiphatic and polar. This particle forming matrix, which can contain bioactive materials, spontaneously forms discrete lipid particles when interacting with aqueous systems. The amphiphatic and polar lipid components are said to be bilayer forming and are chosen from phospholipids such as phosphatidylcholine; the non-polar lipids are mono-, di- or triglycerides.
Microemulsion gels comprising lecithin, i.e. phosphatidylcholine, have been described and characterized by P. L. Luisi, see e.g. D. Capitani et al., Langmuir, 1993, Vol. 9, pp. 685-689. Besides the phospholipid, these gels are composed of a small amount of water and an organic solvent, such as alkanes, fatty acid esters and amines. They are also referred to as organogels. The gels may be used as a matrix for transdermal transport of drugs.
The presence of reverse vesicles, the counter structures to normal vesicles, in an oil was first reported by H. Kunieda, see e.g. H. Kunieda et al., Advanced Materials, 1992, Vol. 4, pp. 291-293. Reverse vesicles are a dispersion of lamellar liquid crystal, which swells a considerable amount of oil, i.e. the vesicles consist of reverse bilayer structures. The reverse bilayers are normally composed of a mixture of hydrophilic and lipophilic amphiph

REFERENCES:
patent: 4610868 (1986-09-01), Fountain et al.
patent: 5151272 (1992-09-01), Engstrom et al.
patent: 5234767 (1993-08-01), Wallach et al.
1. Foley et al., "Permeability of Liposomes Composed of Binary Mixtures of Monogalactosyldiaclglycerol and Digalactosyldiacglycerol", Chemical Abstracts, 108, 200519 (1988).

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