Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Liposomes
Patent
1997-05-28
1998-11-03
Lovering, Richard D.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Liposomes
424 121, 424 7803, 514887, A61K 9127
Patent
active
058304991
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a 371 of PCT/NL95/00325, filed Sep. 27, 1995, based on EPO 94 202783.0, filed Sep. 27, 1994.
FIELD OF THE INVENTION
The present invention relates to aqueous compositions, containing a pharmaceutically active principle and a vector system consisting of a mixture of non-ionic surfactants in the form of vesicles having a particle size between 10 and 1000 nm, for application to the skin.
BACKGROUND OF THE INVENTION
Aqueous compositions containing one or more non-ionic surfactants in the form of vesicles have been known for a long time (see e.g. FR-2315991, published in 1977). From the many scientific articles and patent publications, which were published since, it will be readily appreciated by a person of ordinary skill in the art that lipids, and in particular phospholipids and/or cholesterol, and stabilisers, such as sodium lauryl sulphate, have to be added to such aqueous compositions containing non-ionic surfactant(s) in order to prevent coalescence, aggregation, sedimentation and phase transitions, e.g. to a micellar phase.
However, phospholipids and cholesterol appeared to have some disadvantages when incorporated in compositions, which are intended to be marketed and, thus, have to meet certain standards. It is known that phospholipids are not stable on storage at ambient conditions. Special measures are required to protect said compounds against degradation by light and/or oxygen. Another disadvantage of phospholipids is that--as naturally occurring products--they are mixtures of ester compounds. The composition of the phospholipids may, thus, vary from batch to batch and from source to source. It is also known that cholesterol can be easily oxidised in the presence of light. Autooxidation may also occur. Although the compound is a naturally occurring compound, also in human beings, many efforts are directed to a limitation of the uptake of externally administered cholesterol.
Therefore, there is a need to prevent the use of phospholipids and cholesterol in aqueous compositions, comprising one or more non-ionic surfactants in the form of vesicles and further containing a drug, for application to the skin.
SUMMARY OF THE INVENTION
The invention relates to a phospholipid- and cholesterol-free aqueous composition for topical application to the skin comprising a pharmaceutically active principle and a vector system for the controlled and in-depth transport and release of said active principle through skin layers, said vector system consisting of at least one first, non-ionic surfactant, forming vesicles upon dispersion in water and a lamellar phase upon concentrating said vesicles, and at least one second, non-ionic, hydrophilic surfactant, the ratio of said at least one first, non-ionic surfactant and said at least one second, non-ionic surfactant being such that the vector system consists of flexible vesicles. Upon lowering the water concentration of the composition a lamellar phase is formed close to a cubic, hexagonal or viscous isotropic phase boundary.
The vesicles of the present invention have a particle size of from 10 to 1000 nm.
DETAILED DESCRIPTION OF THE INVENTION
It has been found that aqueous dispersions of vesicles can be made from a mixture of at least two non-ionic surfactants without using phospholipids and/or cholesterol and derivatives thereof, provided that at least one of the non-ionic surfactants can intrinsically form vesicles when dispersed in water and a lamellar phase upon concentrating said dispersion of vesicles at room temperature. The second surfactant is a hydrophilic surfactant and is not able to intrinsically form vesicles when dispersed in water. The HLB-value for the second surfactant is at least 12. In the final composition, comprising a medicament and the said mixture of non-ionic surfactants in water, vesicles are also present and upon lowering the water concentration of the composition a lamellar phase is formed which is close to a cubic, hexagonal or viscous isotropic phase boundary, mainly de
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patent: 5091111 (1992-02-01), Neumiller
Lovering Richard D.
Rijksuniversiteit Leiden
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