Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Liposomes
Reexamination Certificate
1999-12-07
2001-05-29
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Liposomes
C424S426000, C264S004100
Reexamination Certificate
active
06238694
ABSTRACT:
The present application is the national stage filing of and claims priority to International Application No. PCT/EP98/03110, filed May 27, 1998 and Italian Application Serial No. MI97A001385.
PRIOR ART
Solid lipidic microspheres having a diameter lower than one micrometer obtained for example adding a mixture formed by water, a surfactant and a co-surfactant to a melt lipidic substance and dispersing the obtained microemulsion in cold water are known.
Microspheres of this kind and the relating preparation process are described for example in the European Patent 0526666B1.
Said microspheres are important carriers of drugs, however in the case of parenteral administration they may show a significative limitation.
In fact the presence of the lymphoreticular system causes a fast clearance of the lipidic particles due to the effect of the phagocytosis by the macrophages, from which a limitation to the parenteral use of said microspheres as transport systems of drugs derives.
SUMMARY
Now we have found a pharmaceutical composition in form of lipidic solid microparticles shape which allow to overcome the drawbacks of the prior art. Said microparticles have an average diameter lower than one micrometer and a polydispersion index ranging from 0.10 to 0.50 and they are characterized in that they contain a drug and one or more substances suitable to sterically stabilize the microparticies.
The process for the preparation of said microparticles includes:
a) heating a lipidic substance at a temperature at least equal to its melting point;
b) heating a mixture comprising water, a surfactant and a co-surfactant at a temperature at least equal to the melting point of the lipidic substance of the step a);
c) putting the lipidic substance of the step a) in contact with the mixture of the step b) obtaining a micro-emulsion;
d) dispersing the micro-emulsion obtained in the step c) in cold water;
e) washing the dispersion of the step d) with distilled water by diafiltration, and it is characterized in that at the end of the step c) a drug and one or more substances suitable to sterically stabilize said microparticles are added.
The composition according to the present invention turns out to be suitable for the parenteral administration.
REFERENCES:
patent: 5744155 (1998-04-01), Friedman et al.
patent: 5985354 (1999-11-01), Mathiowitz et al.
patent: 2091152 A1 (1994-09-01), None
patent: WO 526666 A1 (1993-02-01), None
Baron Liliana Dinola
Hedman & Costigan ,P.C.
Page Thurman K.
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