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1. (CA2415081) DRUG DELIVERY SYSTEM FOR POORLY WATER SOLUBLE DRUGS
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CLAIMS
1. A drug delivery system comprising a chitosanxanthane hydrogel, said hydrogel including in its matrix a poorly water soluble drug which upon swelling of said hydrogel in an aqueous medium becomes at least partially solubilized and releasable therefrom.
2. A drug delivery system as defined in claim 1, wherein said hydrogel comprises: (a) about 18-35% (w/w) of chitosan; (b) about 32-55% (w/w) of xanthane; and (c) about 10-55% (w/w) of a poorly water soluble drug.
3. A drug delivery system as defined in claim 1, wherein said chitosane possesses a degree of acetylation ranging from about 10% to about 30%.
4. A drug delivery system as defined in claim 1, wherein the amount of said poorly water soluble drug included in said hydrogel is varied between about 10 to 50% (w/w).
5. A drug delivery system as defined in claim 1, wherein said poorly water soluble drug is selected from the group consisting of fenofibrate, ursodeoxycholic acid, nifedipine and indomethacin.
6. A drug delivery system as defined in claim 1, comprising about 20-40% chitosan and about 80-60% xanthane.
7. A method for preparing said drug delivery system of claim 1, comprising the following steps: a) dissolving said poorly water soluble drug in an appropriate solvent so as to form a first solution; b) adding said first solution to a xanthane solution, so as to form a dispersion; c) adding said dispersion to a chitosan solution, and d) recuperating the hydrogel thus formed.
8. A method as defined in claim 7, further comprising the step of freeze-drying said recuperated hydrogel.
9. A method for modifying the solubilization rate of a poorly water soluble drug which comprises the step of including said poorly water soluble drug in a hydrogel composed of a chitosan-xanthane microstructure, said microstructure governing said solubilization rate.
10. A method as defined in claim 9, wherein said chitosane-xanthane microstructure and drug retention strength can be altered by selecting a chitosane of proper molecular weight or of proper degree of acetylation or both.
11. A method as defined in claim 10, wherein said chitosan-xanthane microstructure provides a high retention strength and thus a slow release rate of said poorly water soluble drug, said chitosane-xanthane microstructure being formed with chitosan of a molecular weight ranging from about 900 000 Da to about 1 200 000 Da and wherein said chitosan possesses a degree of acetylation ranging from about 10% to about 30%.
12. A method as defined in claim 11, wherein said chitosan has a molecular weight of about 1 100 000 Da.
13. A method as defined in claim 10, wherein said chitosan-xanthane microstructure provides a low retention strength, and thus a rapid release rate of said poorly water soluble drug, said chitosan-xanthane microstructure being formed with chitosan of a molecular weight ranging from about 500 000 Da to about 900 000 Da and wherein said chitosan possesses a degree of acetylation ranging from about 10% to about 30%.
14. A method as defined in claim 13, wherein said chitosan has a molecular weight of about 800 000 Da.
15. A method as defined in claim 13, wherein said chitosan has a molecular weight of about 540 000 Da.
16. A method as defined in claim 7, wherein said appropriate solvent is ethanol.
17. A method as defined in claim 7, wherein said xanthan solution is 0.65% w/v.