|Title:||Stabilized preparation for use in metered dose inhalers|
|Abstract:||Stabilized dispersions are provided for the delivery of a bioactive agent to the respiratory tract of a patient. The dispersions preferably comprise a plurality of perforated microstructures dispersed in a suspension medium that typically comprises a hydrofluoroalkane propellant. As density variations between the suspended particles and suspension medium are minimized and attractive forces between microstructures are attenuated, the disclosed dispersions are particularly resistant to degradation, such as, by settling or flocculation. In particularly preferred embodiments, the stabilized dispersions may be administered to the lung of a patient using a metered dose inhaler.|
|Inventor(s):||Weers; Jeffry G. (San Diego, CA), Schutt; Ernest G. (San Diego, CA), Dellamary; Luis A. (San Marcos, CA), Tarara; Thomas E. (San Diego, CA), Kabalnov; Alexey (Corvallis, OR)|
|Assignee:||Nektar Therapeutics (San Carlos, CA)|
|Filing Date:||May 21, 2001|
|Claims:||1. A system for the pulmonary administration of a bioactive agent comprising: a fluid reservoir; a metering valve operably associated with said fluid reservoir; and a stabilized dispersion in said fluid reservoir wherein said stabilized dispersion comprises a suspension medium having dispersed therein a plurality of perforated microstructures comprising a mean aerodynamic diameter of less than 5 .mu.m and comprising at least one bioactive agent wherein said suspension medium comprises at least one propellant wherein more than 30% of the average particle volume of the perforated microstructures is permeated by said suspension medium. |
2. The system of claim, claim 1 wherein said fluid reservoir comprises a pressurized aerosol container and wherein said metering valve is adapted to dispense a pharmaceutically acceptable amount of said bioactive agent in the form of an aerosol upon activation.
3. The system of claim 1, wherein said propellant comprises a compound selected from the group consisting of 1,1,1,2-tetrafluoroethane, 1,1,1,2,3,3,3-heptafluoro-n-propane, perfluoroethane, monochlorodifluoromethane, 1,1-difluoroethane and combination thereof.
4. The system of claim 1 wherein said propellant comprises a hydrofluoroalkane propellant.
5. The system of claim 4 wherein said hydrofluoroalkane propellant comprises 1,1,1,2-tetrafluoroethane.
6. The system of claim 4 wherein said hydrofluoroalkane propellant comprises 1,1,1,2,3,3,3-heptafluoro-n-propane.
7. The system of claim 1 wherein said perforated microstructures comprise a surfactant.
8. The system of claim 7 wherein said surfactant is selected from the group consisting of phospholipids, nonionic detergents, nonionic block copolymers, ionic surfactants, biocompatible fluorinated surfactants and combinations thereof.
9. The system of claim 7 wherein said surfactant comprises a lipid.
10. The system of claim 9 wherein said lipid has a gel to liquid crystal phase transition greater than about 40.degree. C.
11. The system of claim 8 wherein said lipid is a phospholipid.
12. The system of claim 10 wherein said phospholipid is selected from the group consisting of dilauroylphosphatidylcholine, dioleylphosphatidylcholine, dipalmitoylphosphatidylcholine, disteroylphosphatidylcholine, behenoylphosphatidyl-choline, arachidoylphosphatidylcholine and combinations thereof.
13. The system of claim 7 wherein said perforated microstructures comprise greater than about 20% w/w surfactant.
14. The system of claim 1 wherein said suspension medium and said perforated microstructures have a refractive index differential of less than about 0.4.
15. The system of claim 1 wherein said perforated microstructures comprise hollow porous microspheres.
16. The system of claim 1 wherein the mean geometric diameter of the perforated microstructures is between 1 and 30 .mu.m.
17. The system of claim 1 wherein the mean geometric diameter of the perforated microstructures is less than 5 .mu.m.
18. The system of claim 1 wherein said bioactive agent has a fine particle fraction following aerosolization of greater than 30%.
19. The system of claim 1 wherein the density of the suspended particles permeated with the suspension medium substantially matches that of the suspension medium.
20. The system of claim 1 wherein said bioactive agent is selected from the group consisting of antiallergics, bronchodilators, pulmonary lung surfactnats, analgesics, antibiotics, leukotriene inhibitors or antagonists, antihistamines, antiinflammatories, antineoplastics, antcholinergics, anesthetics, anti-tuberculars, imaging agents, cardiovascular agents, enzymes, steroids, genetic material, viral vectors, antisense agents, proteins, peptides and combinations thereof.
21. The system of claim 20 wherein the active agent comprises an anti-inflammatory agent and a bronchodilator agent.
22. The system of claim 21 wherein the anti-inflammatory agent comprises a steroid.
23. The system of claim 21 wherein the anti-inflammatory agent is selected from the group consisting of fluticasone, beclomethasone, flunisolide, budesonide, tripedane, cortisone, prednisone, prednisilone, dexamethasone, betamethasone, and triamcinolone.
24. The system of claim 23 wherein the bronchodilator is selected from the group consisting of ephedrine, adrenaline, fenoterol, formoterol, isoprenaline, metaproterenol, salbutamol, albuterol, salmeterol, and terbutaline.
25. The system of claim 23 wherein the bronhodilator and anti-inflammotory agents are provided in combination in a single species of perforated microstructure.
26. The system of claim 23 wherein the bronhodilator and anti-inflammotory agents are provided individually in separate species of perforated microstructures.
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