Drug – bio-affecting and body treating compositions – Radionuclide or intended radionuclide containing; adjuvant... – In aerosol – fine spray – effervescent – pressurized fluid,...
Reexamination Certificate
2000-06-09
2003-10-07
Shukla, Ram R. (Department: 1635)
Drug, bio-affecting and body treating compositions
Radionuclide or intended radionuclide containing; adjuvant...
In aerosol, fine spray, effervescent, pressurized fluid,...
C424S009322, C424S009350, C424S400000, C424S491000, C424S497000
Reexamination Certificate
active
06630121
ABSTRACT:
BACKGROUND OF THE INVENTION
With advances in gene therapy and recombinant DNA technology, protein pharmaceuticals are an important class of therapeutic drugs. For example, pulmonary delivery of therapeutic peptides and proteins has received significant attention in recent years, for the treatment of respiratory illness and as an attractive alternative to injection for the systemic delivery of macromolecules. However, the commercial production of protein pharmaceuticals is severely limited by chemical and physical degradation of the proteins which can lead to biological inactivation (Manning, M. C. et al. (1989), “Stability of Protein Pharmaceuticals,” Pharm. Res. 6:903-918; Lai, M. C. and Topp, E. M. (1999), “Solid-State Chemical Stability of Proteins and Peptides,” J. Pharm. Sci. 88:489-500). Many of these degradation processes use water for hydrolysis and/or other degradation pathways. Therefore, many protein pharmaceuticals are prepared in the solid state as dry powders to prolong the useable shelf life of the product and the storage stability of the product. Protein unfolding in the dried solid can lead to irreversible denaturation upon immediate rehydration and significant reduction of long term storage stability.
Supercritical fluids are substances at a temperature and pressure above a critical temperature and pressure where the substance has a density, compressibility and viscosity intermediate between a gas and a liquid. Near-critical fluids are similar to supercritical fluids and are defined as fluids within 10% of the critical temperature and the critical pressure. For example, since the critical temperature of CO
2
is 31.6° C. (304.6K) and the critical pressure is 1073 psi, CO
2
above 2° C. (275K) and 966 psi is near-critical. Supercritical fluids have been researched for their use in the production of fine powders of pharmaceuticals, however these technologies (supercritical fluid nucleation (Larson, K. A. and King, M. L. (1986), “Evaluation of Supercritical Fluid Extraction in the Pharmaceutical Industry,” Biotechnol. Prog. 2:73-82), rapid expansion of a supercritical solution (Tom, J. W. and Debenedetti, P. G. (1991), “Precipitation of Bioerodible Microspheres and Microparticles by Rapid Expansion of Supercritical Solutions,” Biotechnol. Prog. 7:403-41 1) and gas antisolvent techniques (Randolph, T. W. et al. (1993), “Sub-micrometer-sized biodegradable particles of poly(L-lactic acid) via the gas antisolvent spray precipitation process,” Biotechnol. Prog. 9:429; Meyer, J. D. et al. (1998), “Preparation and in vitro characterization of gentamycin-impregnated biodegradable beads suitable for treatment of osteomyelitis,” J. Pharm. Sci. 87:1149; Winters, M. A. et al. (1996), “Precipitation of proteins in supercritical carbon dioxide,” J. Pharm. Sci. 85:586; Palakodaty, S. et al. (1998), “Supercritical fluid processing of materials from aqueous solutions: the application of SEDS to lactose as a model substance,” Pharm. Res. 15:1835) require that the pharmaceutical be soluble directly in the supercritical fluid or be precipitated by the supercritical fluid from nonaqueous solvents such as dimethylsulfoxide. The nebulizer system disclosed in U.S. Pat. No. 5,639,441 (Sievers, R. E. and Karst, U., issued Jun. 17, 1997) and divisional application 08/847,310 permits the use of mixtures of supercritical fluids with immiscible liquids such as water to process substances that are not soluble in the supercritical fluid to form aerosols of vapors. Therefore, using the methods and devices disclosed in U.S. Pat. No. 5,639,441 particles of water soluble proteins, excipients, stabilizers, bulking agents and/or surfactants may be formed rather than just particles of those compounds that are soluble in supercritical fluids and/or organic solvents. U.S. Pat. No. 5,639,441 is hereby incorporated by reference, to the extent not inconsistent with the disclosure herein. Unlike the other precipitation methods, e.g., the SEDS process and GAS processes referred to above, no organic solvents are required in the new process; only the drug, water and the supercritical or near-critical fluid (for example, carbon dioxide) are needed.
Even though particles of water soluble proteins and other aqueous formulations can be prepared, no method to form suitable dry powders of these proteins and/or formulations existed until now. Existing technologies to produce dry protein powders, such as spray-drying, freeze-drying, or ultrasonic nebulization, suffer from a variety of problems. In general, dry protein powders are often irrevocably inactivated when produced by prior art methods because the processing steps involved in these methods, temperature required to dry the proteins using these methods and dehydration processes of these methods damage the delicate structure of the protein. Also, for use in direct inhalation applications, powders must be small enough to allow for effective pulmonary delivery. Drug delivery via a pulmonary route is preferred over other delivery routes such as injections for reasons such as decreased pain and delivery of the drug to the desired location more quickly. If the particles produced by the drying process are larger than desired, they must be jet-milled or mechanically ground. This creates an additional physical stress on the molecules and may impart a further loss of protein activity. Dry powders produced in the correct size region could be used directly in dry powder inhalers for pulmonary delivery.
Spray-drying is a currently-available method to produce dry protein powders. In the spray-drying technique, a jet nebulizer is used to form a plume of droplets. In one type of nebulizer, a liquid sample is sucked through a small diameter tube by a high-pressure stream of gas. The gas breaks up the liquid into fine droplets. The gas can also flow across the small diameter tube at right angles and form droplets in a similar manner. Ultrasonic nebulizers use ultrasonic vibrations coupled to the sample solution that cause the solution to break up into small droplets. One disadvantage of the method of spray-drying is the plume of molecules exiting the jet nebulizer is not very dense. This results in a process that is slow in producing a desired amount of protein. Freeze-drying is another currently used method to produce dry protein powders wherein aqueous solutions of drugs are frozen and placed under a vacuum to sublime the water. One disadvantage of the method of freeze-drying is the drying process is very slow. Also, the particles produced are relatively large, requiring additional processing steps to produce pharmaceutically desirable sizes.
U.S. Pat. No. 6,063,138 (Hanna, et al., issued May 16, 2000) and related EP 0767702 describes methods of forming particles of a substance by co-introducing a supercritical fluid; a solution or suspension of the substance in a first vehicle; and a second vehicle which is substantially miscible with the first vehicle and substantially soluble in the supercritical fluid into a particle formation vessel which is maintained at supercritical pressure and temperature.
PCT published application PCT/US99/19306 (WO 010541) (Edwards et al.) describes methods of forming particles by combining a bioactive agent, a phospholipid and an organic solvent or organic-aqueous co-solvent to form a mixture which is then spray-dried.
U.S. Pat. No. 5,695,741 (Schutt et al., issued Dec. 9, 1997) and related U.S. Pat. No. 5,639,443 (Schutt et al., issued Jun. 17, 1997) and U.S. Pat. No. 5,720,938 (Schutt et al., issued Feb. 24, 1998) describe “microbubbles” useful for magnetic resonance imaging and ultrasound imaging. The “microbubbles” are prepared by spray-drying a liquid formulation to produce microspheres having voids and then permeating the microspheres with a fluorocarbon gas osmotic agent.
U.S. Pat. No. 5,928,469 (Franks et al., issued Jul. 27, 1999) describes mixing materials with a carrier substance that is water-soluble or water-swellable and spray drying the resultant mixture to form particles containing both the material and the carrier substance in wh
Carpenter John F.
Sellers Scott P.
Sievers Robert E.
Greenlee Winner & Sullivan, P.C.
Shukla Ram R.
The Regents of the University of Colorado
Zara Jane
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