Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Matrices
Patent
1998-02-06
1999-11-16
Webman, Edward J.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Matrices
424486, 424487, 424488, A61K 910, A61K 4732, A61K 4738
Patent
active
059853263
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the field of solid dispersions of poorly water soluble drugs, to processes for their preparation and their use in pharmaceutical compositions. More particularly the present invention relates to solid dispersions in the form of co-precipitates of poorly water soluble drugs and their compositions with a pharmaceutically acceptable carrier or excipient therefor. Specifically, the invention relates to co-precipitates of (a) a potent and selective inhibitor of cyclic guanosine 3',5'-monophosphate specific phosphodiesterase (cGMP specific PDE) and (b) a potent and selective gastrin and CCK B antagonist, processes for the preparation of such solid dispersions, pharmaceutical compositions containing the same and their use thereof in therapy.
Co-precipitation is a recognised technique for increasing the dissolution of poorly water soluble drugs, such as griseofulvin, ketoprofen, sulphathiazide, spirinolactone, tolbutamide and nifedipine, so as to consequently improve bioavailability thereof. Techniques such as solvent deposition, lyophilization, solvate formation and solid dispersion (of which co-precipitation is an example as described above) have therefore been developed to try to overcome the problem of poor water solubility and resultant low bioavailability.
Solid dispersions in the pharmaceutical field are dispersions of one or more active ingredients, generally poorly water soluble drugs, in an inert carrier or matrix at solid state, which are prepared by either melting the two (fusion), or dissolving them in a solvent, or a combination of approaches, followed by removal of the solvent.
Manufacture of pharmaceutical dispersions by the above referred to melting or fusion technique, involves fusion of the two components where the drug and the carrier are allowed to melt at temperatures at or above the melting point of both the drug and carrier. In the fusion process, the drug and carrier are first blended and both melted in a suitable mixer. The molten mixture is then cooled rapidly to provide a congealed mass which is subsequently milled to produce a powder. The fusion process is technically simple provided that the drug and carrier are miscible in the molten state but this is not always the case and furthermore, the process is limited in that it tends to lead to drug decomposition due to the high temperatures required to melt the two components.
The solvent-based process uses organic solvents to dissolve and intimately disperse the drug and carrier molecules. Identification of a common solvent for both drug and carrier can be problematic, and complete solvent removal from the product can be a lengthy process. In addition, large volumes of solvents are generally required which can give rise to toxicological problems. The drug and carrier are typically dissolved in a solvent such as methylene chloride, acetone, ethanol and mixtures thereof and the solvent is later removed by precipitation techniques, evaporation or the like, while the drug/carrier solid dispersion is collected as a powdered mass.
In the case where there is difficulty with thermal instability and immiscibility between the drug and the carrier, the hybrid fusion-solvent method can be employed. The drug is first dissolved in a small quantity of organic solvent and added to the molten carrier. The solvent is then evaporated to generate a product that is subsequently milled to produce a powder. The pharmacokinetics, dissolution rates and processes for formulation of many different solid pharmaceutical dispersions is discussed at length in an article by Ford J., in Pharm. Acta. Helv. 61, 3; 69-88 (1986).
Co-precipitation techniques employ the use of an organic solvent or solvents to dissolve and intimately disperse the drug and carrier molecules as hereinbefore described. Separation of the drug and carrier from the solvent on precipitation can rely on the solubility properties of either the drug or carrier. For example, Simonelli et al, Journal of Pharmaceutical Sciences, Vol. 58, No. 5, May 1969, describes a co-preci
REFERENCES:
patent: 5194263 (1993-03-01), Chamberlain et al.
patent: 5665331 (1997-09-01), Bagchi et al.
ICOS Corporation
Webman Edward J.
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