Pharmaceutical composition containing a stable modification of torasemide

Abstract

The present invention provides a process for the preparation of cystalline torasemide in the pure modification I (monoclinic, space group P21/c, melting point 162 DEG C.) from torasemide of modification II (monoclinic, space group P2/n, melting point 169 DEG C.), wherein a suspension of torasemide of modification II is stirred in water with the addition of a catalytic amount of modification I until the rearrangement is complete. The present invention also provides pharmaceutical compositions containing torasemide of modification I.

What is claimed is: 
     
       1. A diuretic pharmaceutical composition comprising an effective amount of rapidly dissolving .Iadd.stable .Iaddend.crystalline torasemide of pure modification I (monoclinic, space group P2 1  /c, melting point .Badd..[.169° C..]..Baddend. .Iadd.of about 159° C. to about 161.5° C., in prism form.Iaddend.) substantially free of crystalline torasemide of modification II (monoclinic, space group P2/n, melting point .Badd..[.162° C..]..Baddend. .Iadd.of about 157.5° C. to about 160° C., in leaflet form.Iaddend.) and a pharmacologically acceptable carrier, said torasemide of modification I .Iadd.being storage stable in tablet form and .Iaddend.having solubility characteristics such that at least 60% is dissolved in water after 15 minutes, and at least 80% is dissolved in water after 30 minutes. 
     
     
       2. The composition of claim 1 comprising, by weight, approximately: 100 parts of the torasemide of modification I and, as the carrier,   20 parts lactose monohydrate,   77 parts maize starch,   2parts silicon dioxide and,   1 part magnesium stearate.   
     
     
       3. The composition of claim 1 comprising, by weight, approximately: 25parts of the torasemide of modification I and, as the carrier,   605 parts lactose monohydrate,   160 parts maize starch,   6 parts silicon dioxide and   4 parts magnesium stearate. .Iadd.   
     
     
       4.  A method of producing a diuretic effect in a patient, said method comprising orally administering to the patient at least one storage-stable table consisting essentially of torasemide of pure modification I (monoclinic, space group P2 1  /c, melting point of about 159° to about 161.5° C., in prism form) and being substantially free of crystalline torasemide of modification II (monoclinic, space group P2/n, melting point of about 157.5° C. to about 160° C., in leaflet form). .Iaddend.