Hot melt method for preparing diphenhydramine tannate
AssigneeJame Fine Chemicals, Inc.
InventorsSham N. Redkar, Raja G. Achari, James R. Schleck, Vilas M. Chopdekar
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Abstract
The invention pertains to a method for preparing diphenhydramine tannate by reacting diphenhydramine free base at a temperature of about 75 to about 150° C. with tannic acid neat or as an aqueous slurry containing up to about 20 wt. % water. The diphenhydramine free base may be obtained by reacting a commercially available diphenhydramine salt such as diphenhydramine maleate with a base such as aqueous sodium hydroxide. The resultant diphenhydramine tannate has extended release properties and is useful in pharmaceutical compositions as an antihistamine for human beings.
Claims11
A hot melt method for preparing diphenhydramine tannate which comprises reacting diphenhydramine free base with tannic acid in the presence of 0 to about 20 wt. % water at a temperature of about 80 to about 150° C. and thereafter recovering the resultant diphenhydramine tannate.
The method of claim 8 wherein the powder has a particle size in the range of about 50 to about 200 mesh.
The method of claim 10 wherein the diphenhydramine salt consists of diphenhydramine maleate.
Dependencies are inferred from the claim text.