Sesquihydrate of naphthyridine derivative, and process for the preparation thereof

摘要

Novel 1-ethyl-6-fluoro-1,4-dihyono-4-oxo -7-(1-piperazinyl)-1,8-naphthyridine-3-carboxylic acid.sesquihydrate (ATT-2266.sesquihydrate). The aforesaid compound can be prepared by heating 1-ethyl-6-fluoro-1,4-dihydro-4-oxo -7-(1-piperazinyl)-1,8-naphthyridine-3-carboxylic acid at a temperature above about 60 DEG C. in the presence of water in an amount sufficient to form the sesquihydrate. This sesquihydrate is much more stable than the anhydrate and the trihydrate and is superior to the anhydrate in the rate of dissolution and transference into the body through the intestines. Thus, it is especially useful as a pharmaceutical compound.