Hydrate of 5-[4-[2-(N-methyl-N-(2-pyridil)amino)ethoxy]benzyl]thiazolidine-2,4-dione maleic acid salt

A compound which is a hydrate of 5-[4-[2-(N-methyl-N-(2-pyridyl)amino)ethoxy]benzyl]-thiazolidine-2,4-dione, maleic acid salt, wherein said compound contains water in the range of from 0.2 to 1.1% w/w and said compound provides at least one of:

• (i) an infra red spectrum containing peaks at 764 and 579 cm−1;
• and
• (ii) an X-ray powder diffraction pattern substantially in accordance with FIG. II.