Crystal Structure of Apraclonidine Hydrochloride

Apraclonidine is used for the treatment of postsurgical elevated intraocular pressure. The crystal structure of its hydrochloride, C9H10Cl2N4·HCl, was determined by X-ray analysis. The crystal belongs to space group P21/n with the cell dimensions a=9.665(10), b=11.8624(14), c=10.5675(11) Å, and β=92.199(9)°. The final R (all reflections) value is 0.053. Apraclonidine has a more twisted structure than its related drug of clonidine. The nitrogen atom bridging the two rings is protonated