Physico-chemical properties and stability of the new hypoxia-selective agent 7-chloro-3-[[(N,N-dimethylamino)propyl]amino]-2-quinoxalinecarbonitrile 1,4-di-N-oxide hydrochloride

7-Chloro-3-[[(N,N-dimethylamino)propyl]amino]- 2-quinoxalinecarbonitrile I ,4-di-N-oxide hydrochloride (Q-85 HCI), a new hypoxia-selective agent, was studied to clarify its physico-chemical properties. Melting point, spectra (UV, IR, NMR, MS), thermal behaviour, solubility, pK a , partition coefficient and chromatographic characteristics (TLC, HPLC) have been determined. The stability of Q-85 HCI was studied under various conditions by HPLC. Q-85 HCI in solid state was very stable to heat and fairly stable to light. Some degradation products of Q-85 HCI were identified in basic solution.