Tiamenidine (also known as HOE 440) is a diazacycloalkene derivative patented by Farbwerke Hoechst A.-G. as 2 alpha-sympathomimetic antihypertensive agents. In preclinical models, tiamenidine induces hypotension and bradycardia in renal hypertensive cats and rats and in normal rats and dogs. Furthermore, Tiamenidine inhibits the liberation of norepinephrine from nerves leading to the heart and suppress sympathetic circulatory reflexes in dogs. In clinical trials, Tiamenidine exerts favor influences on systolic and diastolic blood pressure, and reduces plasma noradrenaline and adrenaline levels and suppresses plasma renin activity. Unfortunately, during the withdrawal of Tiamenidine, there is a rebound of blood pressure and plasma noradrenaline and adrenaline, overshooting baseline levels.